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Charging AGM Battery

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Forum Name: General Discussion
Forum Discription: General Mobile Electronics Questions and Answers
Printed Date: August 18, 2022 at 5:13 AM

Topic: Charging AGM Battery

Posted By: rfhvhtoo
Subject: Charging AGM Battery
Date Posted: December 04, 2010 at 6:55 AM

Hey I'm wondering out of all the high and low end Battery chargers, what are some or a good priced chargers I can purchase for my 100ah Shuriken battery? I've been told AGM's need specific chargers and cheap ones from walmart won't be able to do the job as good and other cheap ones my damage it. Its for my car stereo and its starting to sit pretty low in voltage.. also what are the best ways of charging it?



I can't hear you!


Posted By: oldspark
Date Posted: December 04, 2010 at 8:03 AM
Never exceed 14.4V @ room temp else whatever the manufacturer recommends. Many cheaper chargers do not have limit the voltage...

Do not exceed its max charge current, though for a 100AH capacity, that is unlikely (I'd expect well over 20A...??).

Some manufacturers seem to suggest a minimum charge current (else battery life is compromised).
Some suggest or require higher than the "normal" commonly accepted "max" charge voltage of 2.4V/cell (14.4V) - the accepted "onset of gassing" voltage for lead-acid batteries.
But again, refer to the manufacturer's recommendations - after all, it is their warranty conditions that you have to meet.

And as with all lead-acid batteries, if charged above their float voltage (2.3V/cell = 13.8V), once they are fully charged, the charge voltage should be reduced to 13.8V (eg, from 14.4V).
But that is from a "max life" POV. Many if not most car alternators stay at 14.2 or 14.4V etc. (But they don't measure battery current nor temperature and hence do not know when the battery is fully charged - unlike the Projecta batter isolator that some how does it remotely though a simple +12V & ground connection! Amazing stuff eh? But I shouldn't highlight their alleged "priority charging"... posted_image posted_image
Battery chargers however can determine when the battery is (apparently) full, hence their various charge "modes".

"Smart" AGM chargers are the same as wet cell chargers except they lock out boost charging (?? - or whatever... I forget - ie, voltages above 2.4V/cell = 14.4V).
And they may impose a current limit suitable for that AH.
But otherwise they are the same "constant voltage" charger (with different voltages used for each stage; in ye olde days, "constant current" charging was recommended for AGMs).

But the key issues:
- do not overcharge; they do not have fluid to absorb the heat etc. This mainly refers to voltage limits (eg, 14.4V max longterm) but also over-current (heating).
- recharge ASAP after discharge - especially if a full or deep discharge. Unlike wet cells, they cannot be de-sulfated nor given the same rejuvenating resuscitation.

And please do not short circuit their terminals!

Posted By: rfhvhtoo
Date Posted: December 05, 2010 at 1:45 AM
Thank you! for the detailed response! would you be able to direct to a good battery charger? On amazon or another online store? I Just need an idea of the specs and things that I'm looking for. The Manufacturer has a charger but its COST more than the battery! and they give no details about it on their website. But I will email them and ask to amke sure like you said.

Also "discharge" means whenever the battery has gone below 10.5 volts right?

because you say "recharge ASAP after discharge"

Thanks again!

I can't hear you!

Posted By: oldspark
Date Posted: December 05, 2010 at 4:19 AM
{Updated - corrected Projecta to Pro-User. I must have Projecta on my litigious mind!}

Discharge means any discharge.
But as I said - "especially if a full or deep discharge".
It's really the same with any lead-acid battery - it should be recharged ASAP.
As soon as they discharge, sulphates form on the plates. That impeded efficiency.
The more discharged aka flatter they are, the faster the sulphate forms.
Where is becomes a problem is arbitrary. Technically as soon a you stop charging and the surface charge has disappeared, it starts discharging through its internal resistance. Hence sulfation starts - but at an insignificant rate.
And self-discharging generally isn't a problem for 3 months wet cells or 12 months for AGMs. (I recently witnessed a wet battery that had been untouched for 2 years. It worked fine after (I assume!) a recharge. But that's impossible - it even stretches AGM capabilities....!)
But as per earlier - wet cells can be "reconditioned". AGMs can't - at least not in the same way...

Since you mention 10.5V, I assume you are talking about a specific discharge rate - ie, 10.5V open circuit means a very damaged battery; and 10.5V at 1A or 10A discharge will soon be as damaged...

I normally talk open-circuit voltages as that is the only universally applicable measurement - hence ~11.3V is fully discharged; 12.7V is fully charge - above that is surface charge else charging voltage; charging above 14.4V is gassing...

And fully discharged is a damaged battery. Crankers should not be discharged more than 30% (~12.3-12.4V), and deep-cycles not less than 50% according to many - even if supposedly 70% and 90% dischargeable. But even 90% discharged is not as low as 11.3V.

To quote eg 10.5V as a level of discharge is applicable only to that discharge rate (for that battery).
My fully charged cranking battery reads 9.5V during cranking yet is is 100% charged.

FYI - I recently saw someone else recommend a favorite of mine from years ago, namely (also aliased as - last updated September 13, 2010. (Hmmm - maybe I should review?)

As to charger recommendations - I have none.
I have a 6V/12V 2A/8A Pro-User BCH8 that I got for $30 (Jaycar).
I use a multimeter to monitor its voltage...

If I need a hard-charge (ie, over 20A to de-sulphate plates or kick AGMs into submission), I connect them to my trusty 1965 ute (with its 1980s Hitachi/Mitsubishi >70A alternator).

However, recently Aldi had a charger that seemed too good to be true for $25 - a switchmode charger with 4 or 5 modes; "microcomputer cointrolled", and from memory, "up to 120AH" - though I think it was about 7A (or maybe 4A?)...
(the above from

Alas by the time I decided it was something I didn't need but wanted it anyhow (like, I mean, for $25 bucks man!), they were all sold....

As long as they have an AGM/VRLA setting so they do not exceed 14.4V.
And AFAIAConcerned, even 4 Amps is fine EXCEPT if you require faster charging OR if you need to blast off the cobwebs (for which my guru recommends 20A or more for car batteries - ie, too expensive!) OR the manufacturer states otherwise.

There was something about a well known AGM manufacturer claiming a MINIMUM recharge current of significant proportion (like 10A or 56A...?), but I'm not a fan of them... They allegedly suggested giving a free battery for one that had lasted 13 years (that's about 12 years 9 months longer than the ones I have dealt with). LOL! My 11 year old AGM is doing fine despite its unintended car use. (Not that I'm one to admire "the olde" Yuasa batteries.)

Posted By: oldspark
Date Posted: December 06, 2010 at 1:02 PM
rfhvhtoo - how do you intend using the AGM battery?
In storage, or a total loss system, or car (cranking) or audio?

Like I said - I use a $30 charger (normal price is ~$60-$70).
My flooded car batteries tend to last a minimum of 6 years despite abuse. (And I only recently upgraded to non-external non-electromechanical voltage regulators.)
I am now using a 10 year old 38AH AGM battery that I obtained when it was 5 years old. I had it in storage until this or last year. (I was reluctant to use it as a cranker, but when my brother said he had been using his for 3.5 years....)
I'd top it up every year or 2 with the 8A charger until it reached ~14.5V (and at times a bit higher... posted_image ) and it still seems fine. (An alternator-less night-drive home some time back indicated it still had its original 38AH reserve; I discharged it ~50% over 60 minutes.)

The only battery I had troubles with was a new ~55AH wet cell which was little used for ~24 months. It was topped up every 3-6 months.
Despite seeming fine when charging prior to use as my 2nd battery to run a 12V 5A fridge, the MW728 battery protector (low voltage cutout) was cycling at ~15-30 second intervals.
The battery was dipping to the MW728's 11.2V off-voltage, and then recovering to its 12.5V on-voltage. (A typical problem for voltage-switched isolators...)
But as suspected, it came good after a few minutes with the engine running - I figured it needed the >16A or >20A blast to kick the sulphate off the plates... (I had a 75A alternator rather than the standard 23A generator (LOL!).)

