charging system problem... what else can be wrong?

[njot]

I'm trying to help a friend figure out what is wrong with a 93 SL2, in which the battery repeatedly keeps going dead. It is definitely some kind of charging system problem.

The battery, alternator, drive belt, and belt tensioner have all been replaced within the last year. Is there anything else that could possibly be wrong that would cause the alternator to not charge the battery properly?

Thanks.

 

[Seamus's Stuff]

I'm trying to help a friend figure out what is wrong with a 93 SL2, in which the battery repeatedly keeps going dead. It is definitely some kind of charging system problem.

The battery, alternator, drive belt, and belt tensioner have all been replaced within the last year. Is there anything else that could possibly be wrong that would cause the alternator to not charge the battery properly?

Thanks.

About all that is left is to replace the cables from the alternator to the battery. In fact check all the cables that lead to and from the battery. A bad cable is all I can think of...

Jim

 

[Bob Shuman]

"Battery repeatedly going dead" is definitely not the same as "battery not charging!"

Going dead over what period of time? What is the parasitic draw in milliamps measured between the positive post of the battery and the positive cable when everything if "off"?

I'd suspect possibly a bad hood, trunk, glove box, or other switch and that some not obvious light is being left on. You can usually troubleshoot this and discover which circuit is the culprit by leaving the ammeter between the battery and cable and then pulling and replacing each fuse one at a time. When you see the amperage drop, you know what circuit and have some idea what to look at. It would seem to be a circuit that is "hot" even when the ignition is off so this is usually radio/clock, horn, dash/parking/headlights, cigarette lighter circuit, interior lights, etc.

Post what you find and good luck.

Bob

 

[njot]

Both of these ideas are good ones.
I'm going to have to determine if it is the battery going dead with the car off, or if the battery is actually not charging with the car running. I don't have the car here right now so I'll have to check it out when I get a chance.

I think it is the battery not being charged, though, because my friend was saying that strange problems associated with a near-dead battery on a running car were happening. Sometimes it won't start unless it is jumped. But other times he'll be driving it and th car will misfire and many different lights will come on on the dash.

I don 't think the second problem would happen if the alternator were able to charge the battery back up.

This is also exactly what happened when the alternator went out, so I am thinking it is something causing the battery not to be charged while the car is running.

 

[njot]

OK, let's say it's one of the battery cables, or it's the cable between the battery and the alternator. How would I test these things to find out if that is what it is?
Thanks.

 

[Pbadgley]

Check each of the cables where they connect to the battery or the alternator. most times its as sipmle as cleaning them with sand paper. look to see if those ends are worn or the cable is frayed and replace if necesary

 

[njot]

It turns out you all were 100% right!!
One of the battery cables was loose somehow! That's all it was! Tightened it up, charged the battery back up (which was near dead again), checked to make sure the alternator was charging, and we're back in business!!! (My friend was literally about to junk the car over this problem because he was so frustrated- it had been going on off and on for a few days and couldn't figure it out! He was afraid to drive it!)

Thanks!