I have a dump trailer that has a 12v car battery to operate a hydraulic pump. I am wondering if anyone knows how I can keep this trailer battery charged.
I have a auxillary terminal on my trailer hitch plug but I dont think it would be a good idea to connect that pin to my positive terminal of the trailer battery because when the trailer batt is dying isnt this going to try to draw current thru this wire connection and melt the wire??what can I do?

 

A possible cheap and simple solution: connect a 45/50W car bulb (paralel the two section) serial with positive wire. It enable about 5A charge current for discharged battery,"visual control by light intensity" and short circuit protect.