RE: hobbico mkII and li-poly?
To start, the Hobbico MKII field charger does not give a full charge on LiPos. It was designed to charge old generation Li Ion cells and packs which are charged @ 4.1v per cell. Hence a 2S LiPo pack reading 8.2v fresh off the charger. Today's LiPos are fully charged from 4.2-4.235v per cell.
No worries - this doesnt mean the MKII will not charge LiPos. It does an excellent job, but only charges your packs to about 85-90%. More modern LiPo chargers will give 95-100% charges. The good news is, this isnt a huge drop in flight time and power, and its hard to beat the $50 price tag on the MKI!!
Kevin -
What motor do you have on your IFO? Anything bigger than 280 would be a problem. The TP860 cells can handle 5C max current - that is around 4.3 amps max continuous, with short 5-15 second bursts to 6.8 amps.
If your motor is pulling more than 4-7 amps, the cells are dropping in voltage under load to a point of 3V per cell (where your ESC cuts in). This is typical anywhere people use cells that are too small for a given motor.
The newest Thunder Power 830s can handle 8-10C continuous. I fly them in GWS powered models pulling 7-10 amps at full throttle and the packs work excellent. However, if I put one of my older 860 packs in, the ESC will also shut the motor off after a minute or so.
Let us know what motor, gearing and prop youve got. That way we'll know if youre pulling too much current from those cells and causing the premature shut down. Dont set the cut off any lower - it will work if you do this, but you will be killing the cells pretty quickly.
Also, is the battery cold when you are flying? If your motor isnt pulling too much current, then a cold battery might be the problem. Anything under 70 degrees and I notice packs put out much less voltage. To remedy this, I'll keep my packs in the car or warm while they charge.