Hi JBWrights,
Mark is right on with his comments. Definately use a BMS for your cells, there are some cheaper ones that cost about $15/cell which is reasonable for the number of cells that we're running in 48V systems.
I agree that wind generators can be a big pain on a small boat, you might want to delay that "upgrade" for a little while after you get your boat going so that you can determine how desperately you need it. I agree that you will get very little energy from regen, maybe not even enough to handle your house needs. Your short waterline really makes that harder.
My Bermuda 30 ketch has no good places for solar, so my solution for off-the-grid charging is a Yamaha 2000 generator. At 50 pounds that is easily taken ashore for day sails, it's a modular solution that fits well with how I use my boat.
I would upgrade the prop to the 10 x 12. I enlarged my aperture to fit my new prop in, I'm glad I did. I did some quick calcs for your range to 80% depth of discharge for LiFePO4 cells (these are conservative, but I don't know if your 10" prop will deliver the same efficiency as some of the boats in the 30' range) I'm including some power/speed assumptions, your milage may vary...
3kts @ 600W = 7.8 hours or 23nm
4kts @ 1400W = 3.25 hours or 13nm
5kts @ 3000W = 1.5 hours or 7.5nm
Even though I worried about range under power before I converted my boat, since the conversion, I've never used more than 1/3 of the usable range in normal sailing. I did some deeper discharges right after my conversion while I collected performance data so I know that what my real world range is.
All in all, you sound like you've got your conversion pretty dialed in. I'm looking forward to your reports when the boat is up and running.
Fair winds,
Eric
1964 Cheoy Lee Bermuda 30, 5,5kW Propulsion Marine drive, 8kW LiFePO4 batteries.
Marina del Rey, CA
--- In electricboats@yahoogroups.com, "Mark n Angela" <mstafford@...> wrote:
>
> JB, regarding batteries: generally folks that go with the LiFePO4 battery bank, and a good BatteryManagementSystem, are happy. Lithium cells are sensitive to over- and under-voltages (fire or early death). When kept in their design limits, they seem to last forever. The BMS insures no cell:
> 1. gets too high during the charging process; otherwise one cell could "run away" with most of the charging energy.
> 2. gets too low at discharge; the BMS cuts off the whole bank.
>
> Regarding 48v to 12v converter: the ones I got from ThunderSky actually give 13.6v, the good "maintenance" voltage for lead-acid 12v batteries. This allows a small 12v AGM or FLA battery to cushion the 12v load when lights, radio, depth, bilge want to play at the same time. The 48-12 converter keeps the small cushion battery charged.
>
> Regarding prop: work with Electric Yacht. The motor RPM and shaft gearing should drive those decisions. James Lambden of Propulsion Marine has invested considerable time and money in optimizing prop to motor, and has found extraordinary distance efficiencies by getting it right.
>
> Regarding wind generator: what are your off-dock electrical needs? A wind generator is standard cruising fare, but a huge inconvenience on a 24' sailboat.
>
> Just my opinions,
> Mark Stafford
>
> --- In electricboats@yahoogroups.com, "JBWrites - San Diego Freelance Writer" <jbwrites2@> wrote:
> >
> > Happy Holidays one and all!
> >
> > Have decided on a system for my 1963 Columbia 24 and would love to get the opinion of my fellow eBoat enthusiasts.
> >
> > First, the sailboat is a semi-full keel, which has been soda-blasted clean of 47 years of old paint and epoxy coated (not a single blister by the way!). It has an attached rudder with an apature for the prop. LOA is 24'4", 8' beam, and displaces 5,000 pounds.
> >
> > Powering the 3.5kw system from Electric Yachts of Southern Califormia will be a 48 volt, 120 amp-hour lithium battery bank; the 12 volt system will be powered off the mains via a 48v to 12v converter. In addition to the Regen capabilities (which I assume at 5% as the boat's theoretical maximum hull speed is something like 5.5 knots and too slow to really kick in) I am thinking about an Amp Air wind generator as there really isn't any space for solar panels. Of course, when tied to the grid there will be a 120 to 220 volt charging system in place.
> >
> > As for the prop, I am thinking of having a 3 blade, over-pitched 10:12 fabricated by Deep Blue Yarch Supply – otherwise, I'll be using the original 10:8, 3 blade that was parred with the original 8hp diesel that died with Disco back in the '70s.
> >
> > So, my open question to my fellow eSailors: Have I dotted the "I"s and crossed the "t"s?
> >
>
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