I am having problems with my battery continually being drained under moderate load conditions. When the car starts up it seems to be fine, the terminal voltage on battery rises normally(around 13.6 to 13.8V) and begins to recharge drawing ~ 4 to 5 amps. As long as the load on the electrical system remains below around 12 to 15a everything is fine however when I turn on the headlights, stereo, rear defroster, blower, cooling fan etc.. and current draw rises the terminal voltage will drop to the 12's and battery will begin to discharge. I have tried to isolate by taking measurements on all running equipt. individually, the headlamps draw the most at 11 amp but with everything running minus the stereo which I removed from the vehicle to eliminate from possibilities total system current draw will never exceed 30a without the alternator connected. This is well below the 65a rating of the alternator. I have replaced wiring between the battery neg. and frame and frame to engine block, as well as from the alternator pos. to fuse distribution box. I replaced the alternator twice and still have the same problem. I am not sure what this leaves aside from the possibility of a faulty voltage regulator in the alt. or the possibility that the alernator does not have an internal regulator I purchased this from advanced auto parts and they assured me it was the correct part. It does fit and looks similar to the original and has the right connectors. Any ideas on what I might be missing? Does anyone make an aftermarket alternator for this vehicle at higher amperage rating than stock?

 

So is your battery going dead at times or slow cranking? What happens to terminal voltage when all of the loads are on and you increase engine speed to 2000 rpm? Alternators do not crank out a good voltage under high electrical load and low rpm. If voltage rises noticeably when rpm's are increased you might look into a slightly larger alternator pulley so that the alternator will spin faster at low rpm's. Am assuming that your battery is good as well.

 

Smaller alternator pulley will spin the alternator faster at low rpm.

 

doh!!!! Open mouth, insert foot. Thanks for the correction spark3542.

 

I guess you were thinking larger pulley on the crank, babyhuey...

 

92dxer, I am having very similiar problem with my 95 Protege. Please let me know if you resolve this ! I bought my alternator at NAPA. I have changed the battery twice and had it in the garage to scan. Only code was O2 senscor. I do not know the voltage or amperage but will test tomorrow (saturday). I would appreciate any help Thanx !