I've charged 4x2000mAh cheap cells externally and just put them into the B&D vacuum for runtime testing.

I've used the vacuum for around 20-25 times for cleaning the cat litter and hair around the apartment.

-> 1 week without charging

I think this is enough, because I don't want to have the charger always on.

Next steps:

• Waiting for the BMS module for balanced charging
• Writing the HD instructions :-)