Battery/Alternator Problem

DG624 · 08-20-2012, 03:30 PM

I have an 86 Carrera that sits most of the time. I tried to start it last month and the battery was dead...5 Volts. I got a replacement (Braille 2317) but it was the wrong type ...the posts were reversed. Before I looked I had it hooked up and then noticed it was reversed. I disconnected it and never got to start it but I am afraid I may have damaged the alternator.

Now there is some sparking when I hook up the new battery (with the correct posts). I never had this problem before. I hooked up the battery after it was charged to 13 Volts and started the car for several seconds to back the car out of the garage. The car would not restart and the battery was discarged down to 7 volts. When I removed the battery it was warm. I recharged the battery again but have not tried to restart it.

The Bentley manual says to check for voltage loss by hooking up the battery with positive pole and then using a meter to connect between negative ground and battery negative ground. Does this sound like a short power loss or a bad alternator. How can I check the alternator to determine if it is good?

timmy2 · timmy2's Garage

Check the light for the trunk, and your interior lights, both will drain your battery.

DG624 · 09:16 AM

I had a problem with the window switch sticking...but even with no accessories on it still is a problem.

I read this and it sounds possible.
The alternator can sometimes have a shorted diode that can cause amps to flow through the alternator's power cable and through the shorted diode and into the case and through the bolts and back to the negative battery terminal. This will drain a battery in a hurry.Make sure to read the ammeter before and after unplugging your Alternator.

I made a mistake when replacing the battery and maybe it did damage the alternator.

Joe Bob · Joe Bob's Garage

Well....the way to test is to run the car or to pull the alternator and have it tested at the shop.

So.....if you are a competent wrench and have a meter and a battery charger you can do it at home.

Install fully charged battery. Battery should read 12.5v +.

Fire up the engine. Read the posts and you should have 13v +

Rev to 2500 RPMS. 13.5-14.0v....over 15v is not good. Under 13 is not good.

Reversing the polarity can kill the alt, voltage regulator, radio and other electronics that are on an unswitched circuit.

Good luck.

DG624 · 08-21-2012, 09:56 AM

I will try this.....it seems I destroy as much as I fix.

rick-l · 08-21-2012, 10:30 AM

Quote:

Originally Posted by DG624

Now there is some sparking when I hook up the new battery (with the correct posts).

Some sparking??? To discharge a 90 amp-hour battery in minutes there must be a big spark. I wouldn't try the meter unless you have a handful of fuses.

I'd take the alternator out and have it checked or unsolder the wires and check the 19 (2 unused 3 for the reg) diodes with a meter.

And hope nothing else blew up.

Jdub · 08-21-2012, 11:59 AM

this happens to all of us. Important lesson on never letting the battery get low in charge - can really screw up more expen$ive parts of the car (diodes in the alt.).

In all events, have that alt. checked out. You may have been ready for a rebuilt unit anyways.

DG624 · 08-24-2012, 12:19 PM

I have removed the alternator and got a new one from Pelican...while I was replacing it I was also wondring if there is a lighter version (alternator)? I also talked to Braille about a diferent battery and they recommended the lithium version which has similar power 1100 PCA but more amp hours 90. The only disadvantage is the cost.