Selecting Cells for UAVs - Sony VTC6 vs Sanyo NCRGA

Introduction 
For the last few years the Sanyo NCR18650GA Lithium Ion cell has been our go-to cell for most flying applications, but after months of testing and customer use cases, we're starting to use the Sony US18650VTC6 cell more and more often. The question we're often asked is: when should you use the NCR-GA, and when should you use the US-VTC6?

Quick Answer
We've got the the full answer and analysis below, but here is the quick answer:
- NCR18650GA is ideal for discharges <20W per cell 
- US18650VTC6 is ideal for discharge >20W per cell

Additional Cell Details
Here is a quick comparison of these two cells:

True / Usable Density
On the surface the GA cell would seem like it would always be a better option that the VTC6 as it has 17% more mAh for the same weight, however, at higher discharge rates (above 20W / 6.5A) we start to see the VTC6 pull ahead in usable Watt Hours:

The reason is simple; heat losses. As the GA cell has a lower C-Rating / higher internal resistance, more of the energy of the cell is consumed by heat during discharge at these higher rates. The GA line drops at discharges above 20W as the test is terminated due to over temperature (testing stops at 60C/140F).

Voltage
As the VTC6 has lower internal resistance it also has a higher average voltage during discharge and a much higher burst voltage a very high discharge rates:



Total Run Time


Conclusion
So, the reign of NCR18650GA is over? Not quite. At lower discharge applications (20W or less) the NCR-GA still has a higher Wh/Kg. It's also less expensive and easier to source and has years of proven performance to support it. Titan will continue to recommend both these cells for their ideal use cases.