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do i need a high powered alt.


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oldspark 
Gold - Posts: 4,913
Gold spacespace
Joined: November 03, 2008
Location: Australia
Posted: November 07, 2012 at 3:07 AM / IP Logged  
Interesting statements considering the yellow has similar internal resistance and therefore should crank the same. (I'm looking at a yellow .0025mR spec versus the .003mR for the red, but they may be different capacities).
And the yellow may have higher terminal voltages (for reasons unknown).
But their internal resistances are for fully charged batteries (of course!) and can't be used for real recharge current data. (Internal resistance increases with increasing discharge level. Just as well, otherwise many flat batteries would explode (not really...) or wreck far more alternators!)
And charging limits are the same, ie, 10A unless under ~50C when no current limit applies.
But crankers are different to deep cycle by merit of construction - ie, for the same size (capacity?), high-current crankers have more thinner plates and hence more "current area" whereas deep-cycles have fewer but thicker plates to handle the greater discharge depth without as much plate damage.
And other batteries fall somewhere between the two high-current and high discharge-depth constructions.
And of course a big enough deep-cycle can supply adequate cranking capacity without significant damage. Conversely a big enough cranker can deliver a smaller deep-cycle's long discharge AH capacity (but still remaining within low %age cranker discharge depth limits).
Though the above is almost common-sense (once you realise it), I am often surprised at some battery discussions. People may discuss the same battery but with its 2 different specs for differing applications. One simple case involved an argument between a 7AH C-20 and a 4.2AH C-1 rated battery for the same application, yet they were the SAME battery!
I thought audio forums took the prize, but others are well in the running too - like the authoritative or respected dude that was pooing the efficiency of using a battery by testing what it took to replace the same charge it delivered - but at 12.7V! (IE - he recharged at 12.7V since that's what the battery was. Do not pass Go. Don not collect any money.)
And they are often full of the same "must match batteries when in parallel" for systems that have auto-isolators (ie, only paralleled when charging or required).
But some audio forums probably take the lead all things considered. By that I mean combining all their snippets into the overall system.   
Some readers may have read threads hereon by someone also on a certain south-east stateside audio forum. There were statements like housing batteries in the engine compartment for greater capacity due to the increase temperature (they must have at least started with lots of money...).
There was also a rule like 100AH per kW of audio. I could only find the first post with that statement, but never found its source or what it's based on. I suspect it's someone's version of the oft used 100A per kW (for 12V systems).
I suspect too that a certain "Farads per Amp" rule is likewise a twisted application of another general power rule of 5-10uF per Amp or 10,000uF per Amp depending on how you engineer it. I'm waiting for the day that someone quotes a source or basis, and thereby probably declare that all this cap stuff it for a certain voltage dip after a mere 10mSecs. Whilst I know that that short time may have some possible validity compared to batteries, I suspect most others will not know that connection. (Sorry for the double may & possible, but the latter may have validity wrt to one "theoretical" aspect of battery behavior, but I suspect it ignores another practical and real aspect.)
However that short time blows away any arguments for caps with burps lasting more than a fraction of a second, and then the battery continues and wins hands down (yes, even a $15 1.2AH).
Despite the above "general" rule I mentioned for 10,000uF aka 10mF per Amp, I know that some "quality" amps have 1mF per Watt of output, but that's a SMPS level - not the raw DC input level. (But that's where to add extra capacitance - NOT at the DC input level!! Not that money spenders are told that, or provided that option (though I understand why).)
Some know my views on how big amp design is totally flawed anyhow. IMO it's so stupid having the PSU in the rear-mounted amp instead of placing the PSU near the alternator and main battery and thereby distributing at least a ten-fold decrease in current to the amp(s) depending on local Regulations and their interpretation.
But there is so much money still to be spent on the current architecture (good pun eh?) that it may be a while before the split occurs. Of course multi-battery audio installations probably prefer the current method, and the long proposed conversion to 42V vehicle systems make the split system less attractive.
Geez, I kinda digressed, Again.   