The point is, with some nous, you can do quite well without sophisticated stuff. For one ctek charger I can by 3 cranking batteries. And since I retired my last batteries after 8 years service...
(I'm not like other Aussies that buy $300-$500 dc-dc converters to charge their auxiliary batteries. I prefer the big-3 to the big-300 or $500! Besides, I'd rather boost alternator output and then chop it down if required (instead of chopping "up" with a dc-dc converter).

I happened to see the CTek charger (US7002) with max 7A charge rate as recommended for up to ~150AH, whilst the US3300 (maybe 3.3A max?) is for up to 75AH or 90AH. So maybe a 4A charger is enough....

I got some 4A chargers for $5 each at a sale. I merely replaced the blade fuse with a circuit breaker as they don't like real flatteries (my Pro-User handles them fine - presumably it has current limiting).

But bigger is good if not too expensive. (Battery chargers have become another vvankathon with their 2200, 2500, 2700, 3300, 4200mA etc. Unbelievable!)
Not that I could find the specs on the Shuriken - I'd refer to the equivalent Kinetik else the Battery-FAQ link....

Beware though - I was amazed at the misinformation - like one place saying the Shuriken SK-BT100 is a Gel-Cel; or the above ctek 3300 for "up to 75AH" or "up to 90AH"...

I also saw another site's Dual Battery Wiring sticky/tutorial.... IMO it matched the quality of their discussion generally (eg, batteries are "poor" because they perform worse in dB comps. That means they have a lower internal resistance and are better batteries! But yes, that means lower audio peak-dB).
But it used the old matched batteries.... (except for location and non-diagonal wiring).
At least they agreed battery life is compromised by paralleling... yay!

Sorry - I said I'd go to bed an hour ago. The sun is just rising and I'm still warm from yesterday.

Posted By: oldspark
Date Posted: December 08, 2010 at 12:06 AM
Update -

Reading as updated 7Dec2010, Darden recommends linking to as the primary source.

I also recommend downloading the file (as linked in the above).

Just unzip it to a directory of your choice and, once started from any of its hatemail pages (.htm), it should page fwd & back and link correctly.

[ EG - Under my D:\Technical\Batteries I created a "BatteryFAQ.20101207" directory and moved to it.
Extracting (from) should then place files under a \battery sub-directory.
Create a link/shortcut to "index.htm" and place it wherever you want. (In windoze, I usually right-click & Send to Desktop to create the shortcut and then move to wherever... ]

PS - I'm glad I left my review of BatteryFAQ till today! (Let's see where we disagree this time... LOL!)

PPS (after initial posting) - Reading "1. WHAT IS THE BOTTOM LINE AND TIPS?" (carfaq1) slowly and thoroughly should be MANDATORY.

Posted By: rfhvhtoo
Date Posted: December 08, 2010 at 9:33 PM
Sorry it took a while to reply my computer went down for a couple of days. But I dont have too much to disagree with you on this one lol You KNOW batteries. I just didnt realize how much maintenance you have to do on maintenance free batteries! Compared to what you're saying I've been neglecting my battery horribly for about a year now. I need to get it charging ASAP But its my Main battery so I can't leave it charging for days. And the charger you recommended is similar to the one that SHuriken actually has on their website

but i found this one as well

how does it look?

I can't hear you!

Posted By: oldspark
Date Posted: December 09, 2010 at 1:54 AM
Not that I waste time researching...
I was gonna say that cteks are expensive, but ~$110 is cheaper than I thought. I have only read good things about them. (I guess some Swedes are good at design & build. posted_image Go Grippen, but I still want a Viggen!)

And having looked into this $30 Schumacher SC-600A "high frequency" bullsh...   I reckon go for it.
Its owner's manual (here) clearly states AGM compatibility. Even a desulfating mode. I like it! posted_image

I thought I did well with my $30 8A "linear" (heavy transformer) non-auto charger. But a $30 uProcessor-controlled charger with "high frequency" either referring to its SMPS supply (at under 2.8lbs - it must be) or its desulfation mode. (Add-on kits for that feature alone sell for $50 to $100 here!)

The SC-600 seems good. For $30 vs $110, or even $65 vs $110, I'd want to know what justifies the >$doubling for a ctek (based on the published blurb).
The bad SC-600 reviews seem like warranty issues, or people not being as expert as you on batteries (ie, after charging, a battery was 13V, der... surface charge... d'oh. The O-manual mentions surface charge for the test mode in the other models.)

But please confirm with your own search & destroy.... (mine was quick - not that I spend,, waste time researching....)   

Remember that I'm happy with mine... I set it for 8A and then reduce to 2A when the voltage hits ~14.4V, or when I see it at 15.x Volts hours later...
Or I leave it on 2A for a reasonable safe limit - though it will still exceed 14.5V eventually. (I could use a pluggable lamp timer if it mattered...)
But I do have a DMM. Several actually - & I'm thinking of fitting an ~$8 eBay blue backlit LCD voltmeter permanently. Read: Tape to the handle or charger case and run its 2 wires to the alligator/battery clamps etc.
A voltmeter is essential, but every car person should have a DMM - often $10-$20 is enough & rarely more than ~$25 for most needs.     

Having now answered your question with no care and no responsibility, I can relax.
And maybe now ramble a bit....
(I'll leave Dual battery setups till later in case you have seen my "Ultimate Intelligence" Battery Isolator (Patent Pending - in about 20 years... geez I'm so impatient!).)

& BTW - I thought 8A was too little for a 100AH battery, but it is enough. It may even be "too much" (Darden recommends against Fast Charging - but that's a lifetime issue). But a car battery might take all the left over alternator output (eg, a 120A alternator that CAN put out (say) 90A @ 3kRPM and the rest of the vehicle is only using 60A - that's 30 for the battery) even though it might only take 2A if fully charged, else soon drop below 10A if not...

Sorry - I delayed my unintentional ramble....

rfhvhtoo wrote:

I just didnt realize how much maintenance you have to do on maintenance free batteries!

I was going to say "but it's AGM!"

But you are correct... Not that it necessarily needs maintenance, but as BetteryFAQ says, ye oldendays setting of 13.6V to 13.8V for cars is too low.
And if sitting or not running (recharged) for long enough...
As to whether to increase or decrease for AGM, well...

You went on to say... "Compared to what you're saying I've been neglecting my battery horribly for about a year now. I need to get it charging ASAP But its my Main battery so I can't leave it charging for days....".
Me saying? Don't you mean BatteryFAQ? Or did really I cover that...? (LOL!)

But it shouldn't need days... overnight should be fine.
Yes, the lesser the discharge, the less frequent the recharge (cycles) etc etc, the longer than battery lasts.
But as per bFAQ (batteryFAQ), crankers are designed for 4 starts per day.
But AGMs aren't "crankers" are they? (bFAQ says what I have said - AGMs do not state CCA or CA. Maybe that's because their internal resistance makes that pointless. But maybe ...)

But you are using for audio. Does that mean you have a dual battery setup, or just one (and in the boot/trunk)?

You should be able to set your alternator voltage to suit the AGM if it is charging at too low a voltage (unless it is a D+ alternator - ie, only the D+ charge-light output, aka single-wire; we ignore the heavy B or B+ & ground).

But it's in non-colocated dual/multi-battery setups that charging voltage can be an issue. The paralleling of wet cell & AGM is a lesser issue. (I always assume parallel batteries are NOT connected when not charging, and when not being used in combination for a heavy load. But there are those that don't care about longetivity and /else dispute or don't understand the other issues bFAQ & I point out - eg, JM & OJ.)

