General rule with NiMH's is to not discharge them fully (no less than 0.9V per cell), and store them with a partial charge (say, 1000mAh).
Charge on the day if you can, if not the night before is fine. Re-peaking on the day can be a shade risky because you might overcharge the cells.
NiMH's biggest problem (especially with the more race oriented cells, although Orion's rocket packs aren't usually race cells) is self discharge. It can kill the cells if stored unused for long periods (months), and even during short term storage (weeks) between race meetings it can put the cells out of balance. This is why equalisers were such a common accessory in the NiMH days.
There is only one equaliser that I know of for stick packs, and that is/was made by Much-More. It required cutting holes in the heatshrink in the side of the pack.
An alternative way of equalising is to put the cells on a trickle charge at 0.1C for 12-14hrs, this will top up all the cells to an equal level.
|