I've been impressed by the "new/newer" Nickel metal hydride batteries. I bought a 5 unit cordless Panasonic phone system about 10 plus years ago and it still has the original nickel batteries in it. Each handset has just two AAA cells. BK-40AAABU. They have been on the chargers continuously and are still very functional. I rotate between two units. Charge one at night switch, charge the other during the day, the rest stay on the cradle. They still last a good day or two on a single charge, as they did when new. The lithium I had before, lasted five years, at best, if I removed them from the charger when full. If I left them on the charger they died in a year.
I bought an Eveready system and batteries from Costco over five years ago, Ni-MH, and put them in a blood pressure tester over a year ago. They haven't yet needed a recharge. The 4 AA nickel batteries replaced 4 alkaline Evereadys. I thought I'd have to recharge them every month. But haven't in over a year. It laid unused for half a year and is only used once or twice a week lately. Still going strong.
I put four of those AA's into a Costco Eveready flashlight that is supposed to have four C-Cells. That flashlight,1000 lumens, run usually at half brightness, will last about a day running continuously when fully charged. I recharge them every two to three months or longer. It sits on the counter for days even weeks between uses sometimes, and often used daily.
Seems a very good record for very puny batteries. Maybe they could be applied for home and vehicle "safe" use? I never heard of one being on fire?
