I’m not really sure where to post this, but wanted to share that screwing a 1/4-20 bolt into the bottom hole of my otherwise-sealed Philips Sonicare 4100 and just pulling on it successfully opens the toothbrush. An M6 screw might work too; M5 is slightly too small. Philips says to use a hammer to open it, which is absurd. The battery is still soldered, but in my case that wasn’t what I needed to repair anyway.
Apparently other brands are designed to have replaceable batteries. Don’t buy Philips Sonicare.
How long did your battery last?
I bought a Sonicare around 15 years ago, and it’s still on its first battery and working fine.
I was planning to do what you did to replace the battery when it finally goes, but I still get about a week’s charge on the current one.
My first one lasted 11 years. Can’t complain.
My previous one (an older model, which had a screw in the bottom) lasted a long time. This newer “sealed” one got water inside within 2-3 years and had no screw. Fortunately it seems that opening it up and cleaning the circuit board helped.
I just checked; mine has a screw in the hole, and looks like it’s designed to come apart.
So I guess they aren’t all the same.
Most are sealed now so that they are waterproof for use in the shower.
The whole reason I had to open mine up is that water got inside, and I don’t even use it in the shower. I think they removed the screw to either cut costs or make it more difficult to repair.
Correct: newer models have no screw.