This is another quick update on my power-bank torture experiment that’s been ongoing since September 2014. Another 50 cycles have been accrued, for a total of 600 since the experiment began, or 615 cycles since the power bank was manufactured. The unit continues to function as expected … the degradation profile doesn’t seem to have changed at all, although the long period of storage at full charge is still quite obvious in the graphs.
A good majority of the readings are hugging the 3350mAh line, where the 80% of initial capacity is represented by ~3100mAh, so we still have some margin until we reach the generally agreed-upon end-of-life for a lithium-polymer cell. Rather surprisingly, it’s not clear what will give way first – will the mechanical connections of the USB ports fail? or will the electronics?
When plotted against a zero-rooted axis, it’s clear that the degradation is not entirely insignificant, although, given that it has now reached 600 cycles which is twice the lower-bound of claimed cycle life (i.e. 300 cycles), it’s surprising that more degradation has not occurred. Again, it’s a case of a watched pot never boiling, so lets keep watching. Experiments continue – the next report will occur once 650 cycles has been accrued.