Thanks for posting Brett. Those random variations in the raw data are normal. It's usually worse at lower speeds where a gust of wind, boat wake, or a little tidal eddy has a bigger influence.
As for the RPM question, that display shows motor RPM, not prop.
I talked to Scott this morning, sounds like you are "over-propped", that is, too much pitch for your current drive setup. It's hitting the controller's current limit (see PS below) before the motor can get up to full speed. In that condition you'll likely see the motor running a hotter than it should, especially at high power settings. The good news is that the performance numbers look pretty good, and will get even better once it's all dialed-in.
I assume Scott is sending you another pulley to increase the reduction ratio.
Jim
PS. According to Scott, the controller's current limit is set at 100A. While you're only seeing 60A of battery current, the motor current is topping out at 100A. This difference is apparently due to excess circulating current between the motor and controller. Even though Scott has explained this effect to me a dozen times and I still scratch my head. Anyhow, lowering the torque demand on the motor by raising the pulley ratio will allow it to get up to a better RPM where it will run cooler and more efficiently. It will also be able to pull more amps from the batteries since that excess circulating current won't push the controller into it's current limit mode prematurely as it is doing now. The end result is more power and a cooler running motor.
--- In electricboats@yahoogroups.com, "Myles Twete" <matwete@...> wrote:
>
> Or for that matter, what's going on from 25-35amps also. In each case, the
> RPMs increase, yet the speed decreases.
>
> Higher current = higher torque. Higher RPM resulted, yet the speed
> decreased in each of these cases.
>
> Folks: Be sure to take static and multiple measurements to ensure some level
> of accuracy. Also, if wind or current are factors, take readings going
> different directions.
>
> -mt
>
>
>
> From: electricboats@yahoogroups.com [mailto:electricboats@yahoogroups.com]
> On Behalf Of acsarfkram
> Sent: Wednesday, April 13, 2011 9:39 AM
> To: electricboats@yahoogroups.com
> Subject: [Electric Boats] Re: Here are those numbers I promised on my new
> install and performance so far
>
>
>
>
>
> Looking good Brett. I wonder what's going on from 10 to 15 amps?
>
> Mark
> Santa Cruz
>
> --- In electricboats@yahoogroups.com
> <mailto:electricboats%40yahoogroups.com> , "Pastor Brett" <pb@> wrote:
> >
> > Here it is with knots added:
> >
> >
> >
> > Amps MPH Range RPMs Volts Hours Knots
> >
> > 5 2.6 98.8 570 51 38 2.262
> >
> > 10 4 68 760 50 17 3.48
> >
> > 15 3.9 42.9 860 50 11 3.393
> >
> > 20 4.7 36.19 940 49 7.7 4.089
> >
> > 25 5.6 34.16 1060 49 6.1 4.872
> >
> > 35 5.2 22.36 1150 49 4.3 4.524
> >
> > 50 6 17.4 1280 49 2.9 5.22
> >
> > 62 6.5 14.95 1390 49 2.3 5.655
> >
> >
> >
> >
> >
> > Blessings,
> >
> >
> >
> > Pastor Brett
> >
>
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