I've added a separate volt meters, available at Amazon, to the shutter motor battery since it's much easier to see than looking at the ASCOM Hub, and it works with the system is shut down.
I found these, see photo, 1/4" double battery terminal devices that allow two things to be attached to the battery. They can be found at any auto parts store of on Amazon at https://www.amazon.com/Ancor-210613-Electrical-Male-Female-Adapter/dp/B000NI5D92/ref=rvi_19/131-4426186-5919949?pd_rd_w=18uSC&pf_rd_p=c0296674-5a83-4ad6-b035-0702d2b359df&pf_rd_r=2Y6DY2T6EJ5ZE0T42FC1&pd_rd_r=918b5708-5912-4442-8e59-881b603ebae1&pd_rd_wg=FaWxj&pd_rd_i=B000NI5D92&psc=1
I cut a small slit in the top of the shutter motor case to allow the wires and meter to sit on top of the shutter motor and attached the meter with some double-sided tape.
I could not find a definitive answer but think it’s in the 23mA range. I’ve had these meters on a fully charged battery and have not seen any voltage drop in over a month.
I leave the shutter motor turned on all the time and when closed it is connected to the charger. The only time I see a voltage change is while the motor is operating and it usually is no more than 0.2 volts per open or close.
The difficulty I’ve experienced with the BMS shut do, I believe, is due to high temperatures during the day. However, I have not gott through to Dakota Lithium customer service yet. The two batteries that gave me fits have been successful recharged and seen ok.
How much is the current drain with your voltmeter? Is that adding to your battery drain issues?