I recently saw a deal at my local hardware store for 3 18v drill batteries with 2ah, 4ah, and 6ah at $130. I was planning on building a battery bank out of 18650 batteries, but if I can just use those three batteries I wouldn’t need to worry about learning how to use a bms or buying a spot welder or any of that. My question is would it be safe and would there be downsides to making a battery bank by wiring the 2ah and 4ah battery in parallel with one another and then in series with the 6ah battery to get 36v with 6ah? Thank you.
