93 ranger periodic loss of electrical power when starting

93 ranger occasionally loses all electrical power when starting for about 10 minutes then starts fine for a few more times, then it happens again. Battery is fine. What allows battery power into the vehicle?

1 possibility might be the starter selonoid when it goes bad sometimes you'll get nothing when you turn the key over to start the truck. this could also be in the ignition switch or some sort of safety switch