my 1985 32 valve has a charging issue that searches have yet to answer. I put a new voltage regulator in my alternator/generator and my charging system will not charge until I rev the engine to 1500 to 2000 rpm than it puts out 14.4 to 14.8. I am tryin to figure out why it has to be reved to get the alternator to charge. Before you rev it the volt meter guage is at the bottom and the alternator shows 11.7 at the alternator. I read about an exciter wire next t the large wire on the alternator and was wondering if this has something to do with it. The problem was also there before the new voltage regulator was installed, but the charging system seems to be putting out more voltage afterthe new regulator was installed. Also the guage shows 12 volts when the system is putting out 14+ and I can't figure out why the difference. Mark

 

my old 84 did this, and i was never able to fix it.

at the shop, they would be doing some tests, and while it was running, drawing the normal 10amps, it would kill the battery unless they reved the engine to 2500rpm and all the warning lights clicked off.


mk

 

Mark,

Sounds like you have a problem with your exciter circuit. It could be the warning light bulb has burned out, a bad resistor/wrong value resistor or a break in the wiring. Concerning the gauge, there are at least 7 connections from the battery to the instrument panel, so any corrosion can cause it to read low.

Dennis

 

Mark,
More information forthcoming would help. You mention a new voltage regulator - what lead to this? what problems where you having? and last but not least - which alternator do you currently have installed.

Now for a quicky with the current info -
I would guess that your exciter current is working - otherwise you wouldn't get 14.4 above 2k. You should however continue to have an output even at lower rpm as the residual magnetic force holds in the windings. HOWEVER - if you have a shorted, or open diode in the diode pack - you will loose output at lower rpm, and your true output will be a lower amperage. The alternator works with three windings and 6 diodes. Any one of the above quits working and it will began to overheat - taking out voltage regulators accompanied by further melting of the insulation.
As you have your access - take a long screwdriver - put one end up against the alternator and one against your ear - I hope you know which end goes where. Does your alternator have a whining sound - this is feedback from the windings.
The best tool for trouble shooting the 928 is this
http://www.nextag.com/UEI-DL49-CLAMP...36/prices-html
It works fantastic for finding battery draw - fuel pump wear - etc.....

 

+1 on the burned out bulb. My bulb has been out since I've owned the car, and I've always had to rev the engine to get the warning lights @ startup to turn off.

My previous battery lasted 5+ years, so I assume everything is charging properly.

 

I thought the car sat for two of those years?

 

It sat for 8 months during the first rebuild and fired right up. It died sometime during the second rebuild. However you look at it, the battery lasted for 50K miles.