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August 23, 2011

The Final Solution

Years ago I bought a very fancy universal remote control from the aptly but blandly named Universal Remote Control Inc.. It is computer programmable and controls absolutely every device I have that has infrared input. From the TV to air conditioner, vacuum to lights and everything in between. It works perfectly and I've never found anything that does what it does better. The only down side is that it eats batteries for breakfast, lunch, dinner and several snacks in between. It requires four of those tiny AAA batteries that I've come to hate. An average pair of alkaline batteries might last for about 3 months until the performance was unbearable. Feed it the most expensive Lithium style batteries and it might be happy for 6 months if you push it. Rechargeables you say, well I tried that. You might get a day or two out of a regular set of rechargeable batteries. An Eneloop style battery with a more stable voltage level might get you a week or two, same goes for a rechargeable alkaline. I tried every battery type I could find, nothing improved on buying expensive sets of disposable batteries every few months.

That is until I happened upon a radio control helicopter forum. Not sure why there particularly but someone had mentioned converting some R/C device from AAA batteries to Li-Ion rechargeables. You can actually find Li-Ion batteries in about the same form factor as a standard AAA battery, the only difference being the voltage. Your standard alkaline runs at 1.5V, while the Li-Ion is about 3.7V so you can't just plug in 4 of these Li-Ion in place of the regular alkaline batteries the remote expects. (Well you probably can't, depending on the internal circuitry you might be able to run such a high voltage and it will just work. But without pulling the remote apart to check or risking permanent damage with a test to determine I didn't want to go down that route.) Instead, based on the information I found, I bundled the Li-Ion cells with a "dummy cell". Simply a conductive battery shaped device that has no voltage or really anything and does nothing other than fill the space of a battery. Those dummy cells proved to be the hardest thing to find, it took a couple months to locate some. So I paired up one Li-Ion battery at 3.7V with a spacer, that combination replaces two alkaline batteries at 1.5V so instead of 3V, I have 3.7V. I took a risk on the little extra voltage assuming this wouldn't be harmful and would likely be beneficial since this remote appears to like to operate on higher voltages. Took a bit of a guess on the pairing of the batteries also since it might be possible to end up with 7.4V in place of 3V. But my educated guess said that the remote was likely trying to run off a series of 4 alkaline at 6V so it probably wouldn't matter the ordering. The only issue I encountered was the nub on the Li-Ion battery was bigger than an alkaline and didn't fit in every location, which was easily resolved with some juggling of positions. Well, success! I now have rechargeable batteries working in my remote. They last for months on a charge and work great. Cost worked out to around two times the cost of a single set of non-rechargeable batteries.


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