Replacing the battery in my electric toothbrush

I haven’t soldered anything since school. When we decluttered the flat some years ago, I gave away all the soldering gear of my dad. But this year, I finally soldered again. I upgraded my electric toothbrush with a much bigger battery, going from an aging 700 mAh to 2300 mAh.

As we have three of those Braun / Oral-B Vitality (Pro) toothbrushes, I was thinking it might be worth it to try to repair one and see if I can replace or maybe even upgrade the battery. I had to recharge it every second day, and often it stopped working in the middle of my teeth-cleaning routine, which was getting very annoying.

I could have bought a new toothbrush for something like 18 €, but instead decided to get a soldering iron. After some research I found the Pinecil v2, which is small and can be powered via USB-C, so it is not wasting too much space. Add to that a little soldering iron stand, a soldering pump, some desoldering braid, and, of course, solder. All together about 55 €.

First, I opened the toothbrush (this one is the type 3709) following one of those countless tutorials online, then I tried desoldering the four contact points that hold the motor and battery. That part was especially challenging for me, as I haven’t (de)soldered anything for a long time, and just using a computer keyboard and mouse the whole day also isn’t training my fine motor skills. But ultimately I was able to do it.

I took out the battery, which turned out to be a 700 mAh NiMH one, luckily about the size of a standard AA/Mignon/HR6 battery, and searched for replacements. I found a new one with 2300 mAh and U-style solder tabs for about 7 €.

As soon as it arrived, I soldered it together again. That part was much easier. I also cleaned up the plastic parts, let them dry, and then put everything together again. Let’s see how long the new battery lasts!

Now that I have the soldering iron and revived some soldering skills, I will probably also take a look at the other ones in the household to see if I can upgrade them as well, as all of them are aging already.

What still sucks is that there isn’t really a more easily repairable toothbrush on the market for a reasonable price. Is it expected that you throw away the old one just because the battery is degraded, but everything else is still perfectly fine? Given it’s basically a simple AA rechargeable battery inside, why not make it easily swappable? You can’t tell me it’s too dangerous because of electricity; it’s pretty low voltage. And about the water sealing: There was no glue anywhere. Stop e-waste!