Friday, February 12, 2016
Finding a Replacement For Mercury Batteries
The good news is that there are a couple of alternatives that work pretty well.
Wein Cells are zinc-air replacements that come in several different common sizes. They don't last as long as alkalines, but they register the correct voltage for most of the battery life (maybe two months or so) before slowly dropping off. Since zinc-air batteries don't start working until you pull the tab off of them (the tab blocks exposure to air, stopping the chemical reaction), you can buy several and have them on hand for when the current one goes dead. Once you pull that tab off, they will self-discharge whether you're using them or not. You can replace the tab (or use a piece of tape or something) to cover the air holes when you know you won't be using them for a while, slowing or stopping the self discharge. The down side to Wein Cells is the relatively short lifespan and high price. $4.50 for a battery that lasts two months isn't terrible, but it's still a repeating cost.
Finally, the most expensive (but probably the easiest and maybe the longest lasting) option is to buy a voltage-dropping adapter for about $40 that allows you to use a standard, readily-available silver oxide battery. Alkalines fit the adaptor as well and they'll register the correct voltage with the adaptor, but there's still the issue of the discharge curve. Silver Oxide batteries are preferable for this reason.