big 3 upgrade on integra, fuse box?

Hi, I had my HO alt and 0 gauge wiring done professionally and for some reason he claimed that he couldn't fit the stock wire so he took it out. The problem begins with the fact that the Integra wiring goes from alternator->fuse box->batt. positive. So what he did was wire the 0 gauge to the fuse box, and then left a stock wire going from the fuse box to the battery (which defeats the purpose of using 0 gauge). The way the fuse box is I'd have to tear it apart to fit another 0 gauge wire so that's not an option. Here is a picture of what I'm talking about:



I need to get 0 gauge all the way to the battery, and the fuse box kind of prevents me from doing this. Is it possible to just run straight from the alt. to the battery and then add a wire battery->fusebox, or must the alt. wire pass through this?

That does not look professionally done to me. I dont see an upgraded ground wire from the (-) battery post. I dont really understand what is all under the hood of your car, so im sorry I cant help. Heres some info about the Big 3. https://www.the12volt.com/installbay/forum_posts.asp~TID~73496~PN~1

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Well theres a reason for the ground, that was something Im doing myself. He was just doing the HO install and alternator wiring. I understand how the big 3 works, but most cars just go straight from alternator to the battery and dont have this fuse box ran in the middle.. And because he didn't leave the stock wiring in, I have to find a way to get 0 gauge all the way to the battery while getting this fuse box power.

As far as I am concerned, there is no need for an alternator to battery fuse, EXCEPT to protect the cable in case it rubs bare or comes loose (from the alternator end).

Older cars never had them. I suspect they figured the same safety/security as the starter-motor cable. (No fuse; make it heavy enough and physically protected enough etc.)

I sarcastically wondered is fuses were introduced in a vain attempt to prevent Bosch alternators from blowing.
Others may have introduced it to protect their alternator's power diodes in cases of reversed battery connections. (Yet my mate's 1966 23A alternator survived SEVERAL reverse hits from his fully charged and brand new incorrectly(!!) labeled battery terminals!)

My experience has been that reverse connections blow alternators with fuses, and does not blow alternators that do no have fuses.

As to protecting the cable or alternator from battery end shorts, alternators are supposed to be self limiting - their windings are normally designed for the magnetic saturation etc, and their diodes should be likewise rated.
But this morning I read of burning alternators due to bad batteries. Maybe a non-OEM alternator rewound for certain performance? Certainly HO alternators seem to have poor output at low RPM - I assume thicker but less windings for higher current capability. But what then of magnetic saturation etc?
Or are all your alternators that bad?


Anyhow, my experience is that fuses do NOT protect alternators.   

Hence I reckon you can skip the alternator to battery fuse.

And why have a fuse to the fusebox from the battery or alternator?   

And why involve the fusebox anyhow? Surely you have specific distribution to you higher power loads?

But remember too that a fat wire with a short thin bit is still much better.
It's not the same as a restrictive water pipe that DOES choke water flow. The "extra loss" is merely its higher resistance (per length) times its short length.
The bigger risk is fusing, but if short enough, it shouldn't fuse because the thicker 0G conduct its heat away quickly. (Remember, cable current ratings are based on a "free length" of cable...)
Likewise the 0G will keep the short smaller gauge cooler compared to a longer piece, hence lower resistance....


But as usual, decide what your target is.
Usually it's big amps in the back rather than the battery.
Normally the battery only requires enough cable to carry 2 Amps - it's only for cranking that the cable is upscaled, and to a lesser extent the discharge-replacing current (which usually isn't more than a few tens of Amps for long anyhow.)

But then you have the thumpers - whatever it is that draws peak current. And if the alternator can't supply that, you are looking at (say) a 1.5V drop or more as the battery takes over.... Plus whatever IR drops along the distribution path from whatever power sources exist.


But yeah - that is a strange "professional" job.   To go to the trouble of dropping resistance, only to add a resistance (the fuse) and more resistance (the longer loop of cable). And to actually create an insulation-chaffing in the process!

