Hello everyone,
I have a simple question about which battery to use:

I have a 347 stroker engine w/ a 100amp alternator. I've gone through 2 batteries in the last 3 months! They can't be jumped or even charged at the autoparts shop. Luckily the warranty replaced the second one for me. I drive this car at least weekly.

Any ideas what is going on? I bought a Interstate Gold battery with higher crank power today(I think its 610 amps).
What batteries are you all using and any advice on which would be best with this engine?
Thanks for any help!

 

Your problem is likely the alternator or voltage regulator. Essentially, you batteries are being cooked.

Get your alternator/regulator tested.

Your battery does not care what starter motor it is supplying with amps. Any battery the store sells will work fine.

I use a little Batt battery. It is half the size of a regular battery and half the weight. I built a little box for it to sit on the inner fender. You can hardly see it.

 

What type of 100A alt. do you have? one with a built in regulator or the mid 70's Ford large case 1G alt. with the external regulator? If it's an internal regulator one it's easy to get tested as one piece, I'd take it off the car and take it in to be tested. If you have the separate VR I'd have that alt. tested also and replace the VR. I agree with Bradley, you are cooking your batteries (over charging them). The cells smell like spoiled eggs when this happens usually and the sides bulge out. Any normal battery should work in your car, threre is a reason you're going through them.

Are you sure all the wiring is correct to the alt. and from the VR?

Jon

 

Your new battery choice is fine. What you don't say is how the other two batteries failed. If they boiled out the electrolyte or had high water usage, the poster suggesting overcharge may be correct. On the other-hand if they just failed to hold a charge, they may have both had mfrg defects or you have a pretty nasty short in your. car. The correct thing to do is to perform a starting and charging system test. Most autoparts store have th etools or your local sears or pep boys can do it for you if you don't have a VOM or DMM. Starting test - have someone crank the engine with the coil wire disconnected and look for no less than 9.8 - 10 volts across the battery trminal. charging test- with VOM or DMM across the Batt terminals start the car and the voltage at about 2000 rpm should be no less than 13.5 Vdc (fully charged battery) to 14.5 Vdc. pull the headlights on if below 14.0 to make sure the voltage increases. If more than 14.5 you have a Voltage regulation issue.

 

It's HIGHLY unlikely that 2 new batteries would fail back to back that close together.

Something is wrong...bad alt, bad ground, voltage regulator.....something.

 

thanks for the help guys, i took it to a trustworthy mechanic and he said the alternator was ~12.5, so i got it replaced. hopefully this is it!

 

what is it now. i guess they checked after replacing? what is it at idle and where (voltage) does it peak when you rev it?