I just bought a BL-5J battery from Amazon (not from one of their other sellers) that appears authentic. The hologram checks out, with the various dots visible from the correct angle and the physical package of the battery also appears correct.

However, the new battery seems to have strange performance characteristics. Specifically, it will show a 100% full battery meter for 8 - 10 hours, then with just a little bit of use (sending and receiving a couple SMS messages) it will drop to empty.

When I view the HAL data, I see this:

lshal | grep reporting
...
battery.reporting.design = 802 (0x322) (int)
...
battery.reporting.unit = 'mAh' (string)

The original battery showed a design value of 1288.

So does this mean that the battery is counterfeit? Does the battery.reporting.design value actually come directly from the battery?

Thanks!