Electric Toothbrush - Not sure where to post

[indieFan]

Hi Everyone,

I'm not sure where to post this, but it's about my electric toothbrush.

I bought an Interplak PB2 on ebay recently because my current toothbrush is not charging well. I put the "new" Interplak on the charger several days ago, but it is not running at all.

The Interplak runs on a 3-cell NiCd battery. Other details I found online are: 2.4V 700mAh.

These cells are at least 20 years old. Probably closer to 25.

This particular version of the Interplak is sealed against water, with no way for the general public to open them for the battery pack. One of the sites I ran across stated that a dremel was used to open it. I'm thinking an O-ring or some other seal can be used.

1. Is there a physical danger to opening the toothbrush if no apparent charge is being absorbed?

2. Is there a way to get a charge into these batteries without opening the toothbrush?

3. If a charge is possible in these batteries after opening, is there a safe way to do it?

4. If a charge is possible in these batteries in either 2 or 3, how long will the batteries be rechargeable?

Thanks for any help,
indieFan

P.S.- For those that are thinking, this is a "stupid" idea, please understand that the original Interplaks typically lasted for 10 years and did a far superior job of cleaning teeth. You can find quite a bit of anecdotal evidence of both online. I've used other toothbrushes, including newer Interplaks (after Conair bought the division of Braun), and they don't hold a candle to the original.

[Al Skierkiewicz]

Indie,
First, NiCd batteries are 1.2 volts per cell so a three cell should be listed as 3.6 volts. Normal for an appliance of this size is two cells which is the 2.4 volts you list.
Sealed appliances are generally glued or ultrasonically welded. While yours is over ten years old, I doubt that the seals on the moving parts have held up this long. That being said, it is likely that there has been some water entering the device over time.
A Dremmel tool can be used but that removes material that you will not get back so the parts won't easily seal after a repair. A technique I have used from time to time is chucking the device in a vise and squeezing until part of the seam opens. This takes a lot of patience so that you don't over do the squeeze and compress the internals.
NiCd batteries have a finite life much like our robot batteries. Often though, the battery grows a "fuzz" around the terminals that eventually shorts the battery cell. The other life limit is caused by out-gassing of the chemicals. This is a naturally occurring event that is a result of charging. Once you have the device open, you need to measure the cell length and diameter and then purchase replacement cells from DigiKey or other outlets. Generally, these size devices will use sub-C cells but not always. I would buy cells that have solder tabs attached so that you can make the repair. Batteries with no tabs have a stainless terminal that requires special flux to solder.