Posted By: rfhvhtoo
Date Posted: December 09, 2010 at 5:33 PM
Yeah its for my car audio as well as the rest of my electronics. the single large battery setup could handle it (back then I only had 1000watts). Now that I have made upgrades in amps and subwoofers over the past yearim near 4000 watts rms. I then upgraded my alternator to 220 amps which ofcourse helped tremendously but can't power my system alone. I've got a stinger voltmeter about 6 months ago inside of my truck actually and is how I'm starting to notice the voltage and trying to learn more about it as I see the performance trickle down. The stinger is always -.2v less than what my DMM reads. I'm starting ask a lot of question now though because When I start my truck it'll drop to about 10.6v and it used to only go down to 11.4v range, and I live in florida so its usually the same 75-85 degree weather isn't that big of a factor I don't believe in my situation. Oh man and I've gotta show you Amazon also has a schumacher sc-1200 with voltage and amp displays for only 6$ more, so many options! But with only 2/8/12 current ratings. But if 8 may be too much ill just stick to the sc-600. But take a look at it anyway before I finalize my relationship with the 600 lol

Thanks for sticking with me through this! Lol

I can't hear you!

Posted By: oldspark
Date Posted: December 09, 2010 at 7:03 PM
Finally - WHY and HOW you want it.... You are making up for too small an alternator or too large a load.
So hence an external charger to the top up required.

Though dual batteries are usually used in your situation (cranking independence and audio performance), that doesn't change the undersized alternator. (You may replace more discharged power, but they still won't be fully recharged.)

In that situation, many people find they replace batteries often - especially those that have 2 or more batteries permanently connected in parallel (battery sales love 'em!). [Hence isolators are well worth it - even if the voltage sensing types (aka smart isolators LOL).]

An any situation, bigger charger capacity is nice IN CASE you ever need a quick charge; emergencies like wedding days etc.

In this situation - go bigger for its voltmeter etc; it is still good bang for bucks - a few more dollars for a larger proportion of capacity increase.
BUT - don't charge at 12A if (say) 7A is the limit for your battery. (Though what if say 8A isn't enough to recharge?)

The recommendation is that you set to the least charge current for the time you have.
IE - if set to 2A and it's charged in the morning, fine. Else 4A etc.
Remember, the lesser the charge rate, the better for the battery. (Reconditioning and maintenance excepted.)   

As to extra price merely for a voltmeter? YES!
IMO a voltmeter is essential - in a vehicle it tells you all you need to know. Except actual capacity - but an ammeter won't do that anyhow.

For a charger, the voltmeter is piece of mind etc. It tells you that it is NOT exceeding specs - eg, 14.4V or 14.5V whatever, or maybe 16.2V for reconditioning (wet cells only).
And upon initial battery connection, its voltage may indicate SOC (state of charge) - but not if or once it has been charged (ie - surface charge).
BTW - SOC is theoretically linear between about 11.3V & 12.7V. (Theoretical? In practice, the battery might hit some level and then just collapse. Modern constant power loads don't help either.)
But for SOC I assume 0.1V = 10% DOWN from 12.7V or 12.6V because that's easy to figure out - hence 11.6 to 12.6V etc. For limiting depth of discharge, that's nicely conservative.
BTW - Darden quoted "about" 2.11V per cell fully charged, hence 6x2.11 = 12.66V for a 12V battery. Hence displayed as 12.6V or 12.7V, but the real voltage can vary through construction differences,temperature, etc.
And for car voltmeters - only ever 3 digits (eg, 12.7V).
4 or more digits for "battery condition" applications. Darden reckons >0.5% voltmeter accuracy. I reckon 8-bits is insufficient (1/256 = 0.4%) but 10 bits is - ie, 1/1024 = 0.1% resolution for digital readers.   

FYI - bFAQ reckons no more than 20% discharge for crankers. I've been saying 30%. But we seem to agree on 50% for deep cycle.

Ammeters are not essential per se (and pretty much useless in a vehicle for any general use!), but IMO chargers should have some current indication.
EG - my 2A/8A charger has 4 LEDs. I see on 8A if all are fully lit and then gradually dim & drop. (At 2A I might switch to 2A to lessen the charge voltage.)
If I know it was flat and it doesn't take 6 or 8A, then the battery is weak... sulfation perhaps.
On the 2A range, only the 2A LED lights (though the 4A lamp may be dim for a while), but that's ok for typical car batteries.   (For small batteries like alarms and motorbikes, even 1A might damage them!)

I hope that helps. Some is POV etc, but hopefully you'll find big agreement between me and the Dardens and other battery "experts" in this world.
For those that think otherwise - it is often a misunderstanding of a basic concept (like only ever paralleling matched batteries, or 12.4V means 52AH remaining), or that battery life or reliability is not an issue for them (eg, permanent paralleling of ANY batteries), or that they really don't know.
To me it seems simple, but I had the luxury of being taught by some some great experienced experts.
As one said, batteries are living and breathing... they are more of an art than a science...
But to quote me, they are still built on a science.

Posted By: rfhvhtoo
Date Posted: December 13, 2010 at 6:26 PM
alright I've been doing TONS and TONS of research looking at different batteries, opinions, isolators, wiring, how much space in my vehicle. I've had this page up for the past 4 days now just comparing and contrasting taking this info into my decisions and plans. And what I want to do is get the charger and 4 RPS Batteries, they are 140ah and the shop selling them for 65$ each. I Say getting these is better than 4000 watts rms on one battery. I Also want to get an isolator between The Shuriken battery (in the engine bay) and those 4 in the back. I'm being told a rule of thumb is 100ah per 1000 watts rms. I'm going to only get 2 at first for 130$ and see how my alternator handles it with an isolator.

My only problems is i've been hearing quite a bit about the reliability of isolators. are there isolators that never allows the front battery to be used with the rear batteries even when the car is turned on? Also about the voltage drop they may cause up to 0.6volts with only car turned on & alternator charging. so it would be 14.4 in front, 13.8 in back. do you know of any isolators that can prove that wrong with tis high current type of system?

I can't hear you!

Posted By: oldspark
Date Posted: December 13, 2010 at 6:51 PM
Forget the isolators with ~0.6V voltage drops. They are diode isolators and are generally pretty stupid and wasteful.

Do you have a charge light? If so, you just need a relay. That relay can drive other inter-battery isolators.   

The 100A per 1000W is simply P=VI or Watts - Volts x Amps where V is rounded down to 10V - often used for input current for output power (the drop to 10V allows for ~20%-30% inefficiency from input to output in amps and PSUs).

What are RPS batteries? Remote Power System?

I can't advise on batteries because you have not provided any reserve time info, but I presume you will get the 500A alternator(s) first?

But 4 batteries (paralleled) is a lot...
I presume you will isolate them when not being used?

And $65 for a 140AH (12V) battery seems very cheap... Are they AGM? Deep cycle?

Posted By: rfhvhtoo
Date Posted: December 13, 2010 at 8:41 PM
He says quote "They are around 140ah IIRC" im guessing the RC at the end is Reserve Capacity.

And no I'm only going to run the 220amp alternator I already have. Thats why I want to only get 2 of the 140ah battery, to see how the single alternator handles it.

These are the type im talking about, just got this pic off of google images.


I can't hear you!

Posted By: oldspark
Date Posted: December 13, 2010 at 10:40 PM
Why did you chose 2 140AH batteries, and not 1 or 4?

PS - based on the only data I can find which is the HRS12-270FR battery (RPS no longer exist) which look the same as your pic...
It is a 75AH battery.

It is a UPS battery with a 10 year design life. That means that in your situation, it may last a few weeks. (UPS batteries are not subject to daily discharges. Many may only see 6 monthly discharges during testing. Some survive only 10 cycles.)

Based on HRS12-270FR data, if all your 220A alternator goes to your amp, 2 batteries will last about 20 minutes (if that - I do not trust their specs; I'd estimate ~10-15 minutes).
You then need to charge them ASAP - the longer you wait, the more they deteriorate.

And I have no idea what you mean by " see how the single alternator handles it".
A 220A alternator handling a 500A load? It doesn't. End of story.
Its voltage drops to the battery voltage and the batteries discharge at a rate of ~300A (which increases as the voltage drops since amp are "constant power" loads - eg, 1680W input is 120A@14V or 140A@12V).

