power wire size and fuze?

You should out that batteries as close as possible to the amp(s) - they should really be in place of the cap. Having long transmission between the batts & amps can compromise the AGM's low resistance (which is why they usually recommend AGM - aside from "internally housed" legalities & considerations). Optima Jim from Optima reckons "you can parallel Optima batteries" (ie, yellow tops) - mind you, he didn't think it effected their reliability! & LOL! I agree that you can parallel (any) batteries, BUT, if you want them to last..... But you can search my posts for that. (I presume you'd want to run the standard cranking battery up front and 2 yellows (or beer batteries) in the rear. Hence you probably just need one small-standard relay ($3?) plus two ~400A or 500A relays ($20-$30?) for automatic isolation. Then the normal fuses or breakers at each interconnection end etc.)

For 2/0 cable you might try welding cable. It won't be as flexible as high strand count, but it should work. The insulation is generally really good and strong since it is designed to be used in a work environment.

I don't know how you would wire in the cap given what you are doing. If it were me and I was going to use a 2 amp set up I would probably use 2 caps. I would run one on each line for the sub amps and put them in after the distro block. again, I have never used caps so I don't know the ins and outs or what things you have to watch for.

For ground, you just want to match grounds with power wire. Electricity makes a loop which means what travels through the power wire has to travel through the ground so ground should be the same size as power.

James

ok thanks guys. old spark: i have been reading that i would be better off putting the batteries under the hood cause they charge better in the heat? but i agree with you that i would like to put them in the back with the amps. but i dont know how/where to wire in the relays. can u give me a page or vid to look at?

What the heck have you been reading? Put them in a fire - they'll have even greater capacity - you don't even have to charge them! Heat destroys batteries! (As with most things.) What's the rule = half the life for ever 10 or 15 degree C (~18F - 27F) increase? And why is "better charging" so important (not that I am saying heat means "better" charging)? What is wrong with normal charging? Finally, since you have the extra cable (incl ground) resistance from the hood to the trunk/boot, how does that compare to the resistance gain of using AGMs in the first place? Why bother even using AGMs - wet cell will handle the hood heat much better than AGMs, and probably cost well under half as much, and probably with negligible audio performance loss (as I said - what is the extra cable resistance?).

i read that having batteries in ur trunk at a much lower temp than under the hood will cause there rate of recharge to be slower. i read that on car audio magazines website. and the reason i will use dry cells is cause they can handle drain and recharge something like 8 times better than wet cells. so i have also read. and they have lower internal resistance which allows for a faster charge and discharge rate.not to mention they can be mounted any way to fit better and they are not likely to be affected by vibration.

rady449 wrote: i read that on car audio magazines website

So they are suable for misleading information.... I suspect they are into money generation and supporting their industry. Else the contributors think they know it all (like the "the voltage is 14.4V BEFORE it passes thru the voltage regulator, thereafter it is 13.8V"... sorry dude, a car's voltage supply does NOT pass thru a voltage regulator! And it is often above 13.8 etc...) Read elsewhere. Heat generally increases the resistance of things so why heat up a battery? Rate of recharge slows with temp? Why is recharge a concern - when would you need to recharge them that quick? And if a battery is hot, don't you have to slow the recharge rate? Optima specify 50C/125F as one of their recharge temp limits... EIGHT times better? How? Usually AGMs are only HALF the resistance or flooded cells. (Maybe they quote 10 year old flat batteries???) And they are saying you can pump a higher current into an AGM? An AGM has no liquid to boil off to keep cool. I think you will find "quick charged" wet cells last far longer than AGMs! How are wet cells effected by vibration? Mine vibrate all the time! Not to mention my 4-wheel jumps etc. But yes, internal "non-vented" mountings and any angle (except upsidedown for some) is a reason AGMs are chosen - but that should be irrelevant in a engine bay. Maybe you could check some of those details at batteryfaq.org or one of its references/links. I'll let you decide what you want to trust. I've seen enough audio forums recommend batteries rather than a properly sized alternator or that lower-ohmage speakers are better to last me a while. Many still spruik capacitors (despite the guy that pioneered caps subsequently condemn their use!). And recently I've seen gems like "100AH per 1,000W" for battery sizing!    It's Frank Zappa's Flakes all over again! (Gotta love a free but expensive market eh?)

u know u are probably right, thats y i made an account here and started asking, cause i have been i love with quality car audio fr like 8 years now but only in the last year have i really started to reserch the facts about how to produce it cause the crap the local stores feed me has repetedly failed. and thank you for the link:) what do u think about putting one large batteri in the back, like 200amp per hour discharge. or would that really only be for playing without running the vehicle.

Firstly, I asked an "audio" guy where I work if he had ever heard of anything (so ridiculous....). Once thru a common usual rap of "there ain't dry cells - only gels" (wrong!!), he greed crap, heat is bad etc. He added how he only had one (extra; dry-cell) battery in the boot. Also that if your 2nd bateries die, that's because they are powering jackhammers which are this high & .... (Sound comps etc.) So hence secondly, battery sizing depends on the peak thump etc. (Oddly enough he said drys/AGMs handle it all - despite the jackhammer failures - but the point is that flooded cells have double the impedance therefore limiting their current and therefore they usually do withstand such hammering!) It's a case of overall design. Is the alternator big enough to handle the load? If it handles full load RMS, then you probably won't need batteries because the double (and higher) peak output of an alternator is equivalent to having a battery or cap. If sound dips are due to high current/resistance from the alternator (& main battery) to the rear mounted amp, then a battery is mounted next to the amp. (Else a cap if you can't afford a $20 AGM!) If undersized alternators are the issue - meaning that your batteries discharge during audio use - then battery size depends on how long for and what magnitude - ie, AH rating. (The same as for "reserve time" - playing time without charging.) Remember that the LESSER current a battery is discharged at, the LESS the discharge amount (depth), the SLOWER is is recharged (ie, longer with less current) and the LESS OFTEN it is recharged, the longer it will last. BTW - batteries HALVE their life for every 10C/18F increase, so under the hood, you might replace your yellow tops 4 times as often as being mounted in the trunk; maybe 8 or 16 times as often as being vented from the cabin.     Thanks for the compliments... The problem with audio forums is that many use an isolated i of data or fact without appreciating the overall picture. EG - instead of mounting in the engine bay, spend 25% extra on capacity and save $300 on ongoing expenses! And as I said, what about the increased voltage dip due to the remote battery, or increased resistance from temperature? (They do know that quoted battery resistances are ONLY for fully charged batteries? Resistance increases as they discharge.) And no mention of voltage compensation for said temperature changes....

ok so what would u say about this....i wanna add a 250 amp alt. and connect 2, 1/0 power wires to go to individual optima yellow tops, then through there own 10 farad cap and then to the 180 amp 2000 watt amps. all grounded to the same point. and the component amp i was going to connect on the cranking amp under the hood that will still be charged off the stock 130 amp alt. also grounding the amp to the same point