M18 Fuel 6 Gallon shop vac murdered my battery and tried to murder another.

So, this Vacuum doesn't have a 1-key system so I'm not sure why it did this.

I left one of my lawnmower batteries(a 12.0) inside of it for a good while, and it wrecked the battery.

At first I thought it was a coincidence, but then I left a battery in it just a few hours that had about 20% power left, and when I took it out it was drained.

What in the heck is wrong with this thing that it sucks batteries down so fast on idle? These are $200 batteries so not cheap to replace either.

Also, for anyone wondering - Unfortunately the warranty for the batteries didn't help me either because I bought em through home depot and my online receipt was gone from their system(they only keep 18 months which I hate about home depot).

And going by the manufacture date didn't work either because the batteries were manufactured well before Milwaukee mowers were first released.(like 6 months before, which put them out of warranty).