You'd need a new sort of AA battery; rechargeable nickel chemistries are a bit finicky and they are usually not charged faster than 1C, similar to the rate of l

You'd need a new sort of AA battery; rechargeable nickel chemistries are a bit finicky and they are usually not charged faster than 1C, similar to the rate of lithium chemistries. It is also bad for NiMH batteries to charge them constantly at those voltages; typical recommendations are to avoid "steady-state" charging them at rates faster than 1/40 - 1/20C [1] [1]: http://batteryuniversity.com/learn/article/charging_nickel_metal_hydride http://batteryuniversity.com/learn/article/charging_nickel_m... Lithium-hybrid supercapacitors are often rated for 10C charge/discharge without the low cycle limits or volatility of lithium batteries, but they are a young technology and it looks like commercial options are currently very expensive with capacities in the 1-10mAh range @ 2.3-2.8V.