[MetalMan]

Why do you want to do it that way? 20 cells to a single Wanderer XL motor like a 10XL would be a very powerful setup, and would be well within the specs of even a 9920. 20 cells total would not be enough to supply dual Lehner 2800s, unless you did 10 cells to each motor. You could run 28 cells total, 14 to each motor, though.

Overrevving motors is not a good practice, and in the case of the Lehner 2800XL, 2800 is the loaded kv. You can assume that the unloaded kv would be about 200 higher, so unloaded with the full battery voltage would yield a RPM of about 72,000, which is much too high. At that point you risk damaging the motor by way of the magnet coming loose. It's also possible that the bearings would seize, causing a huge current to be pulled by the motor(s), which could kill a controller (potentially).