damon

Ok I have posted this before, but here goes.

I have an 85 gs with an 85 motor (bought from so on this forum) with and 81 alternator and a duralast gold battery with 740 cca. the car ran great for 4 months then all of a sudden it stopped charging the battery. I have check all of the fuses on the strut tower and in the block under the dash. I replaced the alternator with a new one (same model being it has a lifetime warrenty) replaced the battery and checked all of the connections from the battery (three ground points and two power points) to no avail. What in the hell is keeping it from charging?

The only thing off the wall that I did before this happened is give a guy a jumpstart.

It is so bad that if I put a fully charged battery in and drive it the batt will read less than 8 volts in about 5-10 mins of good ole fashoned rotary driving.

HELP ME PLEASE!

peace

Manntis

you DID shut off your car before giving the guy a jump start, right??

djmickyg

have u checked to see if the altinator is charging by usiung a volt meter on the back of it??

if thats charging then it might be voltage regulator?

marshp

why do you have to shut off the car?

Manntis

Leaving your engine running leaves your electric circuits open. When you hook up to the other car and they start their engine, initially they're drawing current from your battery and theirs in parallel to power their starter... no problems there, as it's 12V with high amps drawn by the starter to crank over the engine.

However, once their car starts and their alternator kicks in a power spike is sent back through the cables and into your harness. This can do anything from absolutely nothing, to blow a diode (in older cars like ours), to fry the engine management computers in newer vehicles. Frankly it's not worth the risk when all you have to do is shut off your engine.

It is recommended if you're going to give someone a jumpstart ALWAYS shut off your vehicle before they crank theirs over, and leave it off until you disconnect the booster cables.

djmickyg

and this is more with EFI cars
but never connect the Negative plug to the negative terminal on the battery. always hook it up to the engine or some part of the metal frame

damon

I never leave my car running while jumping a car, just enough to put a little charge on the battery. On the back of my alt there is a small capacitor that slides onto the main power bolt and is held on with a nut. Is it possible that this is bad? What is it? My car has an internal regulator. I have hooked up a voltmeter to the alt and the neg post on the battery and it was reading and the reading would change with engine rpm.

peace

rotor vs. piston

What was the reading? My alt. changes voltage with rpm too. At idle it reads ~12.06 (kind to low) but running down the road it's 14.5 or higher. I'm not using my alt. as a guide, I think mine is on its death bed too.

damon

I cant remember the readings, but if I remember correctly they were a little higher than yours

peace

RotorMotorDriver

iTrader: (1)

Its supposed to be 13.5 volts under 2K RPMs...Or something like that. I dont remember where I read that, but my old alternator was varying with engine speed as you describe. I got a new one and not its 13.5 volts all the time, even at an idle.

~T.J.

damon

If I can get it started tonight Ill get some readings.

Thanks rmd

peace