Towed vehicle battery dead upon arrival at destination

[T’sOVR&Explore]

That idea of using a jump box as the independent power source for the brake is really smart, since it is then a dual-purpose carry. And, by "Murphy's Law", having the jump box gets you a pass on ever needing to do your own jump, since Murphy seemingly prefers to hinder first those who lack carried resources!

 

[DKRITTER]

Start with a process of elimination.
Find the wiring diagram "on line" for the plug on your Bay Star. Figure out which is the correct pin that charges the battery on your toad and test it.
Also have the battery in the toad tested to see what king of shape it is in.
Work up or down the chain from there.
Last but not least is a Jump Box one of the greatest things ever made.