Trailer battery connection

|I have a trailer with an internal battery to run lights, a winch, the |trailer emergency brake, that sort of thing. My previous tow vehicle had a |charging lead so that the trailer battery was charged by the vehicle while |it was being towed. The current tow vehicle doesn't have this lead |connected, so I charge the battery while stopped with a normal battery |charger. | |I would like to connect up a charging lead, but I wonder if it should be |connected directly to the vehicle battery, or to a switched source? My last |truck seemed to have it direct, since I could run the trailer lights by |plugging into the truck, which would be handy. | |Any ideas on how this is normally wired would be appreciated.

I have a similar setup on my trailer. I use a solar batter charger permanently mounted on the top, feeding the batter. Free energy, and the battery is always hot. If I run it down a lot using the winch, I'll use a regular charger to restore the charge. Normal usage the solar panel keeps up with. Rex in Fort Worth