From experience with rechargeable batteries and the Winbot, they should last a few years. It also depends on how it is used, as it needs power quickly
and you can't drive it empty, otherwise gravity will take effect. So with 2-3x charging is nothing! I don't know, but I could imagine that you could swap the batteries. It's really useful, I cleaned the balcony windows, which were "slightly" dirty from the barbecue, and after two runs they were almost perfectly clean. Unfortunately, I don't know the other appliance.