How Many Batteries Do I Need?

[adjetta 10+ year member]

I have an 02 Infiniti I35 With a Mechman 270 Amp alt, and stinger Pro 1/0 for the big three, and charge cable. my current battery setup consist of 1 Diehard advanced gold agm in the FRONT: (775 CCA, 55AH)

and 1 Diehard platinum agm in the Back: (930 CCA, 75 AH)

My Setup Consist of 1 Sundown ZV4 18" Powered by 2 aq 2200's @ 2 ohms (4400 Watts rms @ 2 Ohms

and an Infinity Kappa 5 powering 2 sets of Infinity Kappa 6.09cs, and Hifonics triton on the 5th channel so (400-500 watts Rms @ 2 ohms)

In total im looking at 4800-5000 rms on a 270 amp alt, so I assume I will need a few batteries to pick up the slack, how many ah and cca do i need in total to keep my voltage solid?

P.S. Nothing is installed yet, and I'm still ordering stuff, so don't worry I'm not risking my gear on my poopy voltage

Click to read more...

 

[bbeljefe]

You need ~55AH of battery for each 1kW of power. For 5kW, that's 275AH and it doesn't matter if you use 275-1AH batteries or one 275AH battery. And since you're short of alternator, I'd bump battery capacity up to 300+AH.

 

[adjetta 10+ year member]

You need ~55AH of battery for each 1kW of power. For 5kW, that's 275AH and it doesn't matter if you use 275-1AH batteries or one 275AH battery. And since you're short of alternator, I'd bump battery capacity up to 300+AH.

what exactly do you mean by " short of alternator"

Assuming the alt will do about 180a @ idle and 220-240a at 1800 rpm, will this be adequate charge to keep 300 ah charged and happy while under a decent load?

 

[dbeez 5,000+ posts]

I usually do 1 group 31 agm per 1k as long as room isnt an issue

 

[bbeljefe]

what exactly do you mean by " short of alternator"
Assuming the alt will do about 180a @ idle and 220-240a at 1800 rpm, will this be adequate charge to keep 300 ah charged and happy while under a decent load?

You should have about 70 amps of alternator current for every 1kW of amp you're running, so you're a bit short. But yeah, you'll be okay so long as you have a bit of overkill on your battery supply.

 

[Side Show 10+ year member]

also it's not recommended to run different model/brands of batterys.... so get yourself 2 or 3 nice big batts (all the same) , two in the boot and one under the bonnet.

 

[bbeljefe]

also it's not recommended to run different model/brands of batterys.... so get yourself 2 or 3 nice big batts (all the same) , two in the boot and one under the bonnet.

Not recommended by whom? And more importantly, on what basis?

 

[Side Show 10+ year member]

not recommended by me, from previous issues caused by batterys not being the exact same. have also seen issues with 2 of the exact same batts of different ages always causes the older batt to die/give up

 

[Side Show 10+ year member]

I've got 2x orbital batts that when tested shows 13.4 v, but soon as you try to draw a decent load from it, it drops down to about 6v. I cant actually rmember the technical side of why it shouldn't be done sorry.

som1 more educated in batts may be able to chime in

 

[bbeljefe]

not recommended by me, from previous issues caused by batterys not being the exact same. have also seen issues with 2 of the exact same batts of different ages always causes the older batt to die/give up

On what do you base that conclusion? Correlation or some objective testing you've done that has yielded the same result over and over?

 

[Side Show 10+ year member]

multiple car's running duel batts setups, new batts not cover'd under warrenty once wired with any other batt unless both batts are brand new of the time of installation.

 

[Side Show 10+ year member]

does this sound right to anyone? or was the battery joint just not wanting to send us a replacement. (costs them almost the same in freight to send it to me as it does to buy the batts)

I would love to no the technical explanation tho

 

[bbeljefe]

does this sound right to anyone? or was the battery joint just not wanting to send us a replacement. (costs them almost the same in freight to send it to me as it does to buy the batts)
I would love to no the technical explanation tho

Well, the warranty situation is due to the fact that the manufacturer has no way of knowing the condition of other batteries that may be connected to the new batteries they are selling. But that has nothing to do with electricity and everything to do with business sense. For instance, a lot of salvage yards won't warranty a used transmission unless you put a new converter in it. But that doesn't mean that using two different brands of type atf transmission fluid will damage the transmission. It means the company that's offering the warranty wants to ensure that its risk is minimized.

As for the technical explanation, I offered that earlier on in this thread but... I'm always open to arguments against mine, which is why I asked your methodology.

 

[Side Show 10+ year member]

fair enough bud.......I did have it explained to me but at the time but it all went straight over my head. there is a reason, has to be coz I cant remember seeing a decent system with mismatched batts.....even all the big spl rigs, all run multiples of the same battery.

 

[dbeez 5,000+ posts]

Only issues I have came across has been mixing battery types as long as all batts in the bank are of same type ie (agm ) or other your fine your battery bank is only as good as your weakest battery as it will pull the others down.