The efficiency is a function of the torque. Even if you cut the voltage in half and the torque(amp draw) remains the same the efficiency doesn't change. Thanks. Steve S.
--- In electricboats@yahoogroups.com, "fneilss" <fneilss@...> wrote:
>
> Hey Jeremy,
>
> Thanks for your info.
>
> Regarding oversized motors, I'm trying to figure out how that's good for efficiency at low power settings.
>
> For example, the Mars ME0909 I'm looking at is rated 4.8kw continuous, and 90+% efficiency, but you have to be running at a rate of at least 500 watts to achieve that efficiency. At 250 watts it drops to something like 50%.
>
> I too am looking for high efficiency at low power settings (as low as 100 watts for my new long and skinny build), so I'm curious what motor you're using that runs at such high efficiencies and low power as you report.
>
> Thanks!
>
> Neil S.
>
> --- In electricboats@yahoogroups.com, "Jeremy" <jeremy_harris_uk@> wrote:
> > Overall it's pretty close, although my total system efficiency is better than 50%; I have a prop efficiency of just under 86% (measured), a motor efficiency of 91% at cruise (it's massively oversized - I'm using a 2.8kW rated motor and significantly under-running it for low losses)...
>
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