Posted By: rfhvhtoo
Date Posted: December 14, 2010 at 2:15 PM
These kinds of batteries are being used daily in the car audio industry because they are MUCH cheaper. Brands like

C&D technologies (Liberty 1000's)

That specific one I've actually heard A LOT about, many people are looking for these to use but its just hard to get your hands on them. And they are taking these over kinetik, shuriken, yellow tops, mostly i think because of price and you can get a lot of them for the same cost. If I wanted to get That size of battery in the name brands, im looking at $1000+ which makes 80% of people say ill take my chances with he $65 batteries first. I'm not saying they'll work perfectly. I'm actually not saying they'll work at all but $1000 just isn't going to be in the books for a while.

I'm going with 2 because (around 280ah) 1 battery is not big enough for my setup since im trying to completely isolate the front battery from the back so it does not die sooner, or should I take advantage of that battery as well and hook them parallel no iso? And with the 100ah rule of thumb that would mean I need about 400ah in all. there's a $3000 way to put dual alternators in my truck but as I said before it's just not happening at this moment. Trust me i've looked at all the better ways or feeding my system with power and needing the least amount of batteries as possible. Thats why I only bought 1 last year and not 4 at once. Thank goodness i didnt though because i'd rather try it with these cheap 40-65$ batteries before dropping $1000 on 2 XS powermaster 3100's.

But also that is the point of the many batteries is to basically allow your batteries to take MOST of the load. At the car shows like the world finals in Daytona Beach, You see their volt-meter sitting around 12.5-12.9v while their music is playing, because the 4-12 batteries they have in the back are handling most of the load(right?). instead of 1 like my truck is. Many of them still have STOCK alternators which surprises me too.

But Do you really think the car audio batteries are THAT MUCH better though? Thank these cellphone tower batteries (basically).

Here's a manual to the Liberty-1000's (Model# LS 12-100)

I can't hear you!

Posted By: oldspark
Date Posted: December 14, 2010 at 6:04 PM
Now we are getting somewhere... You are misinterpreting what I am writing, and I suspect lots more....

rfhvhtoo wrote:

And with the 100ah rule of thumb that would mean I need about 400ah in all.
What 100AH ROT? Do you mean the "100A per 1000W"?

How longer will those 2 batteries last at full output with the alternator charging at full output - or, how long with & without the alternator?

The rest of what you just wrote is totally consistent with what I have been writing etc. It is nothing new.

BTW - I won't touch Optima either. Not that I'd use an AGM as a cranker (says me with my $650 replacement list price 40AH AGM cranker LOL!).

Posted By: oldspark
Date Posted: December 14, 2010 at 8:02 PM
I wasn't gonna comment, but with afterthought...
rfhvhtoo wrote:

But Do you really think the car audio batteries are THAT MUCH better though? Thank these cellphone tower batteries (basically)...

posted_image posted_image LOL! YOU will once you and the others see how long they last! They are Stand-By batteries...!
Maybe they will last, but I doubt it.
I'm 98% confident that by the end of one year, you'll find it would have been A LOT cheaper buying those other batteries. posted_image

Not that this changes my last reply's question(s) to you (especially what 100AH rule?), but this is firstly a warning.    
Secondly, if other audio buffs are buying those batteries because they "are the same but cheaper", I think I'll be laughing almost as hard as at the cap brigade - but that will take time to show. (I bet these guys use caps top eh?)

I dislike prevention when it prevents a good laugh (and stops money transference). posted_image   (Not!)

PS - Not even Liberty's warranty applies in your case. Don't be suckered into buying one - when it fails, it will NOT be replaced etc.

Posted By: rfhvhtoo
Date Posted: December 15, 2010 at 2:29 PM
lol yes see it's that MAYBE thats getting me!

And honestly im glad (and lucky lol) we're on the same track, even if i didn't fully understand you at first.

Thats just a ROT of a car audio forum in Florida to have 100 Amp hours per 1000watts (not dealing with number of batteries or actually any other specs about the battery at all). And since i dont know how deep into car audio you are, i mean i know you can tell me everything about it looking at specifications and everything and easily crush many arguments i but when talking about batteries everything is about the amp-hours. and I have 2500 watts rms at the moment. so about 250 amp-hours are needed in my situation I've heard many of their cars and they sound amazing and voltage drops are too good to be true so im gonna go with that ROT until i myself can prove it wrong. he is sayinf 130$ for Basically 270 Amp Hours.. I mean thats .50 cents an amp hour! lol I should atleast try it. I'm a big believer in experienced opinions (or that's just a great excuse to try it lol).

I've also noticed that you write 100A, while im saying 100AH. That could be in our misinterpretations as well. OR just how you write it im not sure.

Now for some questions...

Do I need fuses between each battery? I'll have 3 in all with an isolator up front.

Should I do a light charge on them before using?

I'm also going to check the voltage before I purchase them. what should it be around?

Thanks again! posted_image

I can't hear you!

Posted By: oldspark
Date Posted: December 15, 2010 at 6:00 PM
The rule is 100A per 1000W, it is NOT 100AH per 1000W!!!
If the Florida Forum is getting that confused, they need to get their servers out of the sun!

The Amp rule has NOTHING to do with Amp-Hours.

The 100A for 1000W rule is from P=VI where V=10V as I explained earlier.
THAT has NOTHING to do with 100AH for 1000W etc.

If you get a 250AH battery on your load, it will last a few minutes as I explained above.
Hence why I keep asking you how long you think it will last, or how long you want (reserve time) etc.

Using your logic, you don't want two batteries - you want one HUNDRED batteries.
A 100AH battery will supply 5A for 20 hours. It will supply 100A for up to 30 minutes (and if taken to ~10V, will last maybe one year if recharged immediately; though your standby battery probably won't last a month).
You need TWENTY of those 100AH batteries to last 20 hours at 100A.
You need ONE HUNDRED of them to supply your 500A for 20 hours. (Then you'll want a 1,000 Amp charger quicksmart!)
That assumes a C20 rate, but since you haven't mentioned what "time" you require....

You were getting 500A of alternator to handle your load.
Now you are not getting that alternator.
Hence you will be relying on batteries to provide the shortfall.
The question(s) then becomes how will you recharge them? And how long you you want them to last wrt reserve time.

As to how long the batteries last life-wise (as in weeks or years) depends on how you cycle them (how often, to what depth at what rate, and how quick you recharge them) and what battery(s) you buy.

Don't think that people haven't though of cheaper batteries before.
If a Yuasa NP38-12 could be used in place of my UXH38-12, it would cost under $200 per battery instead of over $600.
But the NP might last a few months if that. The UXH is 10 years old and I have already been using for over a year.

If you do want to try it because you believe in "experienced options" provided they are your own, go ahead and report back how it goes compared to my prediction.
If you believe in others experience, let me know.
It seems the Florida Forum is using you as their guinea pig. (I was going to write "sucker for their experience".) Or are they suggesting these standby-batteries from their experience?

LOL! Like I said, not even the warranty will apply in your case.
But I guess it is a cheap experiment (depending on what happens when they fail).

And yes - all battery-to-battery interconnects are fused at EACH end. (Except where physically secure or short.)

Are you using one relay/isolator per battery?
And what sized isolators/relays and fuses are you using?

Posted By: rfhvhtoo
Date Posted: December 15, 2010 at 7:39 PM
Okayim going to reply to the rest of that but I'm on my cellphone and I kind of need that "what should the float voltage be around" question pretty lol like hours, basically I'm wondering where should I be scared?

I can't hear you!

Posted By: oldspark
Date Posted: December 15, 2010 at 8:29 PM
You mean the voltage of the battery in the shops? 12.66V.
And probably no less than 12.40 volts (20% discharged) but even then it could be permanently sulfated.
General accepted ROT is recharge at 3 monthly intervals (wet cells) or 12 monthly for AGMs.

