I have a Chevy s10 2000 I but a new alternator my battery is good but it won't keep the charge

If you're running some high watt stereo system, the problem is it's draining your battery faster than the alternator can charge it. You will probably have to buy a higher voltage alternator.

1. Check your cable end on the positive side and make sure it's not corroded, sometimes the small wire is corroded under the rubber. 2. trace wire from Positve battery terminal to the back of Alternator, Should be smaller wire. look for breaks. 3. Disconnect battery and BAT terminal wire from the back of alternator, Ohm check this wire. 4. Check ground side of battery by making sure your negative battery terminal has a smaller wire running to the fender.