Oddbean

Voltcraft has this charger: https://www.conrad.com/en/p/voltcraft-button-cell-charger-li-ion-rechargeable-button-cell-200520.html And these batteries: https://www.conrad.com/en/p/voltcraft-button-cell-rechargeable-ml-2032-lithium-65-mah-3-v-1-pc-s-2542815.html Same brand, must work, right? Guess what? Doesn't work! As many of the reviewers pointed out over the years.

I ended up getting this boutique charger shipped from Australia (which took more than a month because Australia Post still uses camels): https://www.tindie.com/products/rezwan/ml2032-coin-cell-battery-charger/ I'm still measuring how it performs, but so far it seems to only add a few weeks of fuel to the Voltcraft batteries - perhaps they're not compatible. And only a few DAYS to the Maxwell ones. Could be an issue with those batteries, something with the charger or something about the devices I use them with. Still experimenting. I've never had any such issues with AA and AAA rechargeable batteries which I've used since walkmans were still hip (not the same ones of course, but I seem to lose them faster than they die on me).

One hypothesis I'm still testing is that the devices incorrectly estimate the battery is almost empty while in fact it's fine. Especially if the charger says it's done with those after less than half an hour.

I prefer to have a fixed supply of batteries that I occasionally recharge over having to buy new ones and safely dispose of the old ones. It's cheaper too over the long run. But not if they last 50x shorter.

I was wondring the same, I read that you could even charge non-rechargable cell if you chaege them at very low current but never tried it (still risky). For my use case, a meteo sensor, I end up modding it a bit to have a small Lithium battery with usb charger but it was more costly than a lifetime of cells probably and time consuming to mod it. In the end I'm not even using it anymore. If you find a real solution, I'm interested.