Eric.
I appreciate your sharing the info as well. It helps all of us to see what is being acheived in the real world.
Jim
--- In electricboats@yahoogroups.com, Dave Kellogg <inganear1@...> wrote:
>
> Eric,
>
> I for one want to thank you for publishing your trials, the data is very useful
> for comparison, one of these days I hope to be able to contribute with my tests.
> Dave K
>
>
>
> ________________________________
> From: Eric <ewdysar@...>
> To: electricboats@yahoogroups.com
> Sent: Mon, March 28, 2011 9:04:35 PM
> Subject: [Electric Boats] Re: Measured performance - more data
>
> Hi everybody,
>
> I did another set of performance trials yesterday. I started at 12:00 noon,
> after the last rain shower passed. The process took about 90 minutes and I
> covered 6.35nm during the tests. I ran the same process as before, 1 pass in
> either direction at a particular throttle setting, progressively climbing
> through 6 settings and then repeat the process descending through the same
> settings until done. There was some wind by the end of the trials, but that
> should be offset through the pass in each direction. The results were more
> consistant than the last trials which had apparent tsunami surge that skewed
> some of the numbers.
>
> Here's this weeks results:
> 495W = 3.0kts
> 1000W = 3.9kts
> 1500W = 4.5kts
> 2450W = 5.0kts
> 3905W = 5.7kts
> 5165W = 5.9kts
>
> Slightly better at the low end and a little worse at the top end, but fairly
> close (+/- 0.2kts) to the previous tests.
>
> Because we had a conversation in the interim about motor temperatures, I
> recorded winding temps during the second half of the trials to see how quickly
> the motor would recover during the lower power settings. With a max observed
> winding temp of 74C at the end of the fourth pass at full throttle, the motor
> dropped to 52C by the end of the last 500W pass.
>
> Right after the trials, I set the throttle to about 2500W and headed out of the
> marina, around the detached breakwater in open seas and then back in. 45
> minutes later, at a constant power setting, the motor was stable at 60C and I
> had covered an additional 3.85nm. Apparently, the speed boost downwind is
> greater than the penalty going upwind resulting in an average speed of just over
> 5.1kts.
>
> After messing about for 30 minutes or so at slower speeds, I brought her back to
> the slip. The entire day was 10.9nm with a 4.0kt average. The battery meter
> showed 107.7Ah consumed. After 15 minutes rest, the battery bank was resting at
> 52.35V. 4 hours on the charger, and she was fully recharged.
>
> In a couple of weeks, I'm going to try a range run on the open ocean at about
> 1400-1500W to see how the batteries match up against their specs. I'm
> predicting about 18nm at 4.3kts out of 6.4kWh of usable capacity, that should
> take a little more than 4 hours.
>
> I know that all this info is more interesting to me, so thank you for your
> time...
>
> Fair winds,
> Eric
> Marina del Rey, CA
>
> --- In electricboats@yahoogroups.com, "Eric" <ewdysar@> wrote:
> >
> > So I finally got a chance to do some controlled performance trials over the
> >weekend. I headed into the main channel of Marina del Rey at about 11:00 AM to
> >measure system data while travelling a 400 yard course in opposite directions.
> >Unfortunately, there appears to have been some residual tsunami surge that
> >skewed some of the runs. From nearly no difference between the 2 runs to 1kt
> >faster speed southbound, 1.4kt faster northbound 10 minutes later and 0.5kt
> >faster southbound 15 minutes after that. So I'll have to repeat the tests
> >sometime in the next few weeks.
> >
> > The boat is a 1964 Bermuda 30 ketch, 8'9" beam, 24' LWL and 10,200#
> >displacement. The conservatively rated 5.5kW electric drive was purchased from
> >Propulsion Marine in Santa Barbara. I assembled my own battery pack from 16
> >Thundersky 160AH LiFePO4 3.2V lithium cells for a pack rating of 8kWh @ 50V
> >nominal.
> >
> > I measured pack voltage, motor RPM, southbound speed and average amperage,
> >northbound speed and average amperage. Then I averaged the results for the 6
> >major speed settings. The pack voltage and current was measured with a E-xpert
> >Pro HV battery monitor, and the speed was measured with a Garmin 60CSx GPS.
> >
> > But here's the quick recap of my boat at 6 different speed settings, 4 runs per
> >setting.
> >
> > 500W = 3kts
> > 1000W = 3.8kts
> > 1475W = 4.3kts
> > 2460W = 5kts
> > 3910W = 5.7kts
> > 5170W = 6kts
> >
> > The funny thing is that my old diesel maxed out around 5.5kts at full
> >throttle. While I don't intend to motor places at 5kw, it's nice to know that
> >I've got the extra power if I get into a tight spot.
> >
> >
> > The system worked great and now I get to re-work my range estimates for the
> >better. This system exceeds my expectations, and I want to thank James for
> >guiding me through the conversion. It has been a real partnership, again more
> >than I expected. The only negative that I can see so far is that the new prop
> >has more prop walk in reverse than the old one, so I've got to spend some time
> >practicing backing down so that it becomes second nature again.
> >
> > That's it for now....
> >
> > Fair winds,
> > Eric
> > Marina del Rey, CA
> >
>
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