Someone in the reviews posted test results and found they only had a 253-333mAh capacity at 1.5v (so 0.5Wh). 10440 lithium-ion cells (which closely match AAA size) have 250-350mAh at 3.7v (say, 1.295Wh).
If they actually had the 1200mAh capacity they say they'd have 1.8Wh which is much higher than a straight lithium-ion cell without the charging and voltage regulation circuitry taking up space.
Yeah, this worries me a bit! Never seen any issues, and I'm only using them in low-impact environments (keyboards + mice), and only charging while present.
If they actually had the 1200mAh capacity they say they'd have 1.8Wh which is much higher than a straight lithium-ion cell without the charging and voltage regulation circuitry taking up space.