nimh deffenetly isnt' the tecnology today, but they still arn't 8tracks of battery's.. YET.
i have 2 packs of custom AA cells, 2500's. one is going strong.. always taking 2200mah each charge. the other.. not so good. 300-400 mah. junk.
you can't over-discharge nimh or nicd. they say .9v a cell. so on a hump pack, thats 4.5 volts.
if your battery is 1000mah.. 1amp.
1500mah... 1.5amp.
2000mah, 2amps. so on. less is always better. but always charge before your race, if not possible.. night before.
nimh and nicd discharge overnight on their own.. they won't last on the shelf forever. the more times you don't run the hump pack down to 4.5, say charge on the go.. 1/2 charges.. yoru hurting the memory in the cells.
lipo is the ticket. even lifepo4's.. but they have their rules as well.
nimh/nicd don't last forever.. you might need to buy a new pack. good luck.