For SENSOR model (F5J, class 400) we recommend use 7 or 8-cells accus from UNITECH (or our mark UNIBAT).
Here are the results of test UNIBAT and KAN accumulators from Miha HOLC. Miha is expert for electric powered models from Slovenija.

And here is short comment from Miha:

Unitech 1100 cells look like KAN 1050 and weight about the same or a tad more.
For the first 5-7 cycles it is recommended to charge at 1C (1 to 1.1 A) and discharge at 1 Amp.
Delivered capacity at 1 Amp discharging was rising from 1 to 1.1 Ah.
For discharging I used 0.66 Ohm external load on my Schulze ISL8. Batteries were charged with 2 Amps to around 45°C.
From the graph it could be clearly seen, that Unitech 1100 perform much better than KAN under given load. More voltage means more power, more capacity means longer flights.

It is advisable to cool the cells if the load exceeds 15 Amps. Burst load could be in my opinion about 20 Amps. More amps would sag the voltage too much and the controller would probably cut off.

Advice:
Keep the cells warm before the flight! Best used when freshly charged. Cold NiMH cells perform very poorly (voltage and capacitywise).

My personal opinion is that the Unitech 1100 cells have very nice performance/price ratio. Not tested, but presumed, lifespan of the Unitech 1100 would be longer than of KAN 1050 at the same loads.

Miha Holc, Februar 2005