You've gone from stating i2pd on Android would use 4TB of data

surely not in 6 hours you dummy! over a month, which network providers use as a billing cycle! my i2p router on my server is up almost a month, and in that time it has had 4 TB traffic, in both directions. so my example 4 TB was not even correct.

I have been running this i2p router for the past 3 or 4 years, yes I do know it! it always has this much traffic. would likely have even more if I had a better upload bandwidth and a higher limit set.
but I have to admit I forgot about the bandwidth limit setting.

how many mAh is the capacity of the external battery?