The HEQ5 Pro draws only a little less than the EQ6 Pro. If you design for an EQ6/NEQ6 Pro, you'll have your HEQ5 Pro covered.
I measured EQ6 Pro power draw some time ago and found:
- Sidereal Tracking = 11W
- Max. Slew Rate = 22W
Here are a couple of related threads:
Batteries
EQ6 Power Cable