(Written by Watson “Watt Sun” Apr 24, ’05 – this was long before you could buy a cheap LED flashlight at the corner store.)
When I first started making my white LED flashlights, I made some with four cell battery holders because I couldn’t get any three cell holders. Also I bought several regular 4 AA cell flashlights and converted the lamp to three LEDs. In both cases, I made a dummy battery to replace the fourth cell, so they would run on three alkaline cells or 4.5V. The dummy battery in many cases was a piece of half inch wood dowel with screws in each end and a shorting wire between. I also made them from a 6-32 screw 2″ long with nylon washers on the ends.
Later, I got this ‘brilliant’ idea that I could save money by replacing the three AA alkalines with four Ni-MH rechargeable cells. So I removed the dummy cell and put four cheapo AA Ni-MH cells in their place. These generally cost under ten dollars for four cells, sometimes less if I bought them with a charger on sale. Many of the sets of four AAs were from my digital camera, for which I buy a new set every year or less after a dozen or two recharges. I just figure that it’s prudent to keep a fresh set or two in the camera, and use the older sets for the flashlights.
I left several of these flashlights around the house in areas like the closet or cupboards to take a quick look in the dark corners. They stay there for weeks at a time without getting used, with a minute or two use on occasion. I’ve noticed that they all suffer from the one bugaboo of rechargeables, the loss of capacity over a few months’ time. I recharge them every few months and even though they get used little, they need a recharge a few months later. And it’s plainly obvious: they put out little light when they get discharged.
I could go back to the three alkalines without any problem. This would save having to recharge them every few months. One reason I hesitate to do this is because I’ve found that the alkalines often leak when stored a long time, especially during the warm summer months. I’ve never had a Ni-MH leak, but I’m not saying it can’t happen. So I’m trading the inconvenience of having to recharge for the reduction of damage to the flashlights.
I’ve purchased some plastic battery storage boxes to hold the spare sets of AA cells once they’re recharged. I’ve had to tape a label on the front to write the recharge date, so I know when it’s time to recharge them after a few months. If I don’t, then I end up with almost dead batteries more often than not.