You'll Never Guess What's Inside This "D" Battery

I'm growing more and more addicted to rechargeable batteries instead of alkalines, thanks to all the wireless game controllers and other toys rapidly filling up my house. They work well and are infinitely more cost effective than alkaline cells; I keep a charger stocked with four cells right next to the Wii. But so far I've only made the switch with AA batteries.

Rechargeables come in all shapes and sizes, of course, and Mike Adams snagged a "D"-size Energizer battery, which you'd think would offer a substantial amount of energy since it's so large in size. Yet oddly, he found the battery's capacity, noted right there on the side of the cell, to be the same 2,500mAh that AA batteries offer. And yet a "D" cell is four or five times the size of a AA. What gives?

Adams cracked open the battery to find a surprising reality: Inside he found not a giant cell but rather a plastic shell wrapped around a tiny battery, about the size of a AA. Mystery solved.

Maybe the design of these rechargeables doesn't allow for larger cells, you might ask, and that this design is imperfect, but still a necessity? Why then do the rechargeable "D" batteries cost $12 vs. $3 for the AA ones? Hmmm.

Rest assured, as Adams points out, high-capacity, rechargeable "D" cells do exist. The bottom line: When shopping for rechargeable cells, remember to look at the mAh rating, which reflects how long they'll last. Don't get suckered by paying a lot for a cheap, plastic shell!