Per Heinz Schmitz:
The manual of my Philips Sonicare says, that the battery
is "not to be replaced", but on failing the whole unit should
be dumped.
When I discovered that, I decided, never to buy a Philips
device again.

I went through one rechargeable electric toothbrush and learned
my lesson.

Now I use the most el-cheapo Braun that has the circular brush
and takes two AA batteries - that last a looooong time.

I think a pack of three replacement brushes costs more than the
entire device - with one brush on it - does.

I don't do it, but one can always opt to use rechargeables....
--
PeteCresswell