Careful batteries can explode or go on fire. Here I show you how to open Vax ONEPWR Blade 4 CLSV-B4KS 4.0ah battery pack and the type of batteries inside. Be careful as batteries can go on fire. Honestly this battery lasted about 20 re-charges before going dead. Even though we followed the instruction on re-charging to the letter. They won't replace it. New battery pack £80!! Worked fine at the start but the cleaning ability faded. We cleaned the filters. In fact in the end I took the thing apart to clean so it was like new. Still you would push dirt around the wooden floor rather than sucking it up. I think the batttery was gradually dying.I bought a £65 corded vacuum cleaner. Less than the battery cost. Much better suction and you don't have to carry it like the Vax. And don't worry about the battery going flat half way through cleaning. Most likely it cost about £3 per use. Like a subscription to Vax. So I've stopped my subscription.