Will 2nd battery put too much stress on stock alt

[PuZo 10+ year member]

I have an 80 amp alt and will be pushing 1250 rms. Main battery is optima yt second is powermaster d975 which i can possibly also fit under my hood. I was told adding the 2nd battery would put too much stress on my alt. My friend said divide watts by voltage to see how many amps you need to power it, so mine needs to be 87 amps. Would i be better off just using the 1 battery? Thanks

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[streetbeater07 10+ year member]

you'll be absolutely fine with both batteries.

 

[Johnny Law.Lulz 5,000+ posts]

A battery doesnt stress an alternator. If your al is pushing 80 amps then it should push 80 amps whether u have 1 battery or 500 batterys. Throw the second battery in for the hell of it.

 

[PuZo 10+ year member]

So meaning it would just take longer for it to charge the batteries

 

[kovemaster559 5,000+ posts]

just do the big 3 . should be good

 

[loudaccent 10+ year member]

having the mutiple batt are better so wen the bass is hitting its shocking the batts and not pulling stright from the alt..,

i run 1 batt on 6000 watts and i melted the alt, becuse there wasent enought reserve in the batt,,, you will be good

 

[kovemaster559 5,000+ posts]

AH and RC FTW

 

[scoob8000 10+ year member]

A battery doesn't stress your alternator (unless it's bad or dead).

I'd do the big 3 first and go from there. If it's still an issue, maybe a more powerful alternator before a second battery.

 

[PuZo 10+ year member]

Its either a 2nd battery or none, I cant afford a new alt right now

 

[BassAddictJ 5,000+ posts]

do the big 3. then add the second bat. no need for isolators or solenoids. itll take a lil longer for the bats to get fully charged than 1 bat, but as for daily driving you'll be fine. ive been doign extra bats off stock alty's for YEARS without issues. to reduce the amount of workt he alty has to do try to bump when your rpm's are at or above 2k. dont sit there and beat the hell out of your bats with the engine idle. but you'll be fine.

i ran 2,500w rms off 2 red tops and a 90amp alty for quite some time with no issues... you'll be A Okay with 80amps, 2 bats, and 1250w rms....

 

[PuZo 10+ year member]

If I dont use an isolator, then what will happen if I play music with the car off? Will it use up say half of the main and half of the other? Would it still be able to start?

 

[n2audio 5,000+ posts]

A battery doesnt stress an alternator. If your al is pushing 80 amps then it should push 80 amps whether u have 1 battery or 500 batterys. Throw the second battery in for the hell of it.

That's not true at all. While a healthy battery shouldn't require a lot of current it IS w/o question a load to the alt. I know it was just to make a point, but an excessive number of batteries - even healthy ones - would tax the average alternator severely.

having the mutiple batt are better so wen the bass is hitting its shocking the batts and not pulling stright from the alt..,

No - that's not how it works. Whether you have 1 or 10 batteries they are completely invisible to the electrical system up to the point that the alternator is maxed out. The alt is the highest potential in the system, so it is always the source until its current capacity is exceeded. Mult batts only lightens the load on the batts. They increase the load on the alt - maybe only minimally, but a minimal increase is still an increase.

i run 1 batt on 6000 watts and i melted the alt, becuse there wasent enought reserve in the batt,,, you will be good

You melted the alt because it was at 100% capacity every second. Like any electromechanical device - if you operate it at 100% capacity all the time -- it won't last long.

I'd do the big 3 first and go from there. If it's still an issue, maybe a more powerful alternator before a second battery.

Best suggestion yet.

PuZo - I was in about exactly the same situation as you with my old car. I had about 1100w and a 75A alt. I had a BIG battery - 900CCA IIRC. At idle I had right around 12v. At 2k 13.5v or so. Clearly the alt was under stress. It finally died after 2 yrs. I replaced it with a 110A and never saw less than 13.6v.

I'm not saying you NEED a new alt, but keep an eye on your voltage, and at the end of a loud listening session - especially if the RPM's are fairly low (local vs hwy) turn it down for a few minutes to make sure the battery gets a charge before you turn the engine off.

 

[PuZo 10+ year member]

PuZo - I was in about exactly the same situation as you with my old car. I had about 1100w and a 75A alt. I had a BIG battery - 900CCA IIRC. At idle I had right around 12v. At 2k 13.5v or so. Clearly the alt was under stress. It finally died after 2 yrs. I replaced it with a 110A and never saw less than 13.6v.

I'm not saying you NEED a new alt, but keep an eye on your voltage, and at the end of a loud listening session - especially if the RPM's are fairly low (local vs hwy) turn it down for a few minutes to make sure the battery gets a charge before you turn the engine off.

So I should maybe stay with 1 battery and then go from there? I think I can fit the battery in the front, so it wont cost alot to re-route some wires.

 

[n2audio 5,000+ posts]

You can go ahead and put it in if you want to.

If I were you I'd install the system first - see what you get - maybe take some voltage measurements at batt and amp under different circumstances, then put in the 2nd and do the same. See what/if any differences there are.

 

[PuZo 10+ year member]

Okay, last question for now, if I do manage to fit the 2nd battery in the front, do I will still need to fuse it twice?(the positive cable)