While driving yesterday, my 2005 Ford Explorer XLT truck's battery light came on. It would come on, then go off, go on. Etc. I use cruise control and there weren't any major hills, bumps in the road, or anything else that I could see trigger the light. I immediately took it to a mechanic and they checked my battery and alternator and said both were fine (and of course the battery light never came on for them). I asked them to take it for a drive and re-test it. When they did, they said the battery wasn't charging up like they expected, but the alternator was still fine. They replaced my battery and I picked it up. On my way to work this morning, my battery light came back on (off, on) again. Any ideas what might be causing the issue? It may be a seperate issue, but the truck sometimes has issues recognizing my foot is on the brake and won't shift out of park (I have an automatic).