Have a '01 Blazer. Wife's car. The only time I get to drive it is when it needs service. The problem I can't solve is a voltage drop (alternator reading) on acceleration. When you accelerate, the voltage reading on the dash drops to about 10 or 11 (guage on dashis not specific) and the battery l.e.d. icon lights up. If you maintain a steady speed, the volt guage will return to 14. The alternator was replaced four months ago along with a new belt. I thought it was surely the tensioner not holding enough pressure against the belt that would allow it to slip thereby causing the alt not to maintain charge but I changed the tensioner and it did not change. I took my voltmeter and checked the battery; Ignition off-12.4 volts; Ignition on- 13.88 at battery & 13.93 from back of alternator at idle with DRL and A/C on. Side mount cables are clean. I am open to suggestions. Thanks.

 

not sure what type of gauge these use but its possible only instrument gauge is wrong. If you have a obd2 scanner you can check voltage in that and see if it is truely dropping. Or the other way would be to plug like a tire pump or book light or something and rev the engine and see if it changes ie light dims, or pump slows.

 

have you done a load test on the battery?

 

Yes I did a load test on the battery; It held the load also did a gravity check on the battery and it checked in the OK range. I am leading towards the alt (even though it is relatively new that doesn't always mean that it is still good) thinking that it is not functioning while under a load. What do you think?

 

sounds like something is slipping