The float voltage depends on the battery type.
Refer to batteryfaq-carfaq section 7.
The rest of that site should confirm what I have been saying - especially section 9 - though it does not get into the details of paralleling batteries and interconnections etc.

Posted By: rfhvhtoo
Date Posted: December 16, 2010 at 7:18 PM

ok purchased batteries from the guy. They are actually used, thats why they were so cheap. I had to meet up with the guy and everything and make sure I wanted them. I checked the voltage of both before I bought them. One of the batteries had just came off the charger @ 2 amp and it was sitting at 13.6v, the other battery he didnt get a chance to charge(why they both weren't charged days ago im not sure) sat at 12.9v. I was good to learn he was selling the batteries just because he was getting out of car audio. Basically to me meaning they weren't burnt out.

No I hooked them up just for some test runs, parallel, no isolator or anything. The alternator charges up to 14.1v and didn't drop below 13.4v the entire time I was testing at full tilt around 1500rpm (i was driving). I'm going to charge them fully @ 2 amps before using them anymore.

its been 2 hours after the testing and disconnected all the batteries from each other and they are sitting at 13.38v & 13.33v while the shuriken is at 12.78v. Would it be smart to somehow COMPLETELY isolate the shuriken from the other 2 batteries to allow them to last longer, not discharging one another? (I'm going to charge the shuriken fully as well before I put the GPS batteries back in there)

And also the the forum is called and they don't even know what I'm doing with my system right now. You are the only person that even knows so far that I have them besides the guy i bought them from lol I dont parade my system around much, i just ask basic OPINIONATED questions on those kind of forums. one of their arguments about me getting to 4000 watts RMS out of ANY amp was with the amp hours. Here's the link to that specific thread. It's basically me just asking what amps work but around page 3-4 they talk about needing 400ah. I looked for more informational threads about it but its basically the same.

I can't hear you!

Posted By: oldspark
Date Posted: December 16, 2010 at 8:10 PM
It's a pity they were just charged.
You were/are measuring surface charge. They need to sit for up to 48 hours, though often less, for surface charge to dissipate. Or load them with headlights etc for a few minutes.

That one of them measures 12.9V after siting for 2 days suggests permanent sulfation - it seems higher than it should be.

And yes, IMO you need to isolate batteries from each other when not in use, but you are confusing battery voltages, surface charge and condition. But I won't repeat my isolator solution yet again.

You said you tested "at full tilt"? That means with the amp on full? If so, your amp is not outputting anywhere near 4kW.

If full tilt means just driving etc, then why would you expect battery voltages to drop or change? They will simply follow the alternator output (except where the alternator drops below the battery voltage).

I see no need to charge them (at 2A or anything) - it seems like they are fully charged.
But you could, and then I suggest a capacity test.
I suspect one of them is below rated capacity.

I see the "100ah per 1000 watts" on 4000 Watts RMS amps #42... LOL! I wonder where that rule or quote comes from? Is it a joke, or a misunderstanding? IE - does long420 base it on something, or is he a sheep or an idiot?   
I thought you actually had it right, but I see now that you quoted 100ah, not 100A per kW. I took that to be a simple misprint etc - I'm sorry now I didn't pick it up earlier - but I was asking "timing" questions instead.

I recall that forum from something else - I think aluminium versus copper (bussbars). Yep - so many fracken idiots that simply miss the point....

PS - If you can, charge the Shuriken; then note its voltage and how fast it drops.
You can do that in the car. After a run, kill then engine, disconnect the -ve terminal, then measure the voltage at intervals. It should start from ~13.8V and then maybe drop less than 0.1V per hour.
Do a similar comparison with the other batteries (but after whatever charger you use).
You could also try running your car on one of the new ones for a while. But carry the Shuriken as a spare!

Posted By: rfhvhtoo
Date Posted: December 17, 2010 at 2:04 PM
Yes from my amplifier right now I DO NOT expect 4k watts... why? its only rated 2400 watts AND I didnt have the electrical to power it. I dont think I said anything like that. If you're bringing what I was talking about from the other forum to here then you read that I was going to get TWO of the amplifiers I have now. I'm about to start running this amplifier @ 0.5 ohms (hence why i got the extra batteries as well). They calls for a 200amp external fuse and ACTUALLY stopped producing power with a DMM at 60.2volts AC.Voltage would only go down from there. Honestly I dont know if that matters to you or not, just some fun facts lol

"Full Tilt" means the volume of the radio MAXED out and the amps should be maxed out if the gains are set correctly. And when i say 1500RPM's because that is at where i reach at a steady 45-50 MPH on the road that i can turn it ALL THE WAY UP (aka full tilt). and the voltage did not drop below 13.4v. when before it was an easy 11.9v. Come on im not that far behind I know NO load will not drop the voltage. lol

Only the shuriken was at 12.9v which is the one battery i've been using this entire time, I want to ISOLATE THAT battery from the RPS batteries. and the shuriken battery has NEVER been charged so I wouldn't doubt the permanent sulfation.

I mean i would think it's better to charge all the batteries to full potential before putting them back in the truck. also people talk about batteries that have lower voltage than the other trying to charge themselves on the higher voltage battery? And that's the reason people say to get matching batteries or batteries around the same age for that reason. I am just trying to make these batteries last as long as I can. If the automatic charger is going to make sure they are fully charged for 25$ then why not? I've gotta beat your 1 month prediction lol

and I will run that test you suggested ont eh shuriken hopefully today.

I can't hear you!

Posted By: oldspark
Date Posted: December 17, 2010 at 3:01 PM
So are you designing for 4kW output or what?

I suggested the "12.9V after 2 days" battery you bought is sulfated - not the Shurikan.

I suggest you ignore that crap about 100AH per 1000W. It first appears on that site in Jan 2010 but there is nothing about where it is from or what it is based on. (And I could not find it anywhere else.)
Until that is known, treat it a bovinepoo - as a misquote of the 100A per 1000W rule.

And I'd love to know why they keep recommending more batteries rather than a bigger alternator!
(Yes I know "it makes a big difference". Have any of them said an appropriate alternator makes more difference? I can never understand why people recommend bigger batteries when they wouldn't even be used with a bigger alternator! I reckon they're probably idiots that got that batteries first 'cos that was said. They then figured out that just meant a longer to flatten, and the cheapest charger is an alternator anyhow.)

I'd be very wary of other advice and products on that site. I love that Crescendo 3K spec - it's another one of those amplifiers with greater than 100% efficiency! (Based on their recommendation for an external 300A fuse since they do not provide a fuse.)
But by their own specs, the Crescendo is crap anyhow - how do they vary their output power so much with varying input voltage - an input-proportional SMPS internal rail?   

But if you got that Crescendo 3k, you would obviously be getting a bigger alternator and not worrying about the batteries wouldn't you? (Since that will make 2 Volts difference.)

But I've done all I can for now. I have accurately predicted what you have found or consistently confirmed it. I have stated what you need for what you were designing.
Until you provide answers, there is nothing more I can do.
I might hear from you in a month? Else whenever the new (2nd hand) batteries don't meet their reserve time.

Posted By: rfhvhtoo
Date Posted: December 17, 2010 at 3:25 PM
lol alright buddy thanks alot it's been nice working with you!

I can't hear you!

Posted By: oldspark
Date Posted: December 17, 2010 at 6:50 PM
Just do me a favor and find out WHY they recommend what they do - ie, adding batteries.
And ask what "time" they base their 100AH per 1kW rule on. As you said, you had a 220A alternator.

Also, if you are measuring 60V AC, you have got BIG problems - unless from an amp (ie, max theoretical 3600W RMS into 1 Ohm?)

And a 200A fuse for each amplifier means that they too are NOT 2400W RMS output, but that is already suggested by your tilted non-voltage reduction.

