G'day PCars,
Some AC powered devices, such as ones with small motors, are frequency sensitive and probably wouldn't run well, if at all, on a 400Hz supply.
Battery chargers are another story, they convert AC to DC to charge the battery in the device and so the incoming AC frequency is irrelevant as the output DC frequency is by definition zero. Most modern battery chargers can sort out the input voltage in order to output the correct DC voltage.
I've run a laptop from the aircraft supply, through a charger, without any problems though something like a directly powered electric shaver might be problematic.
Regards,
BH.