Today I took out my trusty calculator to crunch some numbers but it does not turn on. Strange, I say to myself, it was working just fine a few days ago and the low battery indicator was not on. So I take out the batteries (4 regular AAA's) and check their voltage with a multimeter. Three are fine at around 1.35 V but one of them registers at -1V!
How is that possible? My understanding of how batteries work is limited but I had no idea that the polarity of a simple alkaline battery could reverse. Mind you this battery used to work fine just a few days ago.