it is the 400hz issue vs 60 hz. Aircraft use 400hz, as the alternators can be smaller, (lighter) but the associated output is then subject to wide fluxuations in output.
The power at 400hz, when the voltage fluxuates, the reactive drops through the system are even more significant, up to 7 times the difference. Typical chargers are not set up to handle this voltage swing, especially the drops.
The batteries are then subject to this flux, and it degrades them in respect to 60hz charging.
Not to be flippant. In regards to battery degradation, not certain of the duration of flight/charge that your airline experiences. Did you experience the need to charge devices inflight very often?
Last edited by underfire; 21st June 2017 at 06:34.