That sounds pretty normal to charge a 3000 and have the display read 2700.

Two things to check are the capacity setting to make sure it is more than 2700 and the trickle setting can be 0, 100 or 200 , but should be set to 200 ma and allowed to trickle after the peak charge for at least 4 hrs. This will balance the cells if they are out of balance.

The truck should be brought in or stopped at the first notice of slowing down.

A discharger can be a simple 12 volt headlight or tail light with the red and black wires hooked to it.