When I run the car on days usually over 80.

ANONYMOUS

MEMBER
1993 BUICK REGAL
90,000 MILES

When I run the car on days usually over 80 degrees and have the A/C on, the battery dies very quickly. If the outside temps are say 75 or less the battery will not die. The hotter the outside temps the quicker the system dies when running the A/C. The battery and alternator are newer and were replaced at the same time. There is also a newer clutch on the A/C compressor but the compressor is original. The car has a 3.8 liter engine and is a Regal GS 2 door

2 Replies

CARADIODOC

MECHANIC
33,871 POSTS

Have the generator professionally load-tested. If it only produces exactly one third of its rated current and "ripple" is very high, it has a bad diode. A common size is a 90 amp generator, and 30 amps is not enough to run the entire electrical system under all conditions. The battery will have to make up the difference until it runs down.

These generators have a real lot of trouble due to their design. If you have to replace it again, replace the battery again too unless it is less than about two years old. These generators produce huge voltage spikes that destroy the internal diodes and voltage regulator. The battery dampens and absorbs those spikes but as they age and some of the lead flakes off the plates they lose their ability to do that.