Firstly,welcome to the Forum.
As it happens mine, on a 94 NA, refuses to retract fully sometimes, and sometimes "finishes" retracting on the move, then extends itself again.
My garage reckons it it the sensor mechanism within the unit.
No info regarding battery, but I've a fit & recent Westco installed.
I am just going to remove it...'tis a heavy & ugly thing anyway...and fit a thin wire job. Fine if you have a lock up & safe work parking though.