Running 2 batteries?

Inprogress · Feb 17, 2008, 01:37 AM

I was recently talking to an old friend of mine who has been in the car audio/competition business for over 10+ years and he suggested that rather then just running one battery in the trunk, that I run both my mini battery and redtop. He said to leave all the factory connections with the mini battery and run the system with the redtop.

His only concern was whether the stock alternator could charge both batteries or not.

Has anyone done this? Is this is even recommended?

Thanks.

biggie5252 · Feb 17, 2008, 07:19 AM

Usually when you run two batteries they're identical. You should put an isolator between the two batteries also. You could run into a situation where the alternator is too small to charge both batteries at the same time, like if you had the stereo on for an extended amount of time with the engine off.

Are you running some high powered stereo or something to justify 2 batteries?

Inprogress · Feb 17, 2008, 11:05 AM

I usually don't play the system without the car on. I wouldnt say my system is that loud, around 1000 watts combined rms from 2 amps, I initially bought the redtop thinking I'd only run it in the trunk
and take out the mini battery, but my friend suggested otherwise. I just wanted opinions.

Jameson_IXMR · Feb 17, 2008, 11:41 AM

Thats redtop can more than power your system and the car. I would just remove the mini battery. If you wired the batteries in series you would get 28volts (bad) and in parrallell you get 14volts but they share a load, so they act as one big battery, It would be easier to drain beyond re-charging in that setup. Just stick with the simple solution.

Sinister_Kid_xX · Feb 17, 2008, 12:35 PM

The problem with running 2 batteries is like everybody has said.. charging them. But if you run a Red top and have a system and your battery goes back optima wont touch it since you have a system. I would just say run a yellow top if you can. How come you want to upgrade anyways?

Inprogress · Feb 17, 2008, 01:03 PM

Why do i want to Upgrade my battery? Just for peace of mind. I just didnt want the system to strain the electrical system. The redtop I got is one of the better ones, 800CCA and 1000CA and plus the yellow top is $100 more expensive.

I'll prolly just run one battery in the trunk.

Any know if its recommended to ground the trunk battery in the front of the car or any where in the trunk ok?

biggie5252 · Feb 17, 2008, 01:26 PM

In theory you should run a power and ground from the trunk to the front of the car using at least 4ga. wire, but you'd probably be fine either way. I would spend the money/time to run the wire to the front and connect them to the factory wiring under the hood.

Inprogress · Feb 17, 2008, 01:37 PM

Yeah, I mean I have 17 ft of 2gauge for power and 3 feet of 2 gauge for ground.

My friend was telling me how there's less resistance in the front of the car or something like that.

While I understand I will connect the power to the factory wiring under the hood, how would this be beneficial to the ground?

Thanks for all the help!

Jameson_IXMR · Feb 17, 2008, 02:22 PM

If possible, (I would do it) ground it back up front to that lug that the stock battery/location goes to. There isnt less resistance up front, but more things are grounded up front, so it makes sense to have the ground point in the front.

Inprogress · Feb 17, 2008, 03:54 PM

Sounds good, but man is 2 gauge wire expensive lol

And wouldnt grounding it the chassis directly up front be better then connecting it to the factory ground terminal?

How many feet do you think I'll need? 15 I assume.

Inprogress · Feb 18, 2008, 12:47 AM

Anyone have any suggestions as to how many feet i'll need to run the ground to the front of the car?

Jameson_IXMR · Feb 18, 2008, 02:18 AM

Took me about 33 feet of 4ga to get to my amp behind the back seat. so thats like 16.5 power and 16.5 ground.

Inprogress · Feb 18, 2008, 08:43 AM

damn that's going to be expensive lol

ohio-evo · Feb 18, 2008, 08:50 AM

4 ga is fine for a charge wire to the trunk. I have ran 2 batteries in my cars for years. I would recommend getting a solenoid from stinger. This links the two batteries together when the key is in th eon position. You do not have to run the same type of batteries. I run the stock batt in front and a stinger dry cell in the back. And to answer the question if the alt can handle the charging the answer is yes. This also cuts down on the dimming of lights when listening at high volumes. although it does not completely eliminate it. i hope this information is helpful.

Inprogress · Feb 18, 2008, 08:58 AM

I'd really like to only run one as I'd like to make up for some of my expenses by selling my mini-battery kit.

I was told that if I run 2 gauge power, then my ground should be the same size, 2 gauge. Is this not true? I think I'd still like to run 2 gauge, but just am not sure if I'll be running it all the way to the front of the car. It is about 3.xx per foot of 2 gauge, plus shipping.