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Old 08-01-2003 | 01:56 PM
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Greg Covey's Avatar
Greg Covey
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Default Li- Poly

tailheavy,

Don't worry about being confused, it is understandable since the Lithium revolution is so new. The fact that you are using Lithium in electric flight means that you are on the cutting edge.

Sometimes, paperwork is wrong and it takes time to correct. The paperwork stating 8C discharge may have reflected the original target but not the production cells for 1200HC. Each cell type is different, even within the same HD catagory.

Lithium cells are now getting several ratings, one is for continuous current delivery and another is for peak short term delivery. Since you use throttle management, you can take advantage of the peak short term rating when picking a cell type or designing your power system.

The 1200HC cell (aka 1200HD) has a continuous current delivery of 5C or 6amps. The peak short term delivery is rated to 8C or 9.6amps. You will find that for short bursts you can exceed the 8C rating without damaging the cells. I often suggest an 8C-10C range for short term bursts on the 1200HC cell, hence the 6-12amp capability.

The even newer 1500HD cells, just hitting the market, deliver a continuous 6C current or 6*1500 = 9000mA or 9amps. Again, the peak current delivery is 8-10C or 12-15amps. This is an impressive cell.

Super high current packs can be made from smaller cells but the cost usually goes up. Look at the Bishop Power Products site. They make super high current packs from the smaller Kokam 340SHD cells that can deliver up to an amazing 20C! A 3s3p configuration like the Kokam 1020SHC 11.1v pack for $99.95 can deliver 20amps in a 3oz package. Compare that to an equivalent 10-cell 2/3A 1000mAh HECELL NiMH pack at 7.3oz that can only deliver 16amps and you can see why the Lithium revolution is so exciting to the world of e-flight!