Why are Energizer “D” batteries so weak? To find out the answer, I decided to take one apart and see what was inside. As this picture reveals, inside the “D” battery is a much smaller battery! The Energizer “D” battery is actually just a cheap plastic shell surrounding a much smaller, low-capacity battery similar in size and capacity to an “AA” battery (2500 mAh).

This explains why the Energizer “D” rechargeable battery has such low power capacity to begin with. The company doesn’t even try to make it a high-capacity “D” battery, it seems. They’re filling part of the inside of the battery body with nothing more than cheap plastic and useless air. And how much does Energizer charge for this “D” battery? More than $12 each!

It’s true: These inferior “D” batteries cost around $25 for a pack of two. These are known as “Energizer E2 Rechargeable Batteries, Size D,” rated at 2500 mAh each. (mAh is a measure of how much power is contained in the battery. It’s sort of like the fuel tank in your car. The bigger the number, the more power the battery delivers.)

By comparison, an Energizer AA battery rated at the exact same capacity — 2500 mAh — costs about THREE dollars!

Found by ECA.