Battery Dying While Sitting Around

[majicwrench]

You only need one. Only advantage to putting on neg is it keeps you from arc welding if you aren't careful.
Keith

[jimmycakes401]

I think I'm killing it with the starts. Checked the battery yesterday and it holds a charge, but my alternator isn't charging it. Tested the alternator and it's good. Sooooo... there's a wiring issue. Possibly a fuse? Going to check and see if there is an alternator fuse...

[4uall]

any possible chance the alt. belt is worn/loose/strecthed etc?

[jimmycakes401]

Brand new belt. Nice and snug.

[4uall]

I feel your pain

[jimmycakes401]

I am just going to have to chase the circuit around

[jimmycakes401]

Is my red battery light supposed to be on? Just warmed up the car, let it run for a while. It started at 12.24 and now it's up to 12.3. So I know the alternator is working.

[RRoller123]

Should go out after the car starts

[jimmycakes401]

It's on when the car is running.

[jimmycakes401]

I found a bunch of threads talking about the light being on when the ignition is off and how to fix that, but not while running.

[RRoller123]

Indicates that the alternator is not charging the battery. Beyond that I guess just check all the associated wiring, as I am no expert that is for sure.

[jimmycakes401]

Is it odd that it reads as if it's charging when I test the battery and the car is running?

[focodave]

Jimmycakes,
I don't mean to sound like a know-it-all, but I will tell you that your alternator is not charging if the voltage at the battery is only 12.3 volts while the engine is running.
It needs to charge at 13.2 volts to 14.5 volts to be effective.
The best way to check the alternator is definitely by measuring the voltage at the battery terminals while the car is running.
Whatever you do, don't disconnect the battery while the car is running to see if the alternator is working.
That can reek havoc on your ECM and ignition coil module.
You need to trace all of the wires in the circuit with an ohmmeter. (disconnect the battery to do this with the car not running).
You will need to obtain wiring diagrams for this.
If everything (and I mean everything -- fuses, wires, grounds, specific gravity in each battery cell after charging with an external charger, etc) checks out, I would look at the ignition switch to make sure all connections and terminals are good.
If that checks out to be good, I would replace the alternator.
I have a degree in Electronics Engineering, so I feel qualified to offer this advice.

[manoa matt]

What's the condition of the negative battery ground wire? If it's original, replace it for $6 at any auto parts store. If you have a bad ground connection the alternator will show its charging, but the battery won't charge. At 30+ years of age the original cable has probably lost a lot of its capacity. The green insulation is likely pulling back from the end connections and the wires are no longer twisted tight. Clean the battery post and the sheet metal where the opposite end attaches.

Yeah, yeah, "Why guess and throw money at the problem?" Well, at this point in time replacing the cable is preventive maintenance like seeing cracks in hoses or belts, and its only $6. What's that saying: 99% of electrical problems are ground related?

Does the light stay on all the time or only at idle. The Alt does not start charging untill around 1100 rpms.

[RRoller123]

Yeah, good idea. He said earlier that it is on all the time.