Professional used to mean quality.
These days it has been relegated to its literal "paid" meaning.
But I still prefer to crap my own pants for free. It might be just as warm, but it's cheaper and IMO doesn't stink as bad.

oldspark wrote:

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But I still prefer to crap my own pants for free. It might be just as warm, but it's cheaper and IMO doesn't stink as bad.

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LOL. Funny, but true.

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For Pete's sake Godd Dan It, I wish you'd stop brown nosing!

You know as well as I do that my crap smells far worse than yours.
And I'll admit, you may have a better class of sht than I.

Bottoms up.

Peter.


PS - Any puns accidental or otherwise are intended, even if they leave a bad taste in your mouth.... or any other post-recipient.

PPS - oooh those puns!
Now what was the OP's question?

Well although that's an interesting side of the discussion I bought the fuse because a lot of places seem to think it's extremely dangerous to not use one, and right or wrong I think I'd rather not take the chance -- it's not like fuses are expensive. About the loop, there really isn't much room under my hood, especially for something that big so I couldn't really think of a better way to actually mount it so that the hood has clearance to close but that was his doing.

Oh, and the stock wiring in this car actually went alternator->fuse->fusebox->batt. positive -- which is probably not the best setup but now I have to deal with it.

nstillmatic wrote:

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...a lot of places seem to think it's extremely dangerous to not use one

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They weren't per chance the same people that told kenwood_nut (for his 120V AC switch issue) "there MUST be a ground to the switch, and if there isn't, to make one"?    
(NOT to be confused with the couple that also told kenwood_nut "that there shouldn't be a ground to the switch"!)
Regulations aside, it seems yet again that the minority were correct.

And do those people really think, or just seem to think? I'd rather a place that knows!
But from a survey some years back, it seems very few do know. And usually not those that were adamant that they did know!


But the test is in the asking - "why the fuse?" - then you'll see....
Eg - if to protect the cable, fuse at the battery and, or alternator end, or both?
Or why isn't it dangerous for the starter-motor to have unfused +12V at its heavy terminal? (And that's probably further from the battery with a less flexible cable!) (XJ6 owners - quiet please!! HowieQuips however will be tolerated.)   


And I do find it amusing when supposed safety features cause a hazard, like (I suspect) your length of unfused 0G
to the left and above the 200A fuse. (Honestly, why is that fuse SO FAR from the battery? If it were mine, I would remove it and run a shorter and physically secure cable. It is currently a short waiting to happen! Else a short waiting to become current.)   

Incidentally, alternator to loads and then to battery was the preferred wiring. It was often done in pre-HID days for headlights.
And it should be common for hi-power audio setups - except perhaps where power ripple is a problem (noisy rectifiers; no other battery or cap closer to the amp else HU etc).

Those that use the "absolute ground" argument(s) should agree that alternator to loads makes more sense anyhow, except for those with bigger systems where the biggest concern is when the battery is the absolute ground.


The point being that the correct topology depends on your requirements and situation. (IE - alternator to load, or to battery. BIG audio systems usually take the alternator to the REAR or remote battery, and feed the main/front battery from the remote/rear battery.)

Apologies for repeating yet again.

Without stirring the crap, a) Fuse is much too far from the source, should be 4" (10cm) from its source.
b) 200amps. If you pull enough juice to blow that your engine block will melt. As an example, on the above vehicle the main ignition fuse (in that fusebox above) is rated at (only) 50amps.
Throw away the fuse and go directly to the battery.
Incidentally we all have a wrong impression here, I don't think it goes "through" the fuse box, I think they are joined but then I think may-be it was beyond the poster's capabilities to remove the cover.

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Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.

Okay, I made a few changes before I saw your last couple posts. This is what I have right now:



Alternator->200a fuse->batt. positive->fuse box

The fuse box is being powered and everything seems to work. So there is no reason to have that 200a fuse then? I'm going to be running a dual battery setup, do you not recommend to use fuses inbetween the 2 batteries either?

