major electrical problem

[Ryan Rønning]

I got the battery light on the dash the other day. Alternator is not charging and the batteries are being drained. Unhooked from the truck each battery has 12.5 volts. When I look up to the truck the batteries very very quickly drop from 12.5 volts and are dead can't even get the lights to come on unless hooked up to the battery charger and even then very dim. Charger can only had the batteries at about 7 and a half volts. So my question is is this the alternator and will it go away once I replace it or is this something else?

[Ryan Rønning]

Bump up. Please help

[dhanna6powerstroke]

If your alt is bad enough, it will drain the batteries.

[Ryan Rønning]

Thats what i am thinking. I hope it turns out to just be the alternator.