Just a thought... I bought a 35 amp/hr deep cycle battery at a low cost store for about $22. It will run the K2 without need for recharge for a VERY long time, maybe 48 hours of continuous contest style use, or a month of casual use. Recharging by any of many methods is simple. Won't carry it with you, but for home use, nothing could be quieter, and very little cheaper. 72 Fred K2 # 700