Basic: Trying to hookup 20v Decker lithium battery - to a 20V four wire Hoover vacuum. Same parent company.

[HarveyCat]

Looking at the third photo down and the black vacuum orifice and then comparing it to the slotted cuts surrounding the battery . . . . surely you're loosing ~ 50 % of your suck capability with that air leak fallacy.

Luckily the electronics area is above the sealed vacuum container area - the lid is two layers thick with the bottom of the black one being air tight with rubber gaskets and all - so no air leak at all - and even better no dust or dirt. I will post a better photo - the hose looking connection is misleading in my photos - once the two halves (top and bottom sections) of the top lid are put back together that hose connection mates up with another one and seals. Trust me.