# Multiple Alternators and Batteries



## GoodyearJ (May 4, 2011)

Does more alternator amperage lessen the need for multiple batteries? I currently have one 250amp alternator and two batteries. I'm planning on running a triple alternator setup. I don't do competitions and the only time I listen to my stereo is when I'm driving. I understand that the batteries just store reserve power. With well over 500amps @ idle will it be necessary to add more batteries?


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## Aaron'z 2.5RS/WRX (Oct 24, 2007)

for the love of ****ing god.... why... 

Why would you want or NEED 3 alts in a driver...??? 

You aren't even going to compete..??

Do you have ANY, I mean ANY, thoughts of being able to hear as an adult?

Wrong section, should be in the SPL section and hell, wrong FORUM, should be over on CA.com...


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## GoodyearJ (May 4, 2011)

Lmao. I'm already hard of hearing. Not from stereos, but from work. I used to be a musician, an engineer on a ship, and a mechanic. I don't listen to it that loud(to me) often, but when I do crank it I don't want any voltage drop. I'm planning out my next upgrades which will likely double my power output. If I can avoid spending hundreds on extra batteries that could possibly be stolen( drive a truck) I want to


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## Mr. Nice Guy (Jul 21, 2011)

How many watts RMS are you running in your amps?


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## GoodyearJ (May 4, 2011)

Mr. Nice Guy said:


> How many watts RMS are you running in your amps?


Over 3000 watts now. When I'm finished it will be right under 7000rms


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## Mr. Nice Guy (Jul 21, 2011)

GoodyearJ said:


> Over 3000 watts now. When I'm finished it will be right under 7000rms


You're fine for now, but 7kw would require around 500A. You'd probably be fine with 2-250A alts, but I like headroom for the 40A or so of car electronics, so if you can find a 300A to add to the 250A, that'd be even better. But you won't need 3 alts. And I'd say just a single good battery in the rear would be fine, aside from your battery under the hood.


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## GoodyearJ (May 4, 2011)

I currently have 2 under the hood. The reason I'm considering 3 alts is that I have 2 extras laying around. I found a guy that will make a triple bracket for less that most places charge for a dual kit without alts. I spend a lot of time sitting in my truck at idle also. I've also considered getting 2 batteries and mounting them on each side of the sub box inside the truck. I've been told you can do that with AGM's. Is that true? My thoughts for the electrical are the same as my system design, overbuild it. I may never use the 7000 watts, but to me its better to have 7k and not have to strain it that have 3500 and push the hell out of it


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## Mr. Nice Guy (Jul 21, 2011)

Headroom is nice if you've already got 3 alts to work with, so it certainly wouldn't hurt, other than just being one more thing that can break down. If I were in your shoes and I had 3 alts, and they were all 250+, I would just build a dual bracket and run two, and then have a replacement sitting in the garage, not getting wear and tear on it, and not sapping horsepower, in case one should quit, I could just swap it out with the spare. But 3 might be worth it if they could increase your idle amperage to make it possible to get a full 14.4V at idle with everything blasting. That would be an ideal setup for anyone, so if you've got the time and money to make it happen, do it. 

But make sure that the 3rd will be an improvement, make sure you look at how they're wired and wound to perform at idle, 1500, and 4k rpm, to make sure that they'll reach your goals. If all 3 are wired to only put out rated amperage at 4k+ rpm, you might still be stuck with 12.8V at idle with everything cranked up. And to build a 3 alt system only to get results like that, would be a tragedy.

Let us know how it goes.


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## GoodyearJ (May 4, 2011)

Will do. Thanks. Currently I only have one 250. The others are 135. I was going to use those until I saved up for 2 more 250's


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## Mr. Nice Guy (Jul 21, 2011)

GoodyearJ said:


> Will do. Thanks. Currently I only have one 250. The others are 135. I was going to use those until I saved up for 2 more 250's


That'll be just about perfect as far as total amperage needed for 7kw and some headroom for your car's stock electrical. What kind of car is it? I'm thinking about doing a dual alt setup down the road myself, always looking for ideas.


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## GoodyearJ (May 4, 2011)

Its a 2000 silverado with a 5.3


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## [email protected]&$ (Apr 10, 2021)

Mr. Nice Guy said:


> You're fine for now, but 7kw would require around 500A. You'd probably be fine with 2-250A alts, but I like headroom for the 40A or so of car electronics, so if you can find a 300A to add to the 250A, that'd be even better. But you won't need 3 alts. And I'd say just a single good battery in the rear would be fine, aside from your battery under the hood.


I know this is an old post but I’m curious about what happened with your setup I’m new to the stereo stuff but I’m running 3 alternators 3 batteries hopefully that’s enough power to run a 13k amp


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## dumdum (Feb 27, 2007)

[email protected]&$ said:


> I know this is an old post but I’m curious about what happened with your setup I’m new to the stereo stuff but I’m running 3 alternators 3 batteries hopefully that’s enough power to run a 13k amp


Just run three banks of 40ah lithium and a couple of alts (your three will be fine) and you’re fine for 13kw easy

if you just have 3 lead acid agm batterys you will struggle with keeping voltage solid... battery delete and lto will be a massive improvement 😉

the guy with 200 odd posts from 2013 likely didn’t hang around... I’d recommend making a new post 👍🏼


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