Ok so i figured out my mistake. 10 amps x 72 volts is 720 watts x 6 hours of charging = 4320 watts.
Ok that makes alot more sence. So my Victron system will charge my E bike in its current configuration. 2 300 ah batteries in series is 7200 watts so will a 24 1200 VA inverter charge that for that long even though its only 1000 watts?