I gotta couple of Noob questions...

[CSCStang]

^^^Never had any issues with that, but a valid point nonetheless.

 

[FadedSpy 10+ year member]

that deka 9a34 seems pretty legit. states 120 amp hours of reserve. by rule of my thumb i choose amp hours as basic x10 = watts theory.
that single battery with 120 amp hours of reserve = 1200 watts of stereo power

two of them = 2400 watts of stereo power

also dont forget your front under hood battery also has amp hours of reserve altho i doubt its more than 50 or 60

and thats just my general rule of thumb to be on the safe side. i was talking with jim / mylows10 about how alternator power and battery power come together in our car audio needs as most guys will say get a high out put alternator and then you wont need a bunch of extra batterys exetra bla bla...

but im realizing that you do infact still need battery reserve power - even with high out put alternator because thats just how it works the best. when charging batterys the alt is at 14.4 volts - the batterys are all on what i believe is called "float charge" and will hold 13.75 ish volts... so when you play your stereo and the amps start bringing voltage down - the batterys actually start infuzing the electrical circut at 13.75 volts - even tho battery resting voltage is generaly 12.9 ish with the car engine off for an extended amount of time.

bottom line is it takes it to make it. to make full power at your amps you need battery reserve capable of withstanding your draw - and you need to have an alternator capable of keeping up with the demand of charging your batterys and feeding the amp.

Very useful information! I've been talking with Jim myself about all sorts of issues, he's got a wealth of knowledge for sure.

So, If I'm understanding you correctly, I should get 2 batteries that are 120-130 Amp hours each for my 2500 watt system and a 240 amp HO Alternator? Should I be concerned about 12V vs 14V or 16V? From what I've read there are Alternators that charge at different volts. Seems like more would be better IMO? Find 2 130 Amp 16V Batteries and a HO Alt that charges at 16V? Or is this overkill in my situation? After all, I'ts only got 2 subs in it...I'm not going to be competing, just a daily driver

 

[brian84corvette 10+ year member]

Very useful information! I've been talking with Jim myself about all sorts of issues, he's got a wealth of knowledge for sure.
So, If I'm understanding you correctly, I should get 2 batteries that are 120-130 Amp hours each for my 2500 watt system and a 240 amp HO Alternator? Should I be concerned about 12V vs 14V or 16V? From what I've read there are Alternators that charge at different volts. Seems like more would be better IMO? Find 2 130 Amp 16V Batteries and a HO Alt that charges at 16V? Or is this overkill in my situation? After all, I'ts only got 2 subs in it...I'm not going to be competing, just a daily driver

if you wanted to get in your car - and play your system above 80% total volume capacity for hours on end - 7 days a week - then that setup you stated would be perfect. most car audio dudes are running their systems on less than that because we are cheap bastards lol.

but yes - your above posted - 2 batterys and a high output alternator is ideal for your needs.

edit

you should look in to an internaly regulated alternator - its set to charge at 14.4 when its hot it may charge slightly lower at 14.2 or so and when you first start the car on a cold morning it might be 15.0 for a few minutes before coming back down to 14.4 no worries tho - thats still safe for car electronics... anything above 15.5 for an extended amount of time ( more than 10/15 minutes ) and i would be cautious