Electrical problems 01 f250
I'm having some trouble with my glow plug relay. I replaced it last year about this time along with my batteries and everything worked fine. This year I was starting to have hard starting problems again. I checked the relay and sure enough it was not working. I replaced it and went to start the truck and it was dead! It turned over maybe 2-3 times then nothing. I charged both batteries over night and the next morning it was fine, it started strong for the next couple of days. Thismorning however it took a little longer to stary but did on the first try. As I drove to work I noticed that the volt meter in the truck looked a little low, by the time I got to the parking the CD player started to go off and on and the ABS light came on. Looking at the volt meter it was hovering just above 9 volts. I pulled the batteries and put them on the charger. Both were at about 30%. If my alternator is bad should my truch have been able to run on just battery for 3 days of light driving (15-20 min trips)? Also how long is the glow plug relay supposed to last?