ummm doku started 2 other threads about this problem back on the 15th, no response to it yet so he came in here and did it again. DOH

as for the origional problem, 50v on a 48v battery isnt bad, its not fully charged but it should run the truck without any issues. The voltage drop during runtime is normal but if its dropping to 47 volts you might want to try charging the battery and running the tests on a fully charged battery and see what voltage drops you get, a discharged battery can fool you into thinking there is a problem when there isn't.

the lift lockout shouldnt activate will the battery is discharged to somewhere in the neighborhood of 10% depending on how the lockout is set in the truck manager. Not all mfg's set theirs the same.