low voltage causing havoc - please help!

[ckk]

Hi there

 

Wondering if anyone has any suggestions:

 

My legacy 96 GTB has been having electrical nightmares

 

Voltage across battery when off - 12.2v

Voltage across battery when running - 11 - 13.8 volts (never over 14)

voltage across alternator positive and chassis - same as above

 

have replaced alternator and same thing

have checked all fuses and nothing suspect

have checked all grounds and reground

 

have systematically removed fuses to try isolate issue but no luck

 

have had the batter y tested too - they say no issues with it but not sure - as it only sits on 60% charge no more

 

any ideas?

 

when i drive lights will flicker and can feel the alternator struggling to force more load on .. revs fluctuate at idle too

 

where to start and what could it be?

 

car was running fine and no mods .. winter coming on was the only change!

[Fuzpile]

There's a thread today about similar problem. One more knowledgeable about these suggested measuring for AC with a DVM at the hot end of the alternator or at the fuse box itself. It shouldn't show more than .1v AC (i think he said) That makes sense if your new alternator is defective-which happens. Another thing is about the battery when one cell is dieing it is about that difference of 11 ish volts while running to max 13ish. Other owners report around 14v charge. Borrow a good battery for a test.

[Cougar]

Check the voltages on the rear connector of the alternator. The voltages there should be close to the battery voltage. Also turn on the blower to high and the headlights to high and then measure the voltage between the alternator output lead and the positive battery post. You should have less than .2 volt dropped across the connection.

 

When looking for AC voltage across the battery the engine should be running around 1,500 RPM.