Cheers Jim,
Do you have a good write up explaining the structural differences with the Li cell types? (you mentioned prismatic vs ??? )
How are Corvus able to make batteries with these claims of massive load and unload capability.. plus full discharge.. and no damage to the cells??
Is it even possible that anyone is aware of?
Thx
Bill
--- In electricboats@yahoogroups.com, James Sizemore <james@...> wrote:
>
> I have priced Corvus packs and they are four times the cost of your typical chinese prismatic cells. they are in the same price range a Mastervolts lithium cells. Basically they are unaffordable.
>
> Best to buy the cells and BMS yourself, and build your pack. If you want to stay anywhere near your 100K target. With current pricing you can buy a 800 AH LiFePo4 pack for around $18,000 with BMS. I recommend the cells below. I have no recommendation on BMS (still undecided myself.)
>
> http://www.evsource.com/tls_lithium_calb.phphttp://lithiumstorage.com/index.php?main_page=product_info&cPath=&products_id=40&zenid=i92g73ucddgr7o1l1a4gb1u561
>
> On Aug 22, 2011, at 11:16 PM, Galstaf wrote:
>
> > Batteries:
> > Goals –
> >
> > Use a Li based system for energy density, lower mass, and ease of use. Really interested in something that is as easy to manage as possible. As Eric estimated I would need 110,000 Whr approximately to go for 24 hours at 5 knots without any replenishment at an estimated cost of $46K, I have revised that to half that figure for weight and expense reasons.
> >
> > 12 hours of drive time should be sufficient 90%+ of the time. If I need the extra umph at that point, it is time to kick on the genset.
> > So that would put me at 55000Wh of capacity at an estimated cost of $23K, right?
> >
> > I have been interested in the Dow Kokem marine duty batteries for a while now just because they claim they are pretty much indestructible regardless of DoD and charging rates. They also say each battery has it's own web server engine to provide centralized health stats on each battery.
> >
> > http://www.corvus-energy.com/marine.html
> >
> > Questions:
> > * Are these claims pie in the sky?
> > * Does anyone know of anyone that has used these batteries and BMS in production?
> > * Does anyone know approximately what these Dow batteries cost per Wh?
> > * Does anyone know anyone else that can boast of these properties at a lower cost?
> > * What are your recommendations on where to shop for Li batteries?
> >
> > The manufacturer claims that you cannot hurt these batteries by fast charging them. They also claim no damage even with a full 100% discharge. Would it make sense then to buy an oversized genset and charging system so that a replenishing charge could be dumped into the batteries in short order and the genset (with it's incessant vibration noise) could then be shut down?
> > The oversized Genset could also help push the motors along in case of emergency when speed IS key to avoiding a storm or getting to safe harbor. Comments?
> >
> > Any other comments about the BATTERY portion of this project, please feel free to be as verbose as possible. Links to manufacturers, and any and all pricing and performance data is sincerely appreciated.
> > My best,
> > Bill
> >
> >
>
Monday, August 22, 2011
Re: [Electric Boats] Re: 60 foot Solar Cruiser - Project Breakdown Part 1: Batteries
They make there claims based on the robustness of there BMS, not that they don't have plenty of markup worked in to pay any warranty claims! For large traction batteries you will want prismatic vs cylinder type batteries. The number of connections need for cylinder style batteries would be atrocious. LiFePo4 is the most forgiving chemistry of thermal runaways, and is generally the cheapest of the lithium chemistries. At the expense of some energy density. But a debate of the best chemistry is mostly moot, in that almost all the BMS and monitoring products only support LiFePo4, because it is the most popular chemistry with the car conversion crowed.
On Aug 22, 2011, at 11:46 PM, Galstaf wrote:
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