Big system, multiple batteries. wot do?

[Vagomire 10+ year member]

Hey I'm sure this has been posted a hundred times before but here's my question.

I have a small car with a 90amp stock alternater. I'm putting a 1700w RMS amplifier in it lol.

 

I have heard four different things.

 

1. Dual batteries must be the SAME battery otherwise voltage will be off and they fight each other.

2. Dual batteries have to be the same TYPE of battery (ex. Sealed Lead Acid).

3. It doesn't matter what size or type of battery either one is, one should be deep cycle though.

4. Just get one huge *** battery for the trunk and take the hood battery out.

 

I'm asking because I have a Duralast acid battery under the hood and I don't know how well two of those would work for such a big system.

 

Another question, just ground both batteries to the chassis or run a pos and neg wire between the two in addition to chassis ground?

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[mclerico83 5,000+ posts]

i have an isolator to seperate your front battery from your rear. sell it for 40 bucks shipped. than get one huge battery in the rear and it has to be sealed in the rear. this is how i would do it because it guarentees your front battery not getting screwed up and stranding you somewhere with only a 90 amp alt.

plus do the big 3 upgrade

Stinger S2402 240 Amp 3 Post Battery Isolator - S2402

 

[mclerico83 5,000+ posts]

sams club has duracell agm batteries for 99 bucks or o'reily's has them for 150. Also die hard plat at sears, they sometimes have great deals.

 

[SourDeez 10+ year member]

just get like 15 batteries bro

 

[itsblown 10+ year member]

Hey I'm sure this has been posted a hundred times before but here's my question.I have a small car with a 90amp stock alternater. I'm putting a 1700w RMS amplifier in it lol.

 

I have heard four different things.

 

1. Dual batteries must be the SAME battery otherwise voltage will be off and they fight each other.

2. Dual batteries have to be the same TYPE of battery (ex. Sealed Lead Acid).

3. It doesn't matter what size or type of battery either one is, one should be deep cycle though.

4. Just get one huge *** battery for the trunk and take the hood battery out.

 

I'm asking because I have a Duralast acid battery under the hood and I don't know how well two of those would work for such a big system.

 

Another question, just ground both batteries to the chassis or run a pos and neg wire between the two in addition to chassis ground?

who ever told you to get rid of the stock battery in the front is a retard.

who ever told you that you needed to have 2 exact matching batteries same company same brand or else one will pull voltage off the other is correct, that is if you dont have a battery isolator. With a battery isolater you can run 2 different kinds of batteries.

depending on how efficient your amp is however you may not need an extra battery. If you do install the system and have really bad voltage drop I would then price out the cost of these new batteries+ a possible isolator+ more power wire against the price of a new alternator. with an h/o alt you might not even touch the stock battery and ideally it would run almost completely off the alternator

 

[wickedwitt 10+ year member]

Do NOT take out your front battery. Change them both over to sealed AGM if possible. If not possible now, run AGM in the back and leave the stock battery until you can replace it. I've had a conventional batt up front with AGMs in back for more than five years now with no issues. That is not saying you won't have issues in the future if you do the same for an extended period of time.

 

[Vagomire 10+ year member]

So how do I wire in the battery isolator? Switch it off when I'm driving so that the car runs on the hood battery and the stereo runs off the trunk battery? Then turn it back on for a few minutes after I'm done playing to let the trunk battery charge back up?