Great little shaver that deserves to get a second life

If you want to do this, make sure you have a proper soldering pen (i used the $40 weller wlc100.

Batteries are identical in size and have longer charge (I am still on the first charge and it's been almost a month!)

The reason I didn't give it 5 stars?

The welded on terminals are centered and the OEM batteries are slightly off center, so when you go to add them you have to carefully bend the soldered tabs to match

Technically not "exact" replacement

And as others have said make sure you fully document the alignment of the old batteries before you desolder them off...take the new batteries and get them lined up before you start soldering. There is no wiggle room, the new batteries have to be exact or it will not reassemble properly