RE: Hacker A30-12L vs Turnigy SK3 3542-1000Kv -Head to Head PERFORMANCE TEST
<span style="font-size: medium">Discussion of these results:
</span>1. The results showed this motor has a Kv of 977 RPM/V, slightly lower than Retailer quoted Kv of 1000 RPM/V -but only by a small amount.
We can immediately see that the Kv must be lower than 1000, from the No-Load testing. The motor had an RPM of 16051 when driven by a voltage of 16.66V. If the Kv was 1000, then the No-Load RPM would be expected to be 16,660 (i.e. 16.66V x 1000 RPM/V).
However, Kv is only a theoretical value, calculated as if the motor was perfect with no losses. In reality, all electric motors have losses due to voltage drop across Rm and also due to thermal losses. The "real world no load speed" is a much more practical value, and was calculated by DriveCalc as 962 RPM/V.</p>
2. The No-Load current for this motor was between 2.8A and 3.5A -this is substantially higher than the Retailer spec of 1.8A. The Rm & Rd were found to be 58milliohms, almost 2-fold higher than the Hacker spec of 30 milliohms.</p>
3. The most striking feature of this motor test is that when 4S LiPo was used as the voltage driving source, <span style="font-size: small">ALL props from 11x4.7 and larger, exceeded the max current rating of 50A. And EVERY SINGLE PROP -even the small 10x5 one – exceeded the 500W max power rating.</span> Indeed, the 14x8.5 prop needed 1016W of power, at a current of 77.6A.</p>
4. Despite greatly overstepping the max current and power specs, the motor continued to function well at these very high levels, at least for short periods. It was noticeable that with the largest props, the current and RPM “sagged downward” from an initial peak, and settled at a steady state lower level after ~30 secs. This did NOT happen with the smaller props used. It seems very likely that this current and RPM “sagging down” is a sign that the motor was probably overloaded, certainly with the 15x8 prop.
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