And you are no doubt aware that your voltage will reduce with RPM - the alternator profile will handle that. (I think even those FloridaSPL lads recognise the problems with rewired standard alternators - or was that another forum with a wise norseman who rightfully suggested more batteries for SPL comps; he even wrote why NOT to use caps! Not bad for a non-eng soundie.)

We also have different opinions as to what work means.
Can you hear them laughing too? (Regulars know how I'll get mine... - and got!)

Posted By: oldspark
Date Posted: January 25, 2011 at 7:10 PM
The post-month revisit - refer to rfhvhtoo's relay or isolator page 3 - curious to see if the batteries lasted (if they only need recharging once a month, why bother with them at all?).

And still no info regarding this "100AH per 1kW output" rule.
I bet it was from an idiot or a battery salesperson!

Posted By: rfhvhtoo
Date Posted: January 25, 2011 at 7:50 PM
heyy!! alright look i'm not sure If I told you that I did run a mild .66ohm test with and without the 2 batteries with my old 3 10 inch setup (which is now sold). I'm sure just as we expected you know the amp sounded much better since it has alot more battery power to use with the 2 140's ah as well as the 100ah shuriekn totaling 340 ah... Now The since I was already planning on upgrading speakers and amps, I had a buyer that wanted the speakers asap So i sold those faster than I could buy my next setup. The Batteries havent been used for about 1 month exactly now and they are sitting at 13v. I've charged them once already late december and the initial charged percentage was 98% for both of the RPS while my shuriken was at 67% =/. I bought a 300amp relay that I'm going to be installing when I install my system.... but I did want to ask you. Would it be better for me to have the RPS batteries charging on my alt daily? even though I dont have anything hooked up?

I can't hear you!

Posted By: oldspark
Date Posted: January 25, 2011 at 7:59 PM

Posted By: rfhvhtoo
Date Posted: January 25, 2011 at 8:03 PM
What's the reasoning behind that?

I can't hear you!

Posted By: oldspark
Date Posted: January 25, 2011 at 8:16 PM
No self discharge.
The more you charge, the quicker the battery dies.
And you have standby batteries - not cyclic.

Keeping on float is different - that is ok.

Posted By: rfhvhtoo
Date Posted: January 29, 2011 at 11:42 PM

This site is saying that AGM Batteries are good for Bursts of amps. That sounds awfully close to high amp bursts of a subwoofer amplifier...?

I can't hear you!

Posted By: oldspark
Date Posted: January 30, 2011 at 3:23 PM
Yeah - and it says you can use standby AGMs as opposed to cyclic AGMs? I don't think so....!

And it says "AGMs can supply bursts of power therefore they are designed for that"?   (The point being that for cranking, apart from a rare few, AGM manufacturers do NOT specify CA or CCA. Why is that?)

Your link is a quick and general overview. It barely discusses charging.
The link I gave you includes the points I made above and in your other thread, plus most else I have told you.

Unfortunately your "theory" is entirely arse about - even starting from the "100AH per 1000W" which is an misquoted alternator/load rule - an telling people to use batteries when the alternator is the solution! (You need 100A of alternator per kW of load, NOR 100AH per kW of load!)
If I am wrong, show me the source or reasoning of the "100AH" rule. Nobody has yet even stated reserve time!!

rfhvhtoo wrote:

AGM Batteries are good for Bursts of amps...
And YOU know why AGM batteries are good for delivering HIGH currents don't you?

Posted By: rfhvhtoo
Date Posted: March 16, 2011 at 3:11 PM
Wow, is really all I have to say so far. I've had the Batteries for about 4 months now. Allow me to describe them, The first 3 months I sold my system to start a rebuild so they sat in(side) my truck, with weather down to 20 Degrees throughout the winter nights for 2 of the 3 months. With florida having unpredictable weather there has been many days of it being +90 Degrees and they sat at 13v the entire time (they are stand by batteries so we kind of expect that right?). I charged the Batteries once in December as I posted before. I put in a experimental system about a month ago that I wanted to practice my box building with (some old 10 inch speakers i had). The box is great I might add posted_image for my first bandpass enclosure. I have the same Hifonics running @ 2ohms suppose to have approx. 1600wrms and my Volt meter (and DMM) RARELY drops below 13.5v during play. The only times I've seen it drop that low is when there is a High(er) Frequency bass note plays SUDDENLY (at high volume) while the alternator is at idle (parked) and not charging as High at the moment, but it quickly recovers DURING the play of the 50-100hz frequency and will sustain back to 14.0v. This is with 2 of the ($65) 140AH Batteries and the 100AH Battery in the Engine bay, 1 300amp $18 Relay and 220amp HO Alternator .

My theory on it so far is, The Batteries will not go bad, or discharge, as fast as you think simply because the goal is to NOT Discharge the batteries as much as possible. But instead to have more batteries So the current draw will be less taken from each battery instead of all from one battery.

And with the alternator charging the batteries up to 14.0-14.2 are they being Discharged at all? especially if the current draw is below the rating of the alt?

I can't hear you!

Posted By: oldspark
Date Posted: March 16, 2011 at 9:22 PM
I love your theory. It sounds on par with floridaspl's level of expertise. And their logic.

My theory is that your goal to "... NOT Discharge the batteries as much as possible" is irrelevant. It is the implementation and reality that counts.
Besides, floridaspl say you MUST have those batteries, therefore they are being used and discharged. Right?    

Another theory is that you are not loading them (hence not cycled) as evidenced by your voltage readings.    

I hypothesise that you are also not loading anywhere near the 4kW we were discussing and designing based on your criterion.

The storage and the temperatures you describe should have no effect on them. Their voltage should only drop by (say) 0.1V after a few months.

Your reasoning for more batteries to de-stress the batteries is sound (pun intended), but what choice do you have...?!
You did as many "audio" forums advise and got more batteries instead of a copious alternator. What can I say? (See NOTE.)

But all this battery stuff is total crap anyway. To quote a floridaspl 8,000 poster (with that count I assume they have knowledge?), they "lost maybe 2 tenths from 13.8 to 11.9 v"... - ie, they only lost ~20% of power from 13.8V to 11.9V. (It's over 1/4 or 25% in reality, but who cares?)

And another reckons "... a drop in voltage means no difference in output..." which is true if amps were constant power loads like most SMPS equipment.
However, from the specs for your and others amps, they are resistive devices - their power output is proportional to the input voltage (squared).
[ BTW - I love how the latter later wrote "A drop in voltage would only create a larger draw of amps. The problem is you can't supply the larger draw of amps and this is why you have a loss in output...". Oh my dear Poos & LOLs - that cracked me up! But they were a mere sub-400 poster after all. And that stuff is very confusing to the inexperienced, and still difficult to explain... ]   

NOTE - the above is what I can say.

Have your theories, but maybe keep them off-site - maybe on floridaspl where they belong for now.
Come back when you have solid experience to report - there is no use arguing beliefs against reality unless you want retorts like "I wrote you so..... MANY times!" (Like others I usually refrain. Certainly in my case it's hard enough controlling the fits of laughter. Or - alternatoratively - the tears.)

Meanwhile I wonder if floridaspl figured out whether a cap stores current or voltage? And whether a cap's voltage is ever higher than the wiring & equipment it is connected too - they certainly make it sound like it is - but it is a sound forum!).
(I was surprised to read that only big caps hold their "zap"!)    

But I suppose audio forums like floridaspl will continue to not only counter the experience and logic of others, but also contradict their own writings and logic. (Here we have differing opinions and priorities/tacks but technical contradiction are rare.)
Who sponsors them?

Meanwhile floridaspl post counts mount up by people that repeat what managers or experts from elsewhere claim - except that what was said is misquoted or twisted out of context (if it ever was said LOL).
It's like sharks being afraid of dolphins and AGMs being ok to supply big current.
But lots of medicos, battery suppliers, and other support people make money off those that can't know any better. Being into Quality (more so Demming than Darwin) doesn't mean I should risk livlihoods.   