Did I mention the local SPL competition I attended? (No - only about disconnecting caps for higher peak SPLs?).
I noted that all the vehicles except for one used wet audio-battery banks. And no - the AGM did not win.
And I barely noted any caps. Mind you even the AGM vehicle had more than enough AGMs to not require that (for AGM potection; there were about 10 or more AGMs).
I've been meaning to go back to the store that hosted the event and discuss the issue. Maybe one day... Maybe one day I'll also mount my single speaker and beat the lot of them LOL! But why add to my already jeopardised status?
But my point is that maybe the locals agree that caps decrease the peak SPL. That may also account for their use of wet cells.
Anyhow this reply started with aspects of Optima battery ratings. I guess the recent posts have resurfaced some old discussions.
BTW - that "SE-audio" member recently reappeared to discuss capacitors. I suspect he had some new found formal education that spurred him. Unfortunately he lost sight of - or failed to understand - some simple basics about when capacitors charge etc. It wasn't long before he got into formulae etc which were at that stage far from relevant. In some ways that reflects some common forum discussions - too little knowledge, or too new and specific detailed knowledge that has yet to mature.
[When I consider what I've just written, I realise the multitude of experience albeit "electrical" whether it be batteries, or the tiny (if any) capacitance required for high-frequency power conversion (ie, SMPS). Some of us know that an inductor complements a capacitor, yet rarely is inductance discussed. (Ah - that might be the next revolution - high inductance oxygen free cable!).]
And FYI - a great source for battery info that I oft recommend is Bill Darden's batteryfaq.org.
It's usually revised every few months (albethey minor - the basics don't change much), and now the downloadable Battery.Zip is listed on the home page rather than its old buried location in chapter 19.
I can't recall if Bill goes much into some of the AGM-dislikes that I have mentioned though I suspect it's readable between the lines as so much of battery detail is (ie, once you understand it, you realise something is covered in his writing), but he certainly did IMO palm-off aspects of paralleled batteries to elsewhere (clever Bill!!), though IMO that too is contained in his writings.
Maybe you suffered all the above for that link. Or did you just jump to it LOL?
And BTW again, great that your red top has lasted. It should last several more years.
I remember when I considered 3 years a good life for my wet batteries. But with better battery technology, and my move to improved vehicle electricals (especially the relatively recent conversion to all-in-one alternator-regulators, and maybe too the in-dash digital voltmeter), I now expect at least six years even with my abusive behavior.
lurch228 
Silver - Posts: 1,338
Silver spacespace
Joined: August 08, 2012
Posted: November 07, 2012 at 4:21 AM / IP Logged  
"oldspark"
Since you believe so strongly in what you say and have learned over the years.
How about you opinion of Hybrid Battery Chargers and the like?
I follow you on most of your beliefs, but differ on a few or have had positive experiences with what I have used and how I used it, maintained it and the like.
I don't know everything just what I've learnd over the years based on need to do it myself and not pay some one to do it for me. My knowledge may be limited to specifics that I needed to learn, but I try and continue to learn along the way. I could never be an expert in any one area as I am to diverse in any thing that I can do myself, with research and planning I get what ever I set my mind to done.
oldspark 
Gold - Posts: 4,913
Gold spacespace
Joined: November 03, 2008
Location: Australia
Posted: November 07, 2012 at 7:05 AM / IP Logged  
I'm not sure what type of hybrids you mean.
If it's domestic cell hybrids, they aren't lead acid.
Hybrid technology still follows battery basics.
Hybrid cars ditto whether lead acid or lithium etc, or thru regenerative braking. And hybrid cars should not need ancillary charging - except for long idle periods
I don't think I'd have anything to add to what others say, just on what I'd sense as obviously wrong or inconsistent, or overkill or expensive or under spec, etc.
Not that I believe strongly in the above nor my previous posts. It's merely that I believe them to be correct, and then write to help others, or prevent waste, or promote understanding (including my own!). And my statements may have differing degrees of correctness about them. Besides, learnings do evolve.   
