Electronics engineer Bogdan "Electro Bob" Raducanu has penned a passionate plea to anyone making compact battery-powered sensors and other remote devices — to abandon the ubiquitous coin cell power source.
"If you can make a sensor microscopic — fine. If it needs to be portable — fine. But if it is rather small but still visible you are not doing anyone any favor by making it as small as possible with a coin cell battery that runs just a few months or even less," Raducanu begins. "If your sensor can run for years and years on a pair of AA batteries, by all means use these! I want either a microscopic sensor – so small that I don't see it — or one with a battery that lasts forever."
Raducanu's arguments against the common coin cell are many, without even touching upon their tendency to wind up being swallowed by curious children should they find their way out of the device in which they were installed: their small energy capacity, with common CR2032 cells offering 14 times less capacity than a pair of AAs; their awkwardness in handling and installation; the incredible variety of diameters and thicknesses making it difficult to find the right size required; and their relatively high cost.
"This sensor can sense if a window or door is open or closed," Raducanu writes of one example. "On the left: A commercial sensor operating on a CR2032 coin cell. On the right: My DIY sensor running on 2× AAA [batteries] for five times more battery life. Both are in the size region where they will be visible on the door/window frame but are not intrusive. The one with the bigger battery is way more comfortable to use, since its battery has to be replaced five times less often."
Other examples include a motion sensor, this time powered on a pair of AA-sized batteries, and a trio of remote controls — a AAA-based version of which is barely larger than the CR2032-based version, but offering a noticeably longer battery life.
"The middle ground is crap. It’s still big enough that I see it and bothers me and has short enough battery life that bothers me," Raducanu says. "Why would I want to have a slightly smaller sensor with much much less battery life? Do you think I like having 50 sensors/remotes/etc. with six months of battery life in my house such that every 1-2 days something stops working because of a low battery? Of course I don't!"
Raducanu's full plea is available on the Electro Bob website.