Not actually rechargeable.
When I first got the toothbrush, I put it on the supplied charger, but no lights came on.  The charger is USB-C, so if you don't have one of those plugs, you are out of luck.  I charged it overnight, and used it for 30 days.  Eventually it needed to be charged, so I put it back on the charger, no lights, nothing.  I'm outside the warranty, so I'm outta luck.  It did actually work for 30 days, so that is why I gave it two stars.  Seemed to clean good, but typical Chinesium junk.  I harvested the battery to recycle.
Rating: 2 stars