Mercury Coulometers

Coulometers are almost everywhere, quietly measuring the coulombs going in and out of battery packs and estimating the remaining battery capacity. Like most modern solutions they are implemented as an integrated circuit which why I was intrigued when I read a thread on the ‘TekScopes’ mailing list about amercury coulometer that was being used as an elapsed time counter to estimate the amount of time that a piece of test equipment was on. You would never know they were there unless you looked inside so let’s take a closer look at these impressive devices.