T-Pain Is On A Boat: Re: [Electric Boats] RESULTS ..... VERY GOOD

Friday, June 24, 2011

Re: [Electric Boats] RESULTS ..... VERY GOOD

On Fri, Jun 24, 2011 at 04:41:44PM +1000, chris Baker wrote:
> Hi Ben,
>
> I'm a fan of Thundersky batteries, having had them on my trimaran for a couple of years now, and I'm putting another set into a solar boat right now.
>
> A suitable set of Thundersky (or CALB) cells could be based around the 400ah cell. They 3.2 volts each and you'd need say 24 of them for your target 72 volts. So a much smaller battery farm than the trojans.

That's a pretty amazing cell; surprising power density, especially for
that low weight. The biggest problem is the cost: $430 apiece here, so
over $10k just in batteries alone is prohibitive. But it sure would be
nice. :)

I just ran across the L-16 type Crown CR-395 battery; 395AH @ 6V, so 12
of these would give me what I need. Just over $250 apiece, which works
out to just over $3k total; 121 lbs. and a 12.2"x7.2" footprint, so
under 1500 lbs. and two rows (roughly) 1' wide and 4' long. That should
fit in my engine compartment - although it will shift the weight
distribution quite a bit: currently, I have 2 x 50 gallon diesel tanks
in the main salon, with their centers about 5' forward of the engine
compartment; between the fuel and the tanks themselves, that's about
1000 lbs. The diesel itself sits right where the batteries are going to
go. If I remove the tanks and the engine and install the batteries and
the motor, the weight swap will be fairly close to even - but as I've
mentioned, the distribution is definitely going to shift quite a bit.
I should probably consult a marine architect, but I have a sneaking
suspicion that it's not a viable setup. I might have to see what the 60V
power curves look like, or look at AGM and the like.

Thanks, Chris - that was really helpful!

--
Ben Okopnik
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
If you want to build a ship, don't drum up people together to collect
wood and don't assign them tasks and work, but rather teach them to long
for the endless immensity of the sea.
-- Antoine de Saint Exupery