depends on the bulb you use and how much lamping you do on any particular night. i run a 30 watt bulb on a 14amp lithium battery. i had 50 rabbits with one dog in one night not so long ago and only used 1 green lights worth of power on the pack, ive also had a night with 71 rabbits and 2 dogs which used 2 green lights on the battery. a 22 amp should last you a night and some i would of thought.