Firstly: 12v system, new battery, new alternator, new complete wiring harness.
Anyway, I took my truck out for a long drive today. I noticed on the voltage gauge, the whole time I was driving it was reading about 11.5 volts. The battery is brand new, and I checked the voltage before I left this morning, about 12.7.
I thought that when you're driving, the alternator is charging the battery and it should read over 13 volts when driving. Mine was around 11.5
As an experiment, when I was about 10 miles from home, I turned on the electric fan, headlights and heater. By the time I pulled into the driveway, it was down to 10 volts.
So, my guess is that the battery is not charging when I'm driving, and that when I'm running my accessories they're running off the battery and not the alternator? The alternator and battery are brand new. It's a 3 wire, externally regulated alternator. I don't know the age of the regulator.
So what do you think? It's my understanding that the accessories don't actually run off the battery, but rather the alternator is supplying the voltage. The battery is just for supplying the initial juice to start it up.
So after a long drive and running a few accessories, a battery started the day with a reading of 12.7 volts, and now is around 10 volts.
Could I have hooked up the alternator incorrectly?
