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Emax LS2207 2550kv
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A new option in the Lite Spec series from Emax.

Check out the full list of motors in this series here

Summary

Published: Jan 23, 2018 by quadmcfly

Emax LS2207 2550kv

Tested KV:2490kv
Weight:32.9g
Stator W:22mm
Stator H:7mm
Emax has made a name for themselves in the mini-quad community for high performance motors, but up to this point weight has not been a priority in the design constraints.  The Lite Spec series answers the demand for lighter but still high performance motors.  The design trades the machined hardened steel shaft of the RS series motors for a 3mm internal shaft an aluminum prop adapter and opts for the open bell and open bottom approach.  All these weight savings combined shave an impressive amount of weight, allowing the 2207 design to come in lighter than the previous 2306 design, hitting just shy of the 33g mark with my standard ~40mm wire length. This isn't the lightest 2207 on the market by any means, but it definitely falls into a very respectable weight category for the stator size.  It's also worth noting emax uses heavier #18 wire which adds some to the weight, but helps with performance on long wire runs popular with 4-in-1 ESCs.  The LS motors do retain the insanely tight air gap and shaft retaining screw of the RS series designs, though the style of the bell is quite unique with the two-tone black and silver anodizing. Overall a strong new line with some nice features from Emax.

Results

With a complete redesign it is always hard to predict where it will fall in the performance spectrum. Given the focus on this design for weight savings rather than pure performance, and the stated goals of creating a more conservative motor with this design, I was completely blown away by the results here. The power delivery of this motor was on par with some of the most powerful motors on the bench while maintaining efficiency numbers several points lower. The Kv tested at just under 2500kv, coming in a bit lower than expected, but with the motor easily keeping pace with 2600kv motors of similar size the slightly lower Kv clearly isn't hurting it. In addition to impressive thrust, the LS2207 was remarkably quick to get props to stable RPMs, showing a sharp incline and rolloff on acceleration. The high power and lower Kv will definitely show itself in the throttle curve compared to other higher Kv options with similar power, with a sharper rise in thrust near the top of the throttle and lower RPMs at low throttle. Due to the high power output of this motor it should be propped accordingly. While it certainly has the torque to spin heavy 5" props, the current draw quickly becomes unsustainable, especially in a race environment. That being said, at equivalent thrust, this motor is still remarkably efficient even on heavy props if kept out of the last 10-15% of the throttle. Given those factors and combined with the more competitive weight this motor is a very impressive offering from Emax.