T-Pain Is On A Boat: [Electric Boats] Re: conversion performance

Hi tkgc9,

I apologize if I offended you before, even though I did originally thank you for your post. The request for watts was a reminder for everyone here, not a personal attack. In this group, over the years, many people have posted performance results and we have found that watts are a universal value that allows comparison between virtually any conversion. I think that it has been a while since I posted my boat's performance, so here are some messages from the past...

Thank you again for being a valuable member of this community.

Fair winds and smooth seas,

Eric

Marina del Rey, CA

July 7, 2013

Just because it's come up in conversation, here are my previous three posts concerning the measured performance of my conversion. The earlier posts describe the process and the instruments used to collect the data.

I used a GPS for accuracy, the Signet analog knot meter on my old boat occasionally reads with 5% of corrected GPS speed, but it's usually just a rough estimate. Using the GPS in calm conditions in opposing directions will correct out any current or wind. To point, the first session had Tsunami surge rolling through the marina, with currents of plus and minus 1-2kts, but the overall results match testing done at slack tide. The variances average out.

Fair winds,
Eric

--- In electricboats@yahoogroups.com, "Eric" <ewdysar@...> wrote:> April 4, 2013> Last weekend I realized that it had been about 2 years since my last performance test, and I wondered if anything had changed over time. I was at the marina on Easter morning and the conditions appeared to be ideal for another performance test. I ran through the same process listed below in about 100 minutes, covering a little over 7nm in total.
>
> Here's this weeks results:
> 497W = 3.1kts
> 1000W = 4.0kts
> 1500W = 4.5kts
> 2500W = 5.2kts
> 3975W = 5.7kts
> 5000W = 5.9kts
>
> So there have been pretty minor changes, well within testing errors. Like before, the max winding temp was 72C and that temperature had dropped to 53C by the end of the last slow speed pass. 2 years later, the drive, prop, hull, batteries, etc. seem to delivering consistent performance.
>
> If I average the three different testing sessions, the numbers look like this...
>
> Here's the overall average results:
> 499W = 3.0kts
> 1000W = 3.9kts
> 1500W = 4.4kts
> 2470W = 5.0kts
> 3935W = 5.7kts
> 5115W = 5.9kts
>
> This data collectively represents more than 3nm at each speed, in calm conditions, in multiple directions.
>
> On another note, I did a full throttle run at the dock. Average amp draw was 158.8A DC at 47.24V or 7.5kW! Compare that to the 5.1kW noted above at full throttle in open water. Since I was starting with 80Ah already used of my 128Ah of usable capacity, the 160A load was rapidly draining my battery pack. After more than 5 minutes at full throttle, the motor windings had climbed to 85C, well under the manufacturer's rated limit of 150C, although the temp had not stabilized yet. I decided to stop the experiment as I quickly approached having only 30% of my usable capacity left and I didn't have too much time to get some electrons back into the pack before I had to leave. Perhaps I can do this again with a fully charged pack to see where the ME0913 motor temps will stabilize while pulling 7.5kW in the bilge of my boat. In spite of what some of the component vendors might say, I'm pretty sure that running that motor in boat at 10.5kW will cause it to overheat in relatively short order. I appreciate that my vendor conservatively rated my entire drive system, I'm sure that it will continue to perform well for many years.
>
> Anyway, I collected the data and I thought that some people here might find it interesting...
>
> Fair winds and smooth seas,
> Eric
> 1964 Bermuda 30 ketch, 5.5kW Propulsion Marine drive, 8kWh lithium batteries
> Marina del Rey, CA
>
> --- In electricboats@yahoogroups.com, "Eric" <ewdysar@> wrote:> > March 28, 2011> > 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:
> > > March 14, 2011
> > > 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
> > >
> >
>