My knowledge too is largely what I needed to learn education and career wise, but there is a lot of ancillary stuff too whether thru hobbies or just plain luck meeting the right sources in areas of non-interest.
I know what has worked for you, but I'm trying to quantify that wrt to something tangible, or compare it to cheaper options with seemingly superior results.
I have been driving since Easter with no rear brakes instead relying on only the two fronts (which have the same shoe/lining sizes and drum diameters as the rears) and that has worked fine for me. Whether I'd claim or suggest it is as good or better than having all 4 brakes - let alone recommend it - is a different matter. And not that I would dare suggest such an illegal and unsafe installation, but still, it has worked fine for me. And that includes 1,000km destinations with treacherously steep descents, and I'm not known for being slow on rough roads, as well at typical peak hour and school traffic. Maybe I could ask why people are so keen on brake boosters or disk brakes, but I know the obvious and responsible response I'd get.
It's fine sticking to what works for you, however I'm curious where your beliefs differ.
lurch228 
Silver - Posts: 1,338
Silver spacespace
Joined: August 08, 2012
Posted: November 07, 2012 at 6:54 PM / IP Logged  
I not advocating doing anything that can be dangerous. I paralleled the batterys but not with out proper fuse protection at both ends, proper ground, battery tray, alt. upgrade to handle charging 2 batteries and the such.
I was asking about Hybrid battery chargers, not batteries. Like the Schumacher Hybrid battery chargers, like the SC-10030A SPEED CHARGE AMP HYBRID BATTERY CHARGER & TESTER that I have.
I have done construction from foundations, and concrete to roofs and everything in between. HVAC, automobile repair engine rebuilds. PC builds Repair, network setup and repair. OS repair (WINDOWS) virus removal Bios Modifing, minor electronics repair. AKA Jack of all trades master of none.
oldspark 
Gold - Posts: 4,913
Gold spacespace
Joined: November 03, 2008
Location: Australia
Posted: November 07, 2012 at 10:42 PM / IP Logged  
They call that "hybrid"! Down here we'd call then walkers. **
Hybrid chargers generally refer to those for hybrid vehicles though they could also refer to domestic "multi-battery type" chargers, and before then the good old "hybrid technology" markobabble.     
I don't recall much about the Schumachers, just be wary of the Optima 10A limit (and since good battery chargers have battery temp sensing - don't they?).
And check if it has a memory to return to whatever state after a power fail.
I use a similar but smaller (4A) 6V/12V pulse-charger that was $25 from Aldi. That's cheaper here than the old-tech voltage chargers, and less than 1/3rd the price of the cheapest equivalent "smart" charger. It doesn't have a memory, but I don't care at that price. It's just nice being able to forget about leaving a charger connected, as well as its other advantages.
You are aware that paralleled AGM batteries can be dangerous? Read up on AGM thermal runaway.
Also permanent parallel connection compromises battery life. In simple terms, the reliabilty with respect to self failure is halved for 2 batteries.
If one collapses, it will cause the other(s) to collapse. That's annoying enough with wet cells, but AGMs have their added hazard.
An whilst not so bad for 2 parallels, ie, if one fails you only replace 2, but for 3 it means replacing all 3 (& three times as often), etc.
In simple reliability terms (eg, using MTTF or MTBF type data), it means buying 4 batteries for 2 in parallel, 9 for 3 in parallel, 16 for 4, etc in the same time it would normally take a single battery to fail. [I hope I got that right. I once wrote so many paraphrased explanations and got so bored, and now I'm regurging my ancient wording without thinking. And it is exacting and it's easy to get confused.)      
It sounds like we have similar backgrounds though negligible construction work for me, and a wasted some time picking up a qualification along the way.
I'm definitely DIY, jack of many but maybe master else nee-master of a few, and definitely innovative with almost anything. (Hey man, I even invented recordable CDs LOL. Not quite in practice, but that's story I wrote hereon ages ago.)
** - PS: "waLkers" with an N is not considered an offensive term here, but it was auto-filtered by forum scrubber.
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