I know I am (very) late to the party, but...
A few years ago, the AA Power Functions battery packs was replaced with a new model.
The old model (58119, top) had a weak, yellowish green LED, while the newer one (16511, bottom) has a brighter pure green LED.
After opening, you see that the PCB seems to miss the protection device, a resettable fuse (rectangle marked HL5L). This conducted several people to think that the protection, which cuts power at a current above 750mA, had been removed, and that the new battery pack was more suited for high power models.
But if you look at the bottom of the battery pack, you see that there is a wired protection, inserted in a hole of the case.
...and the rating of this resettable fuse is just the same as previous one, 750mA. So no luck with power-hog models! Note that the different technology might slightly impact the behaviour (more or less thermal dissipation/conduction).