The battery that will not die – Ungooglables

May 20, 2008

Seriously folks, I’m staring at a 20+ year old battery that still shows full capacity according to my voltmeter.

The battery in question is a tiny BR2032 – which is strange, considering most go by the name “CR2032” – maybe because this one has solder tabs attached to it, making it board mounted? Anyway, it’s a BR2032 battery attached to a Panasonic T33 electronic typewriter that’s totally circa 1980.

This battery seems to be a battery backup for the logic board’s text memory, before there was Flash ROM (e.g. Nintendo battery-backed cartridges). What I really don’t understand is why it’s still showing a charge after 20-plus years. It’s a one-way battery! It discharges. It’s not rechargeable and there is no charging circuitry on the board. But that’s the only way I could explain how a 3v battery THIS OLD can still show 3.1v when hit with the voltmeter (and checked, and double checked, that it was unplugged from the wall).

Whut the crap. I have no idea what to say about this. All’s I know is, now this odd piece of curiosity is out on the internet, in a vain attempt at finding anyone else with a similar, eh, well, not really problem, but experience. May the Google gods smile on you, oh fellow searcher! 😛


One comment

  1. CR Batteries are coated with Manganese Dioxide for conductance, which is very stable and cost-effective. That BR battery you have is coated with Poly-carbonmonofluoride, which is a synthetic material that has a much higher energy density, allowing for much longer shelf life. Normally the shelf life for the BR2032 is 10 years, but can be longer if the battery is maintained at a stable environmental temperature with medium humidity and low atmospheric static. 20 years though… I guess you could say they don’t make ’em like they used to!

    It took some doing, but I got my hands on a physical copy of the service manual for that RK-T33, and the on board memory is EEPROM. This means the battery is only used when writing to the memory as it applies the specific current the chip was engineered to use when writing to its memory. This helps explain how your battery has lasted this long.

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