Okay, my truck starts just fine. After starting, the lights are dim and it seems to be running off of the battery for approximately 5-10 minutes and then the alternator starts charging the system. I can't figure out why it won't start charging right away. I have had both the battery and the alternator tested (both good). I would appreciate any help that you could provide. Thanks

 

bad connections both positive and ground? How or where were they tested?

 

I had it tested twice at O'Reilly's. I upgraded to a 200amp alternator and the big 3 kit from XS Power. The connections were ran to the same places as stock. I stripped the wire with the useable link running from the alternator plug to the charge output. I can't figure it out

 

I've never heard of a big 3 kit, just looked it up. Just replaces stock wires right?

Did you remove the alternator from the truck and have it bench tested, same with battery?

Testing in the vehicle may not reveal a problem with either.
A load test on the battery might show it isn't holding a charge or has gone south.

A simple at home test for the alternator is to start the truck and unhook the battery. Turn EVERYTHING on, if the truck dies your alternator isn't providing enough Amps to run everything AND charge the battery.

Most parts stores that sell batteries have a load tester or battery analyzer that stresses the battery to see if it's any good

 

NOT recommended with all the electronics on today's engines.

 

I did suggest pulling the alternator and having it bench tested initially

 

Not sure but fords have a problem with the small little wire that plugs in on the alternator breaking at he connector or too loose causing a no charge problem.