Assuming that you will be using a split charging system, it will have its own provision, but then Oldspark is the Guru on split charging systems.

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Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.

Well I was going to just wire batt positive to positive and then negative to negative with 0 gauge wire. I was told that there should be a fuse at least 12" away from each battery.

So

[battery 1] -> [fuse] <---------------> [fuse] <-[battery 2]

(Second battery would be in trunk). This is the way I was told to do it, and the negative just runs straight through. I'm asking because it seems like you guys don't necessarily agree with how fuses should be used.

Never more than 4" from the battery. The further away the worst case. Your info as against our experience doesn't count for much. The negative doesn't run through, it goes to a local GOOD ground. What no splitting circuit?

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Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.

Yet again I see all the perverted rules, or misunderstanding of particular rules in different conditions.


EG - batteries should (or shall) be fused.

Some of the caveats and exceptions:
Not if it is physically secure (eg telco bus bar DC supplies; car starter cables, or SHORT runs).
Short runs may not be "physically secure", but the chances of a short over that small distance (or melting wire hazard) are riskable.
Fuses shall (obviously) be as close to the power source (battery) as practical. Hence consideration given to mounting hardware etc. EG - better to have a secure cable to a remote mounted fusebox than riskier fittings on top of or closer to the battery.

nstillmatic wrote:

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I was told that there should be a fuse at least 12" away from each battery

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Why? Does that person suspect a gas risk? Aren't you using approved spark proof fuses & breakers?
I was once told to drain my carbies before leaving my vehicles for long periods. Why? So that they could make money cleaning the resulting corrosion out of the carby. (Else by well intentioned people to gullible or brainless to know otherwise.)
The only general rule I give to such advice is to only follow the advice given by the minority - never the majority. (Generally speaking that is!)

There is no "general" fuse rule with specific distance.
The general rule is "as close as possible" but "without being stupid".   
EG - IMO your 200A fuse does NOT meet that rule.

Your last pic probably shows a greater hazard because of that fuse.
Either remove it, else add insulation etc to prevent fraying.
But that length is IMO too long. A shorter smaller gauge probably has less resistance - definitely if run direct with no fuse.


Ignore what you were told about a second battery.
Yes - you have protection (fuses or breakers) at each end of the battery hot interconnection.

From there it depends on what you want.
If they are to be permanently connected in parallel, then you want matching batteries - ie, from the same batch and history with both batteries located together with matched +ve & -ve bridging connections and power taken from the +ve of one and the -ve of the other.
Deviate from that and the batteries become less matched.

But I never recommend parallel batteries unless in constant use.
Why - because if one fails, both do. Your paralleled 5-year life-rated batteries may last 5 years or more, but if one fails within a few months, they both fail. (IE - a battery comprising 2 matched "monoblocks" has twice the failure probability of the single monoblock. Except that in the parallel case, the bad battery will destroy the good battery. [Whereas in series, no damage if not being charged.] And dare I mention acid, heat and thermal runaway?)

Hence they should have a isolator.
I use the charge light to control plain relays.
If no charge light (circuit) is available, then voltage sensing isolators can be used.
But typical alternator charge-light circuits win hands-down as battery isolators, and are cheaper and infinitely scalable to boot (in general, you merely add an ordinary on-off relay of your choosing).

And as with advice, be wary of the hype & bullsh with the various "smart" battery isolators, charge splitters etc.
I just bagged a particular splitter's advertisement for being a pile of bullsh (subject to recall or penalties if shown here). See here (Reply #13) on mp3car if interested.


PS - I forgot to detail the fuse "not on top" explosion risk in case of gassing (hydrogen gas from any lead-acid battery - especially deprecated bateries; especially wet cells, but AGMs too).
But I'll omit that. I don't want to drag up the common hype about connecting the +ve terminal first (because that's where the hydrogen is) (sic).

