82 SC charging issues

JoeyD911 · JoeyD911's Garage

Hi Guys,
Couple questions before I go tearing out my alternator. Did a test and found 12V at the battery while car is off and battery off fresh charge. Running at idle, same test shows 11V at the battery posts. This to me indicates Alternator.
While checking all connections and fuses to rule out anything else, It dawned on me that the battery warning light never came on. Sure the Fasten seat belt light came on intermittently and the tach bounced just before the battery was completely dead on a nice drive, but no warning light ever. I also noted it does not illuminate with the key in the on position. All other warning lights do come on.
I read on some older SC's that this can cause a no charge situation if the warning bulb is burned out. I s this true on an 82 or just 81 back with the external VR? I have a new regulator coming today, I may swap that out also prior to pulling the whole Alt. Is it possible to chance VR w/o pulling the alternator all the way out? Looks like there would be enough room to do so in the pictures in the Bentley manual.

Does anyone know which 12V 2amp bulb is the right one for the warning indicator light? is it the Metal base or non metal base for an 82? I'd like to pick one up on the way home and swap it out to eliminate that as a possible culprit. My luck usually runs to where I change out a 400 dollar part to find it was a 2 dollar bulb that killed me!

Finally, if it does end up being the Alternator, where are we sending the units for rebuilding, can't seem to find a local Long island< NY shop that does this on premises. Not worried about shipping it off to get it fixed, just want someone I can trust and that someone on the board has had good luck with. What about new Paris Rhone from Ecklers? any good, any opinions?

theiceman · 07-08-2013, 06:38 AM

i dont know about most of your locally rebuilder questions but i stroingly suggest repairing the warning light/ exciter circuit before tearing anything down... Have you noticed the indicator light on the dash before or has it always been off ?

I would suggest that if the light recently went out and you have no charging now , that it is unlikely to be a coincidence.

JoeyD911 · JoeyD911's Garage

Iceman, can't say for sure if the light ever worked. Have had the seatbelt light coming on for quite a while. Should have addressed this sooner I guess. Still need to know the right bulb for the 82, metal or non metal base? Pelican catalog is no help on specs for this.

DaytonaCoupe66 · 07-08-2013, 07:27 AM

Joey; checked the bulb in my 1982 930 last evening. Silver metal base on the bulb.

JoeyD911 · JoeyD911's Garage

Can I use the oil pressure warning bulb in the battery warning light socket just to test the theory that it's the bulb burned out causing the no charge issue? Can't seem to find this bulb anywhere local and I want to do some wrenching this evening so I can order the alt, if need be, soon. Don't want to wait a week for a bulb and delay the driving season any more than I need to.

turborat · turborat's Garage

A burned out "Alt" or "Gen" lamp will keep the alternator from charging for sure. The charging circuit uses the bulb's filament to complete the circuit that "excites" the alternator into a charging state.....even though the bulb is not lit.

lonewolf · lonewolf's Garage

Quote:

Originally Posted by turborat

A burned out "Alt" or "Gen" lamp will keep the alternator from charging for sure. The charging circuit uses the bulb's filament to complete the circuit that "excites" the alternator into a charging state.....even though the bulb is not lit.

that is correct ,you need a working light. check yours first and see if it looks burnt out. if you have another good one that fits try it .

the Alt warning light for an 82 is bigger than the early ones.

JoeyD911 · JoeyD911's Garage

I'll find this out tonight when I take it apart, but is the oil warning light and battery warning light the same bulb type? Can I just use the oil bulb in the battery bulb location as a test?

turborat · turborat's Garage

All the alternator is looking for is a closed circuit. Just about any 12 VDC bulb will work if you can figure out how to make the electrical connections. I cannot remember all of the different bulbs in the instrument cluster. Its possible there is a duplicate bulb.