CCA vs Amp hours for Application

[mylows10 5,000+ posts]

ok i see, but if your cars battery is tied into the rear bank why would it count? just curious

It does. But for the car not the system

 

[bgowdy 5,000+ posts]

It does. But for the car not the system

ok i see

 

[TaylorFade 10+ year member]

Cranking amps are a good spec to use because it's directly related to the internal resistance of the battery and is an indicator of the discharge rate. The problem with cranking amps is that it's spec'd to a VERY low voltage. Too low for us (7.2v). But it's still a good reference since it's standardized. CCA (*cold* cranking amps) is how many amps a batt can provide for 30 seconds without dropping below 7.2v at 0*F. Cranking amps is the same thing but at 32*F (hence why it's higher).

Amp hours are indicative of very small draws for a very long period of time. And down to 10.5v. Very small draws for a very long time as in... 5A for 20 hours = 100Ah. And it's really more an indication of size than anything.

A little more relevant spec is RC (reserve capacity). That's how long a battery can sustain a 25A draw down to 10.5v. This is usually in minutes. Usually around 200 minutes for a good G31.

More smaller batteries are usually better in car audio applications than fewer larger ones. You get more contact area and cumulative CA for the same Ah.

 

[bgowdy 5,000+ posts]

Cranking amps are a good spec to use because it's directly related to the internal resistance of the battery and is an indicator of the discharge rate. The problem with cranking amps is that it's spec'd to a VERY low voltage. Too low for us (7.2v). But it's still a good reference since it's standardized. CCA (*cold* cranking amps) is how many amps a batt can provide for 30 seconds without dropping below 7.2v at 0*F. Cranking amps is the same thing but at 32*F (hence why it's higher).
Amp hours are indicative of very small draws for a very long period of time. And down to 10.5v. Very small draws for a very long time as in... 5A for 20 hours = 100Ah. And it's really more an indication of size than anything.

A little more relevant spec is RC (reserve capacity). That's how long a battery can sustain a 25A draw down to 10.5v. This is usually in minutes. Usually around 200 minutes for a good G31.

More smaller batteries are usually better in car audio applications than fewer larger ones. You get more contact area and cumulative CA for the same Ah.

i see... i think im starting to kind of understand some now. depending on my next vehicle space could come into play. i like the idea of those smaller batteries though, im about to sale me group31 to help save on some space, i have smaller group27 that i may end up keeping, but idk...

i also like the idea of all my batteries being the same brand lol, it would look better

 

[keep_hope_alive Premium Member]

I don't add batteries for systems anymore. i've found a much better solution.

 

[Jeffdachef 5,000+ posts]

I don't add batteries for systems anymore. i've found a much better solution.

ultra capacitor bank?

 

[keep_hope_alive Premium Member]

ultra capacitor bank?

yep. stock electrical, no more than 0.1V drop on music with car at idle.

extra batteries are needed for setups designed to play with the car off.