Please read the comments below. They contain a number of important hints and sources for batteries.
Tony repaired his toothbrush using the instructions below and made a short video tutorial!
We have a nice Oral-B Sonic Complete electric toothbrush. Unfortunately, the rechargable battery inside only lasts about two years until it is more or less dead.
Asking our vendor how much a replacement battery would cost we were told to just throw away the toothbrush and buy a new one. Great.
So I had to hunt down a fitting battery and replace it myself. If you want to do so, too, follow these steps (sorry, no photos):
- Buy two GP100AFH NiMH rechargable batteries (Conrad: #250465)
- Solder the solder tail on the positive pole of one battery to the solder tail on the negative pole of the other battery. Try not to heat the battery too much.
- wrap both batteries in insulating tape so that you get one long battery
- bend the two remaining solder tails in the same direction so that they lie flat on the battery pack.
- open the toothbrush by turning the recess in its bottom a little bit counterclockwise (I think). A spring will push out the bottom cap.
- carefully remove the bottom cap. Do not damage the wires that connect it to the main part.
- push out the main part by pushing inwards the metal bar that protrudes from the top of the toothbrush.
- carefully remove the main part from the shell
- the battery is soldered to the circuit board. Don't try to solder it off. Instead, cut it off with a small wire cutter. Leave as much of the solder tails attached to the circuit board.
- remove the battery
- bend the remains of the solder pins so that they provide good contact points for the solder tails that protrude from the newly-built battery pack. If you don't understand what I'm trying to tell, either do what you think is right or send me an e-mail.
- put in your new battery pack so that it makes contact with the leftover solder tails from the old pack. Of course, watch the polarity.
- try if the toothbrush works again.
- if yes: great – carefully reassemble the toothbrush
- if not: throw away the mess and buy a new toothbrush