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2nd battery - ok to go direct to the alternator?

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drdx
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2nd battery - ok to go direct to the alternator?

Post by drdx » Thursday, 29 October 2015, 14:19 PM

Hello everyone. I've set up a 2nd battery on numerous vehicles in the past but I'm now challenged with hooking up a 2nd battery that is in the rear of my tiny jeep tj. I have high clearance fenders, a snorkel, and it is quite tight up by the battery. I'm installing it with a breaker or quick disconnect at both ends as I'm a safety guy. Can anyone think of any crazy electrical radio or car guy rules of auto electronics I would violate by connecting the 2nd battery directly to the alternator as opposed to the battery? In theory it would allow my 160 amp alternator to better direct feed the rear battery but I've had a few beers here on vacation and don't want to incur any weird issues by doing so. The battery is in the back for an amp deck and to also help with a warn 8274 winch on the front and both batteries are identical yellow top optimas. Thanks in advance, my new mobile is almost ready to be revealed.

-drdx
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Re: 2nd battery - ok to go direct to the alternator?

Post by jessejamesdallas » Thursday, 29 October 2015, 16:15 PM

When I had my 8-pill hooked up, I had just two alternators...Factory alt went to main battery as normal, but the second (200 amp) alternator went to my battery bank where my 8 pill and driver was hooked up to...worked just fine.

Later when I went to a 16 pill and 3 alternators tho, I had all three alternators connected together at a distribution block (bolt in a box) then one large wire running from the box to the battery bank, and another to the main battery...That also worked just fine.
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Re: 2nd battery - ok to go direct to the alternator?

Post by 543FtWorth » Thursday, 29 October 2015, 16:54 PM

Since you're adding an extra battery I'm assuming the amp is going to draw more than the alternator can support. If that were not the case I'd say connect it to the alternator.

What I see happening is the amp will draw current from your second battery then draw current from the battery in the stock location via the stock alternator charging cable. If you haven't upgraded it it's probably small gauge and maybe even fused. There will be more voltage drop that way. I'm glad you are fusing it at both batteries because many people overlook that. I even carry cable cutters in the door pocket for some extra insurance.

I'm in the same boat with power. The truck has 2 batteries under the hood stock and no room for a 320 Leece Neville. I just have a 205 amp stock replacement and built a battery box that holds 3 1000 cca group 31s in the bed. It still drops about a volt when I key.

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Re: 2nd battery - ok to go direct to the alternator?

Post by drdx » Thursday, 29 October 2015, 17:44 PM

Thanks for the input. The way I run it, my draw, at voice leaks, is right around the alternator's output. At deadkey I'll likely be at a quarter of that. I'm not sure why you'd need 3 alternators but understand liking the headroom. This is a mild setup where I'm only expecting 100w a pill max. I can wedge in a 2nd alternator but radio here is so dead that this setup may not be in there long as it is.

I guess give it a try to the alternator and watch the voltage.


-drdx
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Re: 2nd battery - ok to go direct to the alternator?

Post by 543FtWorth » Thursday, 29 October 2015, 18:52 PM

CB is dead here too except for the drunks (not classy drunks like me) agitators and dumbells that play into their game.

Shoot me a PM or text if you need a long distance radio check. I finally got some multi band wire in the air too.


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Re: 2nd battery - ok to go direct to the alternator?

Post by jessejamesdallas » Friday, 30 October 2015, 3:39 AM

drdx wrote:Thanks for the input. The way I run it, my draw, at voice leaks, is right around the alternator's output. At deadkey I'll likely be at a quarter of that. I'm not sure why you'd need 3 alternators but understand liking the headroom. This is a mild setup where I'm only expecting 100w a pill max. I can wedge in a 2nd alternator but radio here is so dead that this setup may not be in there long as it is.

I guess give it a try to the alternator and watch the voltage.


-drdx
set-up was going to be for a 32 pill originally is why I was going with 3 alt...Now tho I'm back down to just the factory alt, and a 2-pill...
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Re: 2nd battery - ok to go direct to the alternator?

Post by drdx » Friday, 30 October 2015, 5:05 AM

It is funny how I threw this out and the only responders were north tx *Censored*, lol. I'll likely end up with a simple 4 pill but since I own all this stuff already I figured I would put it all in and give it a try. Worst case scenario it is all hooked up and working which makes it easy to sell.

Jesse- I ALMOST took the 32 pill plunge but glad I didn't. At that point it is a dedicated radio machine. That would have been much more fun years ago. In all reality the signal difference just isn't worth it and a healthy 2-4 pill setup is hard to beat for simplicity and daily use unless you are still in the slugfest mode. I think I'll be the only slugger in my town and probably for those close to it.

Hey 543 I'll shout when I'm back home for another stretch and throw up a wire and we can hook up on a lower band. Work has me flying out in a few days once again.

-drdx
Yes it's me, Dollar-98, drdx, the original all *Censored*, shot cawla on workin this no-fade technology.

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Re: 2nd battery - ok to go direct to the alternator?

Post by MDYoungblood » Friday, 30 October 2015, 7:55 AM

I never needed 2 batteries to run electronics but my '83 CJ7 I did have several KC lights and a Warn 12K winch, used two on that, moved (because of engine swap) the original location battery to behind the rear seat with 0awg cable, never had a problem. swapped to a chevy 350 so a HP alternator was an easy swap, 250a@2000rpm and the engine always ran in that range because of the big gears.
My Dodge Ram has an isolator installed for the campers batteries (2 in it), to keep them charged while driving and shuts off when not, (keeps the starting battery from discharging). The Dodge has a 210a alternator from the factory.
Biggest mobile amp I've ever had was a 4 pill and my stock charging system always handled it.

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Re: 2nd battery - ok to go direct to the alternator?

Post by 543FtWorth » Friday, 30 October 2015, 16:43 PM

A 4 pill offers alot of bang for the buck. Most charging systems handle it fine. If you go to a 16 pill you gain an S unit but then you you have a 2 or 4 pill driver depending on how you run the stuff. It takes alot of current for that extra S unit.

I have a 16 in my daily driver but if I ever build a bigger mobile the final amp will have a tube or 2. More efficient so more watts and less alternators. 1 320 leece and a 3cx3000 is cheaper when compared to a stack of pill amps and all the equipment to power them.


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