mCX LiPo problems please help!!!
 

Both the stock LiPo batteries from my mCX are dying and I need help. I soldered a 6 volt AC power supply to the charger and charged up one of the batteries. After the light stayed off for 25+ seconds, I took it off and measured it. it said it was at 4.20 volts so I flew it. It lasted about 5 minutes (110mAH) i think i should be getting more runtime. when the heli's light blinked and cut throttle, i unplugged it and the battery measured at 3.74 volts. I thought they were supposed to go down to more like 3.0 volts. Does anyone know why this is? do I need a new electronics board on my mCX or just new batteries? oh, and with 4 AA batteries in the charger the mCX batteries lasted 30 seconds at the most.