Why won't my battery charge?

[str8stang036]

Ever since I was able to start my car, the battery has never kept a charge. I have to constantly be charging it, luckily its a drag only car. But I am only able to get a few cranks out of it before its unable to work anymore. The alternator has been checked out and is ok, somehow it doesn't charge it. I do have underdrive pullies, but I am not sure that is completely the problem. My battery is in the trunk.

 

[rrl]

take the battery out and take it where they sell batteries and ask them to do a load test on it,and see if its ok.

 

[str8stang036]

I am going to check it tomorrow. Any other ideas besides that?

 

[cbarr300]

take a DMM and test the voltage coming out the heavy wire on the back of the alternator. Anything ~13.6-14.6 is acceptable.

after that take a reading across the battery terminals. It should be almost exactly the same as your last reading. If there was any difference then you have a voltage drop somewhere in your wiring.

If the alternator is putting out proper voltage, there's a good chance the battery can't hold a charge.

If you search for "alternator"...you're sure to find a good write-up by hissin50 (JT) about checking the alternator out.

 

[rrl]

since the battery is in the back make sure you check the cables thoroughly to see if they're frayed or have bare spots hitting against the frame etc.make sure connections are tight.

 

[juiced_94gt]

I just had a VERY similas issue...if your bracket is powdercoated you need to grind off the powdercoat where the alt. mates to the bracket, I went one step further and took the bracket off and grinded behind it where it mounts to the heads and block and my car worek like a charm afterwards... took four months but it worked if not HISSIN will give you a world of info, i wish I could buy him a beer.

 

[str8stang036]

I just had a VERY similas issue...if your bracket is powdercoated you need to grind off the powdercoat where the alt. mates to the bracket, I went one step further and took the bracket off and grinded behind it where it mounts to the heads and block and my car worek like a charm afterwards... took four months but it worked if not HISSIN will give you a world of info, i wish I could buy him a beer.

gotta check that also, the back of the alternator is black and front is polished. Maybe the paint is interfering with grounding.

How many grounds should be on the block?

 

[juiced_94gt]

gotta check that also, the back of the alternator is black and front is polished. Maybe the paint is interfering with grounding.

How many grounds should be on the block?

One on the chassis to engine on the driver's side and also one on the driver's side the the side of the timing cover

 

[earleys94gt]

+1 on checking the cables and connections between the battery and the engine compartment.

Did you ever get the battery load tested?

I had a similar issue with mine, but turned out my alt. was toast...Good luck.

 

[str8stang036]

Haven't been able to get it tested yet.

 

[rrl]

i forgot to ask you if you have a one wire alternator since its a race car.if it is you need to rev the car anywhere from 1400 to 3000 rpm's to kick start it on before it charges the battery.to see of it a one wire it'll only have one wire coming off the back.

 

[str8stang036]

i forgot to ask you if you have a one wire alternator since its a race car.if it is you need to rev the car anywhere from 1400 to 3000 rpm's to kick start it on before it charges the battery.to see of it a one wire it'll only have one wire coming off the back.

you mean besides the connectors? If so, there is only one 4ga wire going to the alternator.

 

[rrl]

if the big red wire 4g,is the only one hooked up on it then you have a one wire alternator.for it to start charging you have to rev the engine to about 3000 rpm and then it kicks on to start charging.if you don't rev the motor it won't kick on therfore it won't charge the battery.once you rev it and it kicks on you can let it idle and it'll be charging.you have to do this procedure all the time when you start it up.

 

[str8stang036]

Interesting, didn't know that. Once I check the battery then I will look into revving it over 3k. Thanks