Protip: when a seller says that something contains a new battery, check the battery anyway. That's two things saved tonight.

So here's the total: I removed the battery on an SC55, SC88Pro, MU90, and JV1010. All were leaking to varying degrees. I still have to open up the JV1080, but I'm sure that'll be leaking too. Should have probably taken the battery out when I opened it up last time, but it didn't look too bad when I glanced at it, but all of these the leaking was hard to see from the top. It was all over the bottom of the battery.

Luckily, every single one of these batteries was in a plastic holder, which I think is the main thing that really saved me, especially in the case of the MU90 which had the worst leaking of all. That one was flat out disgusting.

Wow, I think Ive seen maybe one or two leaky 2032 cells in my life, AFAICR.

I have seen non expired alkaline AA batteries suddenly reach the threshold of suddenly triggering a low battery indicator AND being found to be leaking the next day (admittedly, they might have started leaking before the low battery indicator lit up). These were cheapish ones (local pharmacy branded).

These are the only ones I have ever seen that were bad. I opened up the Jv -1080, and that battery was fine. The jv-1080 battery had lithium written on it, I thought these were all lithium, but I’ve heard there are also non-lithium coin cell batteries too? That’s the only thing I can think.

It’s really strange anyway that all 4 of these were bad given that I’ve also never encountered a bad one before. Guess it just goes to show you should always check!

My MU50 finally started to complain about low battery. When I got it 5 years ago it still got decent voltage. So around 25+ years and no leakage - not bad at all. Can't see manufacturer behind spotwelded contact but "Made in Japan" is clearly visible.