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

Tuesday, March 15, 2011

[Electric Boats] Re: Measured performance

Hi Eric,

Thanks for those numbers. I have been trying to tweak throttle settings using the Watt Meter at the helm and have found rather small drop in amp draw can allow the pack to rebound noticeably with no negative impact on boat speed.

What is your pack voltage fully charged?

Mark
Santa Cruz

--- In electricboats@yahoogroups.com, "Eric" <ewdysar@...> wrote:
>
> Mark,
>
> I worked my way up through the power settings up to the top speed setting and then repeated the runs back down through the power settings. So all of the 5kW runs were in the middle of the exercise. Since I finished the day with the pack at about 50% of usable capacity or 40% DoD, these high amp runs were probably at about 20% DoD.
>
> My pack voltage under a 106A load was 48.8-48.7V. When I dropped the power setting to 79.4A, the pack rebounded to 49.5V, and was back up to 52.2V by the time I finished the last 9.4A run.
>
> After the next time I do the exercise (under more consistant conditions), I'll post the spreadsheet with my collected data.
>
> Thanks for the encouragement.
>
> Fair winds,
> Eric
> Marina del Rey, CA
>
> --- In electricboats@yahoogroups.com, "acsarfkram" <acsarfkram@> wrote:
> >
> > Hi Eric,
> >
> > Those are excellent numbers! Do you remember what the voltage dropped to at 5170 watts?
> >
> > Mark
> > Santa Cruz
> > Not that anyone asked :-)...Lotus Flower survived the tsunami.
> >
> > --- In electricboats@yahoogroups.com, "Eric" <ewdysar@> wrote:
> > >
> > > So I finally got a chance to do some controlled performance trials over the weekend....
> > >
> > > ... 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....
> > >
> > > ... 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
> > >
> > > That's it for now....
> > >
> > > Fair winds,
> > > Eric
> > > Marina del Rey, CA
> > >
> >
>