battery not charging

[kr8zstang]

o.k. i got my battery charged and the car starts fine and runs fine, but i don't think the alternator is charging the battery. at idle, the voltage started at 11.95 and dropped to 11.85 in 5 minutes. i had the alternator checked last week and it was o.k. i've been trying to check the wiring. all the wiring seems to be o.k. i'm pulling the alternator back out to have it checked again. any more ideas? one plug on the alternator has 2 thick black wires w/ orange stripe. do those suppy the charge to the battery?

 

[Skoobie]

Yes they supply charge to the battery. They merge into one wire somewhere down the line so there is only one attached to the starter silinoid (on the same post the positive battery cable is attached to). You should be getting at LEAST 13.0-13.5 v at idle. Otherwise your battery iss gonna discharge.

 

[kr8zstang]

thanks skoobie, thats what i thought. if i pull that plug from the alt. and check voltage directly from the alt., will that tell me if it is bad?

 

[Skoobie]

Check it at the battery terminal. I just intalled a 3g alternator and I get 14.5-14.8 at idle. Minimum is 12.8 for the battery to charge I think. Sounds like you should get your alt retested at a new location.

 

[Moffa]

Could be your voltage regulator as well. Get a t-pin at the back of the alt and test the voltage coming out, It should be in the 13.5+ range if not then its your alt. If you do get 13.5 volts at the alt then you probably have a high resistance somewhere from the alt to the battery. My guess then would to either check the voltage regulator or grounds.

 

[jrichker]

Mustangs made after 85 had the voltage regulator built inside the alternator.

 

[kr8zstang]

well, i had the alt. checked again and now it seems to be bad. i'll get the new one in and see what happens.

 

[Skoobie]

Grab a 3G from a 94-95. They are 130 amp almost direct replacement alternators for our cars. Just a little wiring change and your ready to roll :SNSign:

 

[HISSIN50]

Agreed with Skoobie there - do the upgrade while spending the cash. JR's posts will cover all aspects of what you need to do to make it fit and work.

Good luck.

 

[kr8zstang]

i picked up a used alt. at a salvage yard for now and it works fine. i'm getting close to 14v at the battery. so the 3g is the way to go? i'll try to get that done maybe in a month or two, gotta lotta stuff i'm fixin on this car right now. wiring is a mess ,need a new passenger side motor mount, need to paint the fender, rebuild rear end and get new front tires. never ends. thanks for the help guys.:SNSign:

 

[HISSIN50]

If I was going to have to spend any amount of money on a 2G alternator, I would opt for the 3G instead. THe additional little bit of cost is well worth it.

Even if you dont use many accessories, you should notice a difference with the 3G at hot idle with load (at night, etc). And if you add a elec fan, etc, you are set.

The wiring for the upgrade can be done for ~20-30 bucks.

Good luck.

 

[04sleeper]

I would go with a 3G as well like JT said. It is worth it in the long run.

 

[kr8zstang]

would a 92 cougar have a 3g alt? also, is the 3g internally regulated?

 

[PRO50SC]

would a 92 cougar have a 3g alt? also, is the 3g internally regulated?

Not sure when the 3g came out but it's newer than a 92 I believe and it's internally regulated.

 

[BlownFiveLiter]

also, is the 3g internally regulated?

Yes, it's the original equipment on the 94-95 Mustangs. FWIW, I believe I paid like $99 for a reman with a lifetime warranty at Pepboys. The core is something like $25 on them, but you could get one with the lifetime warranty and be set for anything down the road that will cause more draw on the electrical system.