Well I pulled the 3 trucks off the trailer and looked them over. 1 has 3 batteries. 2nd has 3 batteries and a charger wired in. 3rd has no batteries.

Tried turning the 2 trucks on to see if they had any juice. Nothing. Not surprised.

Grab my extension cord and remembered I needed a new plug. Cheap HF replacement didn't last me 2 weeks.

Get the new plug and put it on.

Plug into the truck with built in charger and nothing happened. No hum, needle didn't move. Did some searching and I guess it needs a minimum of voltage to "tell" it to kick on and charge. Can anyone confirm that? Is it possible to "trick" it into charging? If not I'll continue with the 12 volt charger like I am doing with the other one.

So I went to the other truck and disconnected the cables and put a charger on one. Seems to be holding a charge from what I can tell on a multi meter. Have it charging the 2nd battery now.

Time will tell what kind of projects I got myself into.