EMAX E3 Series 2207 1900KV

The EMAX E3 Series 2207 1900KV is a brushless FPV outrunner for 5-inch quadcopters, intended for freestyle and racing on 3 to 6S. EMAX is a Chinese maker of model-flying and FPV drive components. The motor has 12 slots and 14 poles (12N14P).

The 2207 stator measures 22 mm in diameter and 7 mm in height, and the case is 28.6 mm in outer diameter and 32.8 mm high. At 1,900 KV that gives a no-load speed of roughly 42,200 rpm on 6S (22.2 V nominal). The weight of 31.6 g is without the silicone lead. The maker quotes up to 50 A and 1,260 W, both as 6S values; 50 A at 25.2 V, the voltage of a fully charged 6S pack, gives exactly 1,260 W. These are peak values, not a continuous load.

The range of 3 to 6S means that cell count changes the character of the motor: on 4S the voltage is two thirds of the 6S value, and the no-load speed falls in the same proportion. Motor, speed controller (ESC) and battery must carry the same cell count, and the controller needs headroom above the 50 A. Power figures are compared only on the same time basis; makers use 3 to 180 s. For flying, the whole machine counts: operator registration from 250 g or with a camera, EU class by take-off mass.

A 5-inch drive is handled roughly in freestyle flying. The things to check are the true running of the shaft after ground contact, the bearings for roughness and play, and the mounting screws for a firm seat. Silicone leads are flexible but sensitive to chafing on the frame and to heat at solder joints. Overload shows in discoloured varnish on the winding; with a shorted turn the motor runs unevenly and draws extra current.