Apu plug-in spots?

I'm trying to figure out if there's a list of places that I can plug in my truck because I have one of the plug up does anybody know a list of places where I can find one

 

All they told me is I have to plug in my truck to a 3 prong to recharge my apu if I have to sit more then 8 hours and don't want to burn up

 

I also have a plug to so where do I plug them in it

 

My truck says apu on side and other side I have a battery pack and then plug on driver side the battery's charge when I'm moving but if I set more then 8 hours it discharges the bats and need to be plugged in and I can't idel truck none of the tricks work and they don't have the thing where when batteries get low truck turns it self back on

 

No the truck charges the bats on side of truck while it's on then those bats keep apu on when the side bats run out apu goes off I can plug in the truck to charge the side battery though