|Kokam Cell Pro Range of Batteries & Accessories|
When you do your model flying on a tight budget, you can’t always afford top quality items. As a result, you sometimes find that expensive items get put into storage awaiting the opportunity to get the things they need to go with them.
One such case with me was a result of a couple of purchases made a while back when I got a couple of bargains on Ebay, one a Protech Unlimited electric glider and the other a lovely Balsacraft Hurricane. As funds were available at the time, I decided to buy a quality brushless motor and ESC for the Hurricane. The Unlimited I tried with a geared 600 and a direct drive 650, but neither was satisfactory. Then I crashed the Hurricane, and decided to try the Motor in the Unlimited, but due to the limited battery space (which only allows 7 cells) in the Unlimited and the motor was designed for 8-10 cells, this experiment failed. So the model was put to one side. A year passed, and the model remained on the sidelines but new battery technologies were improving and prices coming down. Then I had a real stroke of fortune, which resulted in some superb items coming my way. The items were a high quality Lithium battery and the items needed to maintain it, a combination charger/ balancer and a discharge protection module. My Unlimited was airborne again!
The items in question are a 3200mah 3s1p Kokam Cell Pro battery, a Cell pro 4s charger balancer and a Cell pro 4s Discharge Protection module. The module costs £28.20, well worth the price when a top quality battery like the Cell pro one costs £111.62 By using the Cell pro products, the battery should last a great deal longer than cheaper rivals. This cell has also proved itself at the highest level of competition.
The motor I originally bought for the Hurricane is a Mega Motors 22/20/4, and as this was originally intended for use with 8 cells, a Jeti 40 amp esc. The Puffin web site does not quote figures for a 3 cell lipo, but does say that for 10 cells NiMH use a 10x6 prop, which is what I fitted.
Before a maiden flight, the combination was tested on a wattmeter and showed 384Watts, at 10.2 volts and 38.2 amps. This is very close to the 40 amp ESC’s limits, but I decided to give it a try anyway. The ESC showed no signs of stress, did not get hot or cut out. Short power runs in an electric glider, which spends much of it’s time unpowered, would appear to be acceptable. But I do plan to get a more suitable ESC, however.
The Battery is a 3200mah 3s1p pack, and with a continuous 20c rating, this is not even stretched by the 38 amp drain of the Mega. As this combination will propel the model out of sight in about 45 seconds, motor runs tend to be fairly short. And even when there is no thermal or slope lift available, at this time of year cold hands are the limiting factor as to how long one can stay aloft.
The Battery showed 3.4v/ cell under the maximum load the motor was capable of pulling and was extremely comfortable at this level of effort, with no detectable heat gain, although this was only a fingertip test. But with the associated gear that I also use, the long term prospects are very good that this battery will last a very long time indeed. And with the added benefit that with another speed controller and motor, there is far more to come from this battery. In theory at least, this battery should be capable of producing 500 watts and more.
Discharge Protection Module
So without one of these units it is not safe to land a model, switch off and then fly again. With the module in place, this is perfectly safe to do. In fact in an effort to test this unit I landed after some use and then flew again, but it was getting dark before the BEC cut in, with the battery still showing 3.4v/cell, well above the cutoff. But I have complete faith that this unit will perform as specified, and will again enhance the prospects of the battery lasting a long time. The one disadvantage I found with this unit was that with this particular model, in order to plug the battery into the unit and remove it again the wings had to be removed, but this was a minor inconvenience.
In fact the makers say that with the use of the charger and DPM, the battery should last 500 cycles. This is by far the best prediction I have ever heard of for a battery, and in my opinion totally justifies the initial price, which is somewhat higher than rival products.
In conclusion, the Cell Pro products are excellent value for money, the highest quality products I have seen or have heard of. I recommend them fully and intend to buy them again myself.
Cell Pro & other Aurorra products are available to buy online at:
108 Wheel Lane,
Sheffield S35 8RY
Tel: 0114 2570401