2003 Ford Explorer alternator/battery issues

[arctic_scrap1]

A friend of mine has a 2003 Explorer with the 4.6 in it and the battery is not staying charged. The battery was new at the end of 2013. When we jumped it, it ran fine and we brought it to my house for a closer look at it since it had been sitting for 6 months. I checked for a draw with my amp meter, readings were around .10 to .40 amps. After checking for a draw it wouldn't start again. Battery only had 8-9 volts. We jumped it again and even with the engine running I am only getting 12-12.8 volts at the battery. Shouldn't it be up around 14.5 with the engine running and the alternator charging? Or would it read low due to the battery being dead again or could the alternator be bad?

[walt501]

With he engine running you should be seeing a reading between 13.6 and 14.2 volts at the battery if the alternator is functioning properly. I just replaced the alternator on my Excursion diesel because I was only getting 12.2 volts at the alternator with the engine running and I needed a couple of jump starts while in Ontario, something I don't like but I always carry jumper cables in the truck - usually for the other guy that has a vehicle that won't start.

I went with an upgraded alternator with more amps output from National Quick Start Alternator. After the upgrade, I'm reading exactly 14.2 volts at the battery with the engine running.

[Jeremy airjer W]

it had been sitting for 6 months.