Are you sure the battery is good? You can use a digital multimeter across battery posts, the generic spec for a full charge is around 12.6 volts. If the battery is down, take it off and get it charged. You shouldn't let the alternator charge a down battery.
With a full charge, start the vehicle, take second reading across across battery posts, the second reading should be higher than the first, if charging system is ok.
As far as battery drain, with key off, the old way to test, was take battery cable loose, use a testlite between cable and battery post, if lite came on bright, you have a drain. Make sure no lites on anywhere, under the hood, interior, anywhere. As far as lites, the best time to check is in the dark.
If no lites on anywhere, then you pull/replace fuses one at a time, when you pull the fuse on a problem circuit, the lite goes out, then you check everything on that fuse circuit.
Sometimes a faulty alternator can drain battery, but the alternator is new, correct?
Monday, January 20th, 2014 AT 2:54 PM