911 Charging system

Dmac72 · 10-03-2005, 12:02 PM

I have a 1984 911 Cabriolet and there is something wrong with the charging system. I just replaced the alternator and the battery with new ones and when i test the system with the lights, heater, etc. on, the voltage on the system drops to 12.2 volts or below. When i test the system with no accessories on, im getting 13.4 volts. Does anyone have any idea as to what I should be looking for to solve this problem?

RoninLB · 10-03-2005, 09:23 PM

you tested at 2k+ rpm ?

jess p · 10-03-2005, 09:24 PM

Does the voltage increase when you rev the engine? Your
voltage should be in the vicinity of 14.1 to 14.4 volts.

76 911S
81 911SC
66 912 V8
66 912 2.2 with nitrous
70 914 project car

Dmac72 · 10-03-2005, 10:06 PM

yes, i did test under a load at 2000+ rpm and im recieving between 12.2 and 12.4 volts

RoninLB · 10-03-2005, 10:14 PM

If you installed a rebuilt alternator it's probably ng. That's not unusual.

If it's a brand new alt I'd check the alt voltage directly at the alt.

I'm assuming the starter connection, battery connection and the 14 pin eng comp connection is good.

Dmac72 · 10-03-2005, 10:23 PM

The alt is a brand new part from Porsche. The only time that I have this problem is when the headlights or the heater is on.

RoninLB · 10-04-2005, 12:51 AM

Quote:

Originally posted by Dmac72

brand new part from Porsche.

good.. if it's a local dealer tell them to put a scope on Their alt.

otherwise maybe someone has a better idea ?

stlrj · 10-04-2005, 09:36 AM

Your battery must be fully charged for the test to be valid.

Joe