Warwick-Those cells are made by KoKam but are not the Orion cells. They are of a smaller capacity than we use (only 750mA-h) and are produced as samples, for testing, that might be used in a custom application. I studied the graph and had some communication with Ling. On the Y axis is the energy epended on a discharge which is related to capacity. The striking result is that the cells charged at 1C are represented by the lines that don't drop very much as we go to the right. This means they have little loss in energy output with each additional cycle even at high discharge rates. They achieve upwards of 400 cycles. The lines representing cells charged at 2C drop steeply. You can see the little steps as each discharge cycle reduces the output of the cell. They tend to end at 125 cycles or so. The battery can be considered dead or unusable where the line ends. At least the testing stopped there.
1C for my roughly 5000 mA-h cells is 5 amps. 2C would be 10 A charge rate.
I have personal experience with Apoggee Lithium Manganeese cells charged at 2C which they recommended. The drop in runtime was very fast. The drop in runtime with a couple of months storage after they were no longer satisfactory in the car was exceptionally fast and complete.
Some of the other cells I have charged at 2C on occasion with much better success. If indeed the charging deteriorates the cell more than the high heat with high discharge rate then it would be worth testing this new battery at 1 C charge rate only to see if it actualy will last longer in high Drain RC car use. I have ordered a third battery charger to effect this.
Interestingly when I first tested the LiPo scorpion pack I posted that probably we would need three batteries and 3 chargers to use these cells effectively. Others proponents of LiPo said no. Is it worth this much expense is the likely question. Well the TC5 looked really good compared to the Nitro's even on the straight last race.
What we don't see on this graph is what is happening to the Voltage. It does no good to really pamper a cell so that it achieves 400 cycles if the voltage is subpar for RC car performance after 50 cycles and requires replacement. It is very possible that Average Voltage and Capacity are lost at similar rates. It is certainly worth a pampering test. These cells have only had 10 amps for about 10 minutes each just for the race.
Last edited by John Stranahan; 10-08-2007 at 05:52 PM.