Please help with a couple of questions

[502CEC 10+ year member]

I am installing 2 Hifonics BRZ2400's and a American Bass fl1404. I have ordered a 275amp alt.(peaks @310) from Ohio Gen. The questions are about batteries, 1. Are extra batteries used mainly for when the car is off? I had planned on just buying 2 yellow top Optimas and putting back there (would that be sufficient?), however after buying everything else $ is getting low. So question 2. Would I be ok with just 1 for a couple of weeks or do I need to go ahead and squeeze out the $179 for the 2nd one.Thanks to all that reply

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[Bitterclown 10+ year member]

From what I know which is not a whole lot is the extra battery is to hold you around a voltage of about 13v or something close to that. I know there will be a senior member that will correct me but to my knowledge the extra battery is just to hold more power for when your amp really starts demanding power. I would get the battery but if you cant at the moment I am sure you can tone your amp down so it doesn't demand so much power since it would put a lot of strain on your alt. You can take my advice how you want, but I am new to car audio and am still learning but that is what my basic knowledge of a second battery is.

 

[disturbed471985 5,000+ posts]

U will be fine with just 1 yellow top and a 275a alt of course a second would not hurt but it is something you could add down the rd. Does it do 275amps @ 3100rpms?? What does it do at idle 1000rpms??

 

[tpmeredith 10+ year member]

I am installing 2 Hifonics BRZ2400's and a American Bass fl1404. I have ordered a 275amp alt.(peaks @310) from Ohio Gen. The questions are about batteries, 1. Are extra batteries used mainly for when the car is off? I had planned on just buying 2 yellow top Optimas and putting back there (would that be sufficient?), however after buying everything else $ is getting low. So question 2. Would I be ok with just 1 for a couple of weeks or do I need to go ahead and squeeze out the $179 for the 2nd one.Thanks to all that reply

We've had a couple of debates on this exact question recently in the forum, personally if you're trying to run that much power you're gonna need at LEAST a 2nd one, hell even 2 in the back with that much power would be good. There's multiple reasons, even with 1/0 wire running to the back you're still gonna get a decent bit of resistance off two 2400 watt amps trying to draw power across at 10-15' cable vs a 2-3' cable.

Batteries are gonna make big bass hits / drops not impact your overall voltage as much and give the alternator extra time (Even if it's just half a second) to react and start charging again, with the result being less power loss

Personally I'm running 2500 watts on a 135amp alt and 2 batteries (~80ah in the front, 105ah in the back), I will say if I was gonna push anymore power I'd definitely need to upgrade the alt, but to give you a picture, before dropping my 2nd battery in the back I had heavy dimming with my voltage dropping to ~12v, obviously not good. Dropped my battery in there with the expectation of upgrading my alternator soon after, and discovered I didn't even need to up the alt as now it typically doesn't drop below 14v.

I'd definitely squeeze out the extra cash, however if you want to save some money order a battery from Bad4Health (can PM him, he's on this forum), I cant remember but I'm pretty sure he was selling them for $120 (remanufactured I think?) Good batteries though, I ordered one from him and it's running in my trunk right now.

That and if you're running that much power it'd probably be a good idea to run 2 runs to the back (2 hot and 2 ground) of 1/0 or higher instead of 1 run.