I don’t know about their reliability, but the sheer novelty of recharging them is something else. I’ve only done it once in six months for the cat feeder and i

I don’t know about their reliability, but the sheer novelty of recharging them is something else. I’ve only done it once in six months for the cat feeder and it hadn’t run out. No fires yet. Presumably the danger would be in the wiring and power electronics. I’d guess the battery is off the shelf, though I haven’t torn one down—they aren’t exactly cheap. My favorite part is the action on opening the end. It is slightly spring loaded, but also limited, it won’t come apart. Someone clever designed it. They have other standard sizes as well, but I haven’t tried them.