I came across some Tenavolt rechargeable AA batteries. The batteries actually contain a 13430 3.7v 750mAh 2.78Wh Li-Ion battery and a built-in bms to maintain a constant current of 1.5v. Just thought I'd bring this up for people with locks and such since they behave better at 1.5v rather than 1.2v that NiMH rechargable batteries put out such as the Enloop batteries that are so popular.
Here's an amazon link to the batteries.
Here's a good video of a teardown for the battery.
Here's a good review of the relevant information about the Tenavolt batteries.