I can shift a couple of clicks without spinning the crank -- I don't think it's straining the motor, the chain is just at an angle.
The limit screw sounds like the problem. It needs a gap to allow an over shift. The low limit (largest cog) is adjusted without extra clearance.
I could see this draining the battery overnight. If so, riding in the smallest cog would drain it too!
OP, do you ever leave it in the smallest cog after a ride (without flipping the bike over)?
(Or perhaps the hidden top of the hood buttons? but they aren't running the motors.)
From the dealer manual DM-UL0001-02.pdf
Shift the rear derailleur to the smallest
sprocket, and then tighten the top-side
stopper adjustment bolt until it touches
the stopper at the position where the
rear derailleur finally stopped. From this
position, turn the top adjustment bolt
counterclockwise one turn so that an
over-stroke allowance can always be
maintained.
~~~
The largest cog is adjusted closer:
Shift the rear derailleur to the largest
sprocket, and then tighten the low
adjustment bolt until it touches against
the stopper.
If it is tightened too much, the motor
will detect a problem and gear shifting
operation will not be carried out
correctly.
Last edited by rm -rf; 06-11-19 at 08:36 AM.