Okay, this is what I'm getting from what you're saying:

- Get rid of 200a fuse, run alt straight to battery
- (Obviously) shorten the wiring distance wherever possible
- Don't use any fuses whatsoever for wiring 2 batteries (?)

I appreciate your indepth responses, but it can be hard to decipher exactly what you think I should be doing. So I should be wiring both batteries together straight through without any fuses? I read your post on mp3car, what type of "plain" relay are you suggesting? I was looking at this:

https://www.amazon.com/PAC-PAC200-Battery-Isolator-Relay/dp/B000CEBXRS

That was merely an option though, I read that it's not necessary to use a relay at all so I wasn't dead set on adding one yet (if you have any input on that).

Also, to howie: the reason why I said ground straight through is because the best ground is from the negative battery terminal; not all cars have a good ground resistance so the battery is generally a safer bet.

BTW, the 2 batteries that I will be wiring together are a yellowtop under the hood (as you can see) and a Kinetik HC2000 in the trunk. What is the best way to accomplish this?

I think both Howard and I suggested getting rid of that fuse.
The main reason is that - in YOUR CASE - it is a hazard.
Normally fuses are desirable, but I explained above when they are not needed or not preferred.
I addition to that, I argue that they are not required between the battery and the alternator (other than the normal "cable protection from the power source" reasons.


For your case, I am worried that you think I said to connect wire two batteries together WITHOUT fuses.
How do you get that idea if you are placing one battery in the trunk?
(Others please chime in if you too get that impression. Not that I have yet re-read my post.)


Also can you name any cars that do not have a good ground resistance? What examples and situations have you witnessed?


Yes - "plain relay" means heavy contacts (a switch) actuated by a solenoid. There is no other (complex) circuitry - no sensing, no delays, etc.

nstillmatic wrote:

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it can be hard to decipher exactly what you think I should be doing

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That is because you have not defined what your are trying to accomplish.
Until then, I can only give general answers to common situations.

My general advice is to keep the standard cranking battery under the hood.
Then a remote deep cycle or cranking battery (eg, in the boot) depending on what performance is desired.

Well this is for car audio and other minor electronics.

What I have right now is a high output alternator installed + Big 3 done w/ 0 gauge wiring. The alt is connected to a deepcycle yellowtop battery under the hood with a 200a fuse as you can see. After reading all of your responses, I will be taking out the fuse and cut down the length of any wire if possible.

The next step I'm planning on taking is installing a Kinetik HC2000 as an auxiliary battery in the trunk. I'll fuse both ends as close as possible to each positive terminal and then go with that PAC200 isolator in the middle I suppose. As for negative, I guess I'll just try to find the best spot I can find for ground around the trunk area.

Does that sound about right? My only question I have now is what size fuse should I put on each end? (Obviously my choice of 200a between the alt and batt+ was not correct)

I don't know if your choice of 200A between the battery and alternator was incorrect. I just reckon its fitment was incorrect.


As to inter-battery protection, the fuses are to protect the cable and isolator. EG - the PAC200 is 200A rated, hence a 200A fuse maximum. But if our cable is 150A, then 150A maximum.
If you only need 100A, then 100A will do.

I don't know whether the PAC200 is the right size - that depends on the drain at the remote end.
IE - the inter-battery link should handle the maximum (average) current demand PLUS the recharge current for the remote battery.


But yes, you are now getting the gist of it.... (Yay!)


Now, how do you intend to control the relay? (IE - the battery isolator.)

And maybe you prefer putting the yellow-top in the trunk and using an ordinary cranking battery for the engine - unless you have a reason for a yellow-top or AGM cranker, or money is no issue.

The cable I'm using is 250A maximum, so I'm thinking 200A at each end because of the isolator. I was going to control the relay with the 12v ignition wire, or do you have a better approach?

And I already had a yellowtop before I decided to do any of these electrical upgrades. It's not quite as big as I wanted to use for my auxiliary so I opted to leave it for the engine (even though it's a little unnecessary).

