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Comment by causi | Hacker News Reader

I would suggest keeping an eye on the voltage with a meter and when it starts to drop solder on a second battery while you replace the first, the same way people replace game cartridge batteries without losing SRAM saves.

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That's a great recipe to fumble and accidentally reset the device.

How? The original battery provides power while you're soldering on the backup and the backup is solidly soldered on while you swap out the original. How could you be so clumsy you rip out a solder joint?

What if it's only held in by the case itself and not a clip? Then I'd disconnect it simply by opening the device?

Since you knew it was a CR2032 I assumed you were already familiar with it.

I just guessed by the physical size of the device. I guess it could be a smaller coin cell as well.

You are correct. Those BankID physical devices have tamper switches that erase RAM on device opening.

An alternative is debit card bankid (as a smartcard, then add Mobile BankID back), but it's being deprecated soon.

Accidentally disconnecting the original battery while messing with it. Or shorting something out.

A bit OT, but at least for the Game Boy you can pop the cartridge (front of the case off) into a console (GBA is especially good as it only covers part of the cart), power it on and then replace the battery. The game save will remain. Or you can use something like the GB Operator and backup the game save, replace the battery and then rewrite it to the cart :)

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