We had 16 Fizzbooks model NL1 in a Fizzbook trolley which includes 12v power supplies. The school then bought another 14 Fizzbook V3 Model EC10 which are housed in the same cabinet, but I have noticed that the stated power requirements for these Fizzbooks is 19v although they seem to have charged OK (in use for about a year), has anyone else come across this issue?