And it’s not even close to empty: this is a JeeNode USB with a 1300 mAh LiPo battery tied to its back, and (as I just measured) it’s still running at 3.74 V, go figure.
Let’s do the math on what’s going on here:
- the battery is specified as 1300 mAh, i.e. 1300 mA for one hour and then it’s empty
- in this case, it has been running for some 1096 x 24 = 26,304 hours total
- so the average current consumption must have been under 1300 / 26304 = 50 µA
- well… in that case, the battery should be empty by now, but it isn’t
- in fact, I suspect that the average power consumption is more like 10..25 µA
Two things to note: 1) LiPo batteries pack a lot of energy, and 2) they have a really low self-discharge rate, so they are able to store that energy for a long time.