I guess you still don't know where the 100AH per kW comes from? If floridaspl had the experience to back it up, they'd be using caps instead. Or are they referring to battery reserve time?
I wonder what BigBoi would say? But maybe others haven't been exposed to REALLY big systems and thence know why a cap is needed... I still reckon the 100AH/kW is some twit's misunderstanding of the 100A for 1kW rule. Honestly, if they meant 100AH per 1kW, they would be specifying Farads! (Or did I kill that one too by asking up-time?)

And you don't know the difference between a stand-by battery and a cyclic battery???

With luck I'll see you about one month after you start using your system when mobile with at least 1kW output; and after recharging your extra batteries once a month at home.

Thanks for the monthly update, but until you complete the system, a simple "still progressing" might be shorter.

rfhvhtoo wrote:

...13v the entire time (they are stand by batteries so we kind of expect that right?)
WRONG! (ie - wrong reason.)

rfhvhtoo wrote:

And with the alternator charging the batteries up to 14.0-14.2 are they being Discharged at all? especially if the current draw is below the rating of the alt?
LOL! Should I even bother answering?
Or can you explain why an alternator would be up around 14V if it can't supply the current?

Posted By: oldspark
Date Posted: September 05, 2011 at 11:52 PM
rfhvhtoo - still progressing?

Or have the batteries been subject to the 4kW RMS amp(s) for reasonable bursts and runs?

Posted By: rfhvhtoo
Date Posted: September 07, 2011 at 9:52 PM
oldspark wrote:

rfhvhtoo - still progressing?

Or have the batteries been subject to the 4kW RMS amp(s) for reasonable bursts and runs?

The two are doing really good actually, with the 220amp alt, 2-140ah & 1-100ah in the engine bay the voltage does not drop below 13.3v at idle on the stinger voltmeter. My DMM reads 13.5v but I like to under estimate, even if it is with the worse device (stinger). The 2 in the back are still sitting at 13.1v as usual, but my front battery has been going bad since before I had the new batteries. so Its still sitting at 12.7v. I was thinking about just getting a new acid lead battery for the engine bay since I have the Relay between the engine and the 2 in the back. For one it's cheaper, and all I need it to do is really start the truck, and be a good battery.

no bad reports at all. if there's some testing you want me to do let me know! :)

and the voltage tests were on Music and Bass tones to set gains on the Hifonics BXI2408D. I have it at 0.5ohms. efficiency of MAYBE 50-60%? From the bench tests I've seen the efficiency is less than 65% at 1ohm on these amps. So it should be pushing around 2800-3000watts at that efficiency. which is About a 400Amp current draw.

I can't hear you!

Posted By: oldspark
Date Posted: September 07, 2011 at 10:15 PM
Still below the 4kW....
How much running on just the batteries alone?

Yep - stick to wet for cranking, much longer life and better suited.
And when charging, parallel AGMs with wet etc won't matter.
And with the voltage drop you mentioned (if accurate), a low ESR front battery is wasted.

Posted By: oldspark
Date Posted: March 05, 2012 at 5:54 PM
rfhvhtoo - How now? Still progressing?

Have the batteries been subject to your original 4kW RMS load for reasonable bursts and runs, and how have they fared?
Do you top the batteries up once a months, or do you need to after every use?

If you haven't got the 4kW RMS load installed and use it on a regular basis, there is not much point responding.
Although if your standby batteries failed (or not) - especially if in cyclic use (with say 20% discharge or more) - I'm interested an your reply.   

Posted By: rfhvhtoo
Date Posted: March 07, 2012 at 1:29 AM
I travel in my truck a lot so I usually drive about 1-3 hours with my radio up (80%) Volume. This is my Equipment right now

Lanzar OPTI500X2

I have this running @ 2ohms each channel 750Watts x 2. ( four internal 40amp fuses)

HiFonics BXI2408D

Running @ 0.5ohms, Bench tested at car shop to a solid read at about 2650 Watts so I say 2500Wrms. (one external 200amp fuse required)

Rockford Fosgate T3002

Running @ 2.66 Ohms and its "Actual rating" from the rockford birthsheet @ 4 ohms 163watts x 2, and @ 2ohms 278watts x 2. (two internal 40amp fuse)

So I have about 4500Wrms. 440AMPS worth of amplifier fuses

My Voltage never drops below 13.3v, the alt charges to 14.2v.

My RPS brand standby batteries are sitting as of LAST WEEK 13.1v, and my front battery that was going bad last year (the shuriken) is sitting at 12.7v.

I haven't charged any of the batteries since I charged them last January iirc.

SO I can say they are doing GREAT posted_image

What do you think?

I can't hear you!

Posted By: oldspark
Date Posted: March 07, 2012 at 2:46 AM
Well it sounds like you don't need the batteries - they are barely being used.

It seems that you have an alternator rated for at least 300A (or 2 x 250A or 2 x 160A etc) - somewhat more than your original 220A alternator.
Is that correct?

Pushing 2650 Watts or even 2500W RMS output with a 200A fuse is pushing fuse specs. Running at 80% (of power) should be ok provided it's at 14.2V, but not at 13.3V (80% of volume is even better.) But at full output, you're likely to replacing fuses relatively often.
The shop test (if using a 200A fuse) was probably relatively short (15-30 minutes max) and maybe they used a higher voltage in their tests...

Incidentally, 440A of fuses should be okay for ~5500W output @ 14.2V, or ~5150W @ 13.3V depending on the actual fuse specs. (That assumes a 110% overload won't blow them, though they will run very hot and fail quicker through thermal cycling. 120% overload is often a 1-hour fusing time.)

Have you run the system without the extra batteries, or reduced the number and compared the effect?

And did you ever find where that "100AH per 1kW" rule came from? (As I recall, it was essentially only floridaSPL that quoted such that rule, and without any battery type or size qualification etc.)

As it stands, your system is not as originally proposed, hence the batteries are not being cycled etc etc.   
But good to see that you alternator was upgraded - even to the 220A. I can't understand why people add batteries BEFORE upgrading the alternator.   (Then again, if they reckon put the batteries in the engine bay for extra capacity, they obviously have the money to spend on more batteries!)   

Thanks! for responding.

And may your ears last. Trust me, hearing grasshoppers 24/7 is a pain in the ears. Well, it's damned annoying anyhow. posted_image

Posted By: rfhvhtoo
Date Posted: March 07, 2012 at 2:33 PM
yeah thats what I was explaining before, that I would not be draining the batteries by much. And no its the same alternator just added the 2 RPS batteries back in January.

With the shuriken battery alone, I was dropping to 12.5v at 80% volume, and THAT was with only the rockford and Hifonics. Not with the 1500watt lanzar.

And the 100ah per 1000 watts is only a rule of thumb. There's no cite for that.

But thank you and If ANYTHING witht he batteries go wrong im coming to you first lol posted_image

I can't hear you!

Posted By: oldspark
Date Posted: March 07, 2012 at 6:39 PM
Yeah, and hence not using them anywhere near what was originally envisaged. If they were, my bet is they would not last long. (Under your original conditions, you would have had to recharge them externally after every use (else engined with audio down or off), not once a month.)

But keep in mind that the 100AH rule is not a ROT - it is a rule that seems peculiar to floridaSPL only, though by now it will no doubt have spread. I could probably start an equivalent rule of 10AH per kW, or 1,000AH per kW, and double those for wet cells or gels.
I still reckon it is a misquote or misunderstanding of the variously used 12V rule of "100A per kW" - ie, as a simple guestimate of current, or a design-safe estimate of load current, or an approximation for fuse (or cable) ratings and converting output power to input power currents (ie, assuming ~80% fuse or cable rating margin, or ~80% amp or equipment efficiency). But the 100AH per 1kW ROT has many more variable attached to it (eg, battery size, ESR, charge state, temperature, age).

