That is freaking cool mate! If you could provide a link or something like that (how is the pump named? Is there a serial number on it or so?) - if you bought that pump in the internet would be cool :P
I wanted to buy a expensive pump for my garden to have a shower but this is muuuuch cheaper and easier and more sustainable because of the rechargeable battery (I have some from old vapes ;))
But anyways: this is kind of #awesomediycontent and I would like to see more of these easy hacks to turn something not sustainable into something rechargeable :)