Charging problems

Topic: Charging problems (Read 1307 times) previous topic - next topic

Charging problems

November 24, 2008, 01:13:20 PM

Hey all, I read through the earlier post and got some good info, but thought I'd post my problem to see if anyone has any further comments.

My '87 3.8L TBI suddenly wouldn't start one morning. I will note that the day before on the ride home, I could tell the dash lights were a bit more dim and it seemed like the car was running off the battery only. It started fine and even after driving most of the way home in the dark, when I stopped at the grocery store, it still started fine. Next morning, though...nope...solenoid was clicking, that's it. Note that the "ALT" light never came on during any of this...and it does work.

I had the battery checked, and after a charge, it was deemed "good". Brought it home, started the car, no problems, then decided to use the "alternator check" on my battery charger. Alternator tested "bad" under load. O.k., so I figure I'll go get an alternator it appears to be the ORIGINAL! Next day I go to start the car for the heck of it...NOTHING. Battery is now down to 8.9V.

So, my question, what could be draining the battery when the car is not being driven? Nothing obvious is a problem (lights on, dome lights, etc.). I did read that someone posted in the other thread about an alternator drawing 3A when not running...

Regarding pulling fuses while checking current draw...I'm not an electrical guru, I don't quite understand what that will tell me? And, is that with the engine running, or not? Is that essentially looking for a "short"?

Oh, one other thing...what is that small wire coming off the negative terminal with the plastic what appears almost like a "fuse holder" for?

One more thing...I have the 2nd alternator listed in the photos of the earlier post..."2G" I think it was.

Thanks!

Charging problems

Reply #1 – November 24, 2008, 07:16:07 PM

Quote from: bike70ride;244569

Note that the "ALT" light never came on during any of this...and it does work.

This is typical. The alternator goes bad and the light doesn't come on.

Quote

I had the battery checked, and after a charge, it was deemed "good". Brought it home, started the car, no problems, then decided to use the "alternator check" on my battery charger. Alternator tested "bad" under load. O.k., so I figure I'll go get an alternator it appears to be the ORIGINAL! Next day I go to start the car for the heck of it...NOTHING. Battery is now down to 8.9V.

You have a fancier charger than I have. The voltage at the battery with the engine running should be around 14.5v if the alternator is working.

Quote

So, my question, what could be draining the battery when the car is not being driven? Nothing obvious is a problem (lights on, dome lights, etc.). I did read that someone posted in the other thread about an alternator drawing 3A when not running...

Yes a bad alternator can drain the battery.

Quote

Regarding pulling fuses while checking current draw...I'm not an electrical guru, I don't quite understand what that will tell me? And, is that with the engine running, or not? Is that essentially looking for a "short"?

Engine not running. Disconnect the negative battery cable. Hook a test light between the negative cable and the negative battery post. If the light lights with every thing off, you have a battery drain.

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Oh, one other thing...what is that small wire coming off the negative terminal with the plastic what appears almost like a "fuse holder" for?

This is the EEC ground wire.

Charging problems

Reply #2 – November 24, 2008, 08:52:20 PM

a voltage regulator could possibly cause the quick drain... ask me how i know :-p

Charging problems

Reply #3 – November 25, 2008, 02:30:36 AM

this buds for you,,,,,,,,just read and look at the pics i put up. Its in my diy link now.

http://www.foxtbirdcougarforums.com/showthread.php?t=19254

In a nutshell,
steal the bulb behind your light switch thumbwheel,,or go to napa and buy one. its not the small bulbs your thinking of, its smaller.

bend the tabs on the bulb outward
unhook your ""freshly charged up battery" pos post
have a couple of aligator jumper wires.

Clip from battery +cable to one side of the light bulb.
clip from other side of bulb to the + bat post

does it light up bright but goes slightly dim?

does it go out when you unplug the alternator conn?

Charging problems

Reply #4 – November 25, 2008, 06:05:47 PM

Thanks for the help, guys. With turkey day upcoming, I don't know if I'll get a lot of time to work on the car this week (my family is coming to visit). I'll let you know what I find when I do the work, though...

Charging problems

Reply #5 – November 26, 2008, 12:47:00 AM

the 84 3.8 i just got had a battery drain that was in the starter solenoid itself... had the same problem starting (just a funky clicking) and yes, the battery was 9.7 volts.... charged it up and replaced the solenoid and it's been 3 days (been checking the battery every morning and the car has not been driven) and the bat is still holding 12.48 volts each day and starts quickly.... hope this helps (solenoid is like $14 at advance)......

p.s. yes the black wire off the battery is the cpu.... i found that out when i unplugged it one day and the car just quit!

Update

Reply #6 – December 01, 2008, 01:55:29 PM

Alternator replacement did the trick! Only thing I had to wrestle with a little bit was swapping the pulley (new one was too narrow). Nice parts guy at O'Reilly zipped it off with an electric impact.

I need to get one of those!

Drove the car to work today and everythig is back to normal...

Thanks to all who replied!