[pamoffa]

If you have a volt meter check the bat voltage with the truck off should be around 12v turn the truck on and it should go up to 13 or more this will tell you the alternator is working. I would check for any lights not going off when you turn the truck off. I'm not sure what lights your truck has but there can be under the hood lights back area light visor lights a week battery could be killed by this.