Originally Posted by HighLonesome
If the system voltage is slowly decreasing until stall it means the alt isn't working or disconnected. He should be measuring around 13.8+ volts at both the battery and alt.
or the battery isn't holding a charge.
i've had 2 batteries tested that measured around 14. and they died right away when you put a load on em. one of them was my fancy 3 yr old Optima redtop........ lasted 3 years and 4 months...... just long enough to get out of warranty. best 300$ i ever spent................ (sarcasm and lies)
just saying don't overlook the obvious stuff first! no juice leads to battery/alt 90% of the time.