Also, just out of curiousity, if the max amperage of the wire exceeds whatever your alternator is able to put out do you even need any fuses? (Sorry if that's a dumb question)

Yes.
ok.
Yes.. It's not a dumb question, but like your first question, I have provided answers.

Have another read.
Or search.

Yes your comment is correct which is why I said GOOD ground. We have had some older cars where grounding remotely, i.e. driver kick panel, trunk (boot) area, didn't work because of lack of continuity from movement, corrosion etc. By good ground, with a fully charged battery, going to an existent mounting hole or bolt position with the bare metal* exposed you should be looking at 12.5 between that point and the battery +. If that's the case no ground(earth) return cable is required.
*I once looked at a C type Mercedes returned from the body shop, it wouldn't start and they were blaming the alarm. What actually happened is that they replaced the area in the trunk (boot) where the battery was mounted. I bared the metal and replaced the M8 grounding bolt. Job done.
I STILL can't see what on earth requires 200 amps. You are almost into military requirements! But they use APUs/generators.
You are looking at about 85 amps draw to start your car then up to 80amps with EVERYTHING, heaters blowers, AC, rear defog, headlights, windows, wash/wipe, horns etc. Add the values of ALL your fuses in both boxes as used when the engine is running. Bet you don't get over 80 amps. Oh and the sheer fun NOT of running 0 gauge through your car.

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Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.

Well I don't think Integras have charge lights, and I'm not sure where to find a "voltage-sensing" isolator.

Well I'm running approx. 2000 RMS setup with other random electronics. Using a calculator it says that a 1500RMS setup will use 125A max by itself at 12v. So I don't see how 200A is that ridiculous? A lot of these big car audio setups require more amperage than it's base car functions do.

wth do you think the square red icon showing a battery on your instrument panel is?
Where apart from some deserted airfield are you going to be able to use 1500Watts? Say goodbye to your eardrums and window glass as the fenders fall off of your car.

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Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.

Frankly it would have been a lot simpler to power your audio gear off of a deep cycle and charge it every so often, don't even connect it!

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Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.

So how do you know if you have an electrical fault?

But if you don't think you have one and you see no advantage to my suggestion(s), get a voltage sensing battery isolator. They are known as "smart" battery isolators, sensing isolators, and even battery isolators (though the PAC200 seems to be a plain relay). Enjoy their hype!


Thanks howie ll - you managed to get a design parameter. Well done!
So it's page #3 and we know we are talking about a 2kW RMS system. That's a 200A design by my general rules (ie, divide by 10V).
So at full power, say 200A plus recharge current plus current for the other "minor" electronics.


Incidentally, your starter motor probably consumes about 150A if it's a reduction type; otherwise it's probably 250A or more. But that is on its own unfused cable from the battery +12V. I mention that in case you want to compare cable sizes.

Just realised what a PAC unit is. I've installed them, you only need a 1.5mm (about 16 gauge US) between the two. It's simply charging the second battery. Personally I'd use the cars original battery in the front the one shown in the rear.

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Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.

My last post missed howie ll's 2 prior replies. I suspect our opposing electron spin causes delays.... Curse that Coriolis dude!


Keep in mind that when the vehicle is charging and the amp is running, the interconnect will be trying to provide the amp/load current plus whatever has been discharged from the battery.

FYI - My 38AH AGM has about 40A initial charge after cranking (140A for a few seconds) and drops to under 10A within one minute.
(And hence why I use self-resetting circuit breakers between my batteries).


PS - Am I correct - the PAC is simply a 200A continuous rated relay? (aka contactor etc.)
I'd assume a 1A or higher solenoid current which may be too much for some alternators.

Wait, what? You're saying I should wire the 2 batteries together using 16 gauge wire? with that PAC relay, or am I reading that incorrectly? But yeah, the stock battery died a while ago and I replaced it with that yellowtop as seen. The auxiliary battery I'm going to use was already purchased anyway.