going with a 2500mAh pack would be a mistake... what is your voltage coming off the track right now?

I really wouldn't bother discharging my packs if the voltage is anything below 4.0V, there is a balancing act between depth of discharge and temperature where you might be fretting over something that is almost irrelevant if you are subjecting your packs to any significant amount of heat, more info here:
https://batteryuniversity.com/learn/...ased_batteries