HI Greg,

The limiting factor the the upper end of the voltage range is the threshold at which the transient suppression begins to conduct, which will have a very wide tolerance.  This topic was discussed in the other forum a while back, here:
main@ap-ug.groups.io | Max Voltage Question got Mach2GTO/GTOCP5

The general consensus on that thread seemed to be that having a CP5 powered directly by a battery that is also being charged was discouraged. 

Cheers,
Mike Hanson