changing controllers

Hi everyone I am purchasing ZENN 1 EV LSV Has a Curtis 1236e-64xx Zenn is a 72 VDC if I hook up a generator as range extender by hooking up a homemade ac/dc battery charger the bulk voltage would be 1.2 X Nominal Battery Voltage so in this case 86.4 VDC is that going to cause problems or is...