Downer on Prom Eve

[Erakad]

Sad story...trying to get the p-car ready for a son's prom....perhaps wishful thinking...sigh

Dang -- just got her back from having heat exchangers installed (short story on those was, "worst I've ever seen....had to drill out all 12 studs!")...anyway, just about home, sun goes down, lights go on and Dang, the alt/battery light is on. Get her in the driveway and dies (phew, close one). Here's what I got. Charged her back up, engine on no other electrical stuff on volts at battery=12.2. Engine on, light, radio, fans on volts at battery=11.8. Hmm, must be alt. Removed it and took to shop...
A-ok! Battery=A-ok (but give it a full charge). Usual grounds are well connected. Re-installed alt and battery, slight improvement in volts at battery (did some cleaning on connections, etc, engine on no other electricals volts=12.3, all power on now volts=12.1). Better, but still not even close to 13.

Before I take it to the electrical guys, anyone have any additional places to look/usual suspects?...not much in archives other than above....sigh

[BGCarrera32]

Here's my brain dump...

#1) make sure an automotive electrical shop checks the alternator on these things- not an auto parts store or local tune up shop.

#2) check for corrosion at engine block where negative alternator cable jumps from engine to alternator (if its like my Carrera it uses one of the case studs) you'll have to get your hands back in there after you pull the alternator again...

#3) transmission ground strap tucked in forward of transmission bracket/mounts underneath car

#4) if battery is 3+ years old its probably getting to be that time anyway

#5)could be a sign that the son really shouldn't be out alone in a P-car with his prom date...(sorry couldn't resist)

Good luck-
BG

[jester911]

I agree with bg. If your alt is charging properly, it has to be a ground.

[john70t]

I think a freshly charged battery should be 12.6V+.
12.2V is %50 charged and the lead/acids don't like to stay discharged very long.
Mabye try 2 amp charging it for 5 hours and using a specific gravity tester on the acid.

[bell]

you're belt isn't slipping is it? that'll keep it from charging.

[jason2guy]

voltage regulator?

[Erakad]

Thanks guys -- will put her up and check the grounds again today. I agree, it's gotta be the grounds...but...

I did take it an alternator shop, they said yea, jumps to 75 amps as soon as they spin it, was putting out the correct voltage...they even checked the battery, and although not new, they said it had more than enough cranking power. Hmmmm.

I'm truly clutching to take the the alt out again, not technical - more time consuming - will save as the last resort...and will end up saying you told me so.

BG -- you may be right, it may be a sign (been coaching him all week, don't do this, watch out for that, and ugh...look out for that pot hole!)

IF I can fix it, I'll let you know what the CRB was.

[billwagnon]

"you don't want to get mixed up with a guy like me..........

there's things about me you wouldn't understand...
things you couldn't understand...
things - you shouldn't understand.

[rattlsnak]

voltage regulator, as stated above.

[pwd72s]

Don't the SC's have the alternator with an internal voltage regulator? I guess that's no guarantee against regulator failure, tho...

[plain fan]

I had this same problem with my 78 SC, it had an external regulator even though the alternator had an internal voltage regulator. After replacing the alternator I had the shop pull the external one, they didn't know why it was there.
Rob, did you take it Dumont's?

[ejm914]

Check the connections at the starter. The alternator is connected to the battery via the battery cable post on the starter. You could have a loose, corroded or mistakenly left off terminal there.

[Erakad]

Bingo -- Ed, you got it! Terminal was broken! Replaced and got son off to prom (see other post), literaly as it was time to leave...gonna post his pict if I can get photoshop to cooperate.