Just be careful if specifying standby batteries for audio and cyclic use. If they are truly needed and discharge regularly, they probably won't last long.   
[ Getting back to your original "batteries are batteries" comment, they aren't. With some batteries being 1/10th the price of others, money hungry companies and misers like myself would be sure to use them. But trust me, cranking batteries used for solar (or vice versa) are unlikely to last long. And industrial UPS would be using ordinary batteries too (though some UPS batteries may only last 5-10 cycles, but they are more stable/reliable and smaller).
A similar situation exists with ordinary domestic batteries - cheapies may last longer than alkaline, or as I found, those $5 Lithium 680+ AA & AAAs are far cheaper than using 20c-$2 substitutes in cameras. ]

And as you are probably aware, if using low ESR AGMs with thumping hi-powered audio systems with higher than a few kW output, caps of 1F or more will probably extend the life of the AGMs considerably. (Wet cells do not suffet the same problem. As I oft write, AGMs may be capable of supplying high currents, but they don't like it.)
That - apart from battery time lags (and ignoring surface charge) - is probably the only legitimate application for caps in quality audio systems.   

FYI - I often refer people to Bill Darden's BatteryfFAQ - IMHO an excellent & well written reference - everyone should read at least 1. WHAT IS THE BOTTOM LINE AND TIPS?.
It's a relative easy read considering the complexities with IMO the most useful section 9 being the only big section.
I suggest downloading as per 9. HOW CAN I PRINT THIS FAQ?, and maybe checking every few months for the occasional update.
But you should find that I write agrees with Bill, though that detail may not be so obvious. (And as I often lovingly write, he cleverly passes the paralleling of batteries to others, though again, BatteryFAQ does contain all the raw facts involved.)   

Finally, thanks for your last comment.
Though not quite the conclusive thread I was hoping for (I think you were lucky else fall short of the original design conditions - hence the importance of realistic normal operating conditions versus worst-case operating specs), I have noted your success as a future reference.   
Besides, maybe those standby Shurikens are capable of much more - just as my 12 year old Yuasa 38AH UPS battery has survived years of cranking and auto use which - IMO - it shouldn't have. In fact based on a few experiences, my guess is that a Yuasa UXH100-12 or UXH110-12 (100AH or 110AH, 12V) is not only cheaper than the smaller ~70AH Optima equivalents, but will far outlast the Optimas. As to physical robustness, several months ago I dropped my current UXH38-12 about 1m (1 yard) onto concrete, hitting corner first - not edgewise of flatly. Even I was impressed - my first instinct was to run!! And I like dirt roads and speed up to "smooth out" holes, corrugations, and rebel against speed humps, so vibration & shock - at least for the UXH38 - seems not to be a problem.

Anyhow, congrats and all the best.
Let me know if the Shurikens fail "prematurely".
And beware those grasshoppers, or occasional crickets or cicadas, or opera baritones and ringing that also get reported. (LOL - but as my serious tip.)   

Oh well, yet another typical short reply...


Posted By: rfhvhtoo
Date Posted: July 26, 2012 at 2:49 AM
Nothing has happened to my amps or anything... but I finally understand what you're saying. Batteries are slow. People in car audio are being saved by batteries, we're just getting jipped for more money and its actually worse. Advertising is brain washing! Lol

I can't hear you!

Posted By: oldspark
Date Posted: July 26, 2012 at 4:02 AM
What do you mean "Batteries are slow"?

And how are you being jipped for more money?
Have yours failed (I take it they haven't) or do you mean that they advertise that you need expensive batteries when your cheap ones work fine?

Posted By: rfhvhtoo
Date Posted: August 01, 2012 at 2:49 AM
Well I'm basing that idea on a completely different topic. What are your thoughts on Capacitors, and do they have a place in car audio to you?

I can't hear you!

Posted By: oldspark
Date Posted: August 01, 2012 at 3:08 AM
It's better not mixing topics.
The delay for a battery to change from charging to supplying is one thing, but it isn't meaningful without considering its surface charge and capacitance, nor comparing to the instantaneous amp output.
As to wet cells being slower than AGM, or slower thru thinner cable... (That's supposed to be a joke.)    

As a Rule of Thumb, capacitors for car audio belong in the bin along with brainwashing and money jips.

If you want higher peak SPLs, do not use capacitors. (That's based on competitor's audio forum and elsewhere advice.)

The only definite use for caps is in BIG audio systems where AGMs are used, and that's only to protect the AGM battery.
That typically applies for systems of about 3kW (RMS!!) output with maybe only one adjacent battery - ie, it's not required if the AGM is remote or in the engine bay, or if there is more than one adjacent AGM (of sufficient capacity). (Scale that up for bigger systems.)

Posted By: rfhvhtoo
Date Posted: August 01, 2012 at 10:56 AM
Well I just didn't want to start an entire thread on a question that is asked thousands of times a day. Do you just want me to start a new thread, because I have a debate/argument to kind of play devils advocate on this one. posted_image

I can't hear you!

Posted By: oldspark
Date Posted: August 01, 2012 at 4:11 PM
I am the devil. I am one of the few (or the only) on this site that advocates caps. But as a way of "holding up" voltage - FORGET IT (do the calcs!) - unless you cannot use an adjacent battery, or for headlights etc.

Start a new thread, but search to see if you're repeating the same...
And if you are getting your info from the guys that suggested batteries BEFORE the BIG-3 or upgrading the alt (to cover your amp output), then what can I say (I've already said... numerous times).

If you don't believe me or this site, try Richard Clark's articles.

But certainly, a new thread if you still have any doubts.

Posted By: rfhvhtoo
Date Posted: August 01, 2012 at 4:16 PM
Okay, if I HAVEEEE to... ill call it the truth behind capacitors & car audio (hopefully).

I can't hear you!

Posted By: rfhvhtoo
Date Posted: August 01, 2012 at 4:25 PM

I can't hear you!

Posted By: oldspark
Date Posted: August 03, 2012 at 8:45 PM
Well done, it's been locked. (And I don't disagree. It's a waste of the12volt resources repeatedly dealing with simple fundamental understandings.)

When you understand or don't understand published info on what you are asking, then maybe start a new thread, and supply that info source (link and extract) as well as what your specific question is else how you understand it.

If you can't understand what sources are saying (like my links in your cap thread) then I suggest going a step lower - eg, a capacitor-101 course (maybe and similar).

If you have a specific real problem - like your audio output is dipping at certain times - then a new thread describing your problem, your set-up, and what you want to achieve. But make sure you have appropriate wiring first(the BIG-3 etc, and a copious alternator), that's saves a common standard reply from us.

FYI for a laugh - I recently read a site where someone added a battery or cap or something and the wrote "I'm glad I did that before upgrading the Big-3 etc" . I cracked up! (I think their solution was more expensive than the big-3 besides which, if needed, the big-3 is a fundamental requirement. It's like the tarmac on an F1 or nascar track assuming you want speed, or minimised voltage drops and max power etc for electric power situations.)
But that was in some "car audio" forum, well known for caps first, then batteries, and then and alternator. IMO that is totally inverted (just like an SMPS-powered amp that for reasons unknown outputs less power with lower voltage steady input!).

Posted By: oldspark
Date Posted: August 05, 2012 at 3:09 AM
Not wanting to hijack this thread due to your other (locked) thread etc, but I just read of your University learning.

You can therefore provide digital scope outputs else pics that support what you are saying, eg, caps discharge and recharge many times etc, or that caps charge "faster" than batteries. (A batt may only recharge 1% in a second, but that is still far more capacity than a cap. My battery recharges at 40-45A after cranking (I have a 90A alternator instead of its OEM ~20A generator) and drops to under 10A after 1 minute. Take any time segment therein and tell me what cap has recharged with an equal or greater capacity.)

Also, have you had any of the relevant University teaching staff concur with your writings (maybe Bobby Fox or Jane, even Scotty or the Ant)?
If so, please let me know!

If not, have you approached them to explain what is happening etc?
They should be able to fill the gaps that we are unable to make you understand. They should at least know the basic theory (which contradicts your conclusions) if not the actual application.
They might even explain which way current flows (ie, both).

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