Trailer Battery

G,day!
I have a trailer for my job that has a hydraulic ram for the tipper which dumps the grass bin for me,it currently has a small car crank battery connected to run the ram,thus it needs to be kept charged !My Patrol currently has a dual battery system with the auxiliary being a 120amp AGM battery which is located in the where the gas bottles were held as it a ex telstra vehicle with a pod,so can I run wiring from my auxiliary to rear of vehicle then anderson plug to my trailer to charge the trailer battery,the Trailer battery has a inline fuse connected at the terminal?Or will I have to come from my main crank battery with an isolator connected?

How long does the pump run and how much does it draw?
If it is, say, 2 minutes x 2 times a day at 15 amps for example that is bugger all

If you are connected to your vehicle when tipping I wouldn't even bother with the battery on the Trailer.
Have provision for it by all means but take it off and run the power from the Vehicle Aux via an Anderson direct to the pump

Either way, coming off the Aux via an Anderson will be fine as long as the wiring is not too smalll a guage

Thanks Evil Twin,sorry for the delay in reply have been away on holidays,I suspect the problem could be the guage wire you mentioned so may start there and see if that fixes the problem.