James,
The quote of $25k was for a converted car, about $11K for batteries and BMS, $7k for AC drive and controller, $3-4K for chargers, instrumentation, DC/DC converter, breakers, contactors, battery supports and boxes, transmission adapter, vacuum pump for brakes, etc. and about $4k for the donor car. Because of the drive systems that are available to DIYers, it takes closer to 30Kwh of batteries to consistantly deliver 100 miles at decent speeds. Obviously, you can save on some of those costs, but then you're stuck driving a science experiment that I don't think is comparable to what Nissan is offering. Most articles list the Leaf around $35-40k before rebates.
Though I don't usually list prices, I've been consistantly quoting the $3600 I paid for my 8kWh batteries with BMS since I received them early this year. For estimates I also use $0.45 to $0.50 per rated Wh to allow for price and shipping fluctuations.
The effective capacity advantage for Lithium decreases as the size of the bank increases. Also, AGM (lead acid) is much closer to Lithium performance than flooded cells, so most of my comparisons have been for the same size pack by rated capacity, not effective capacity. The specifics of each installation have too many variables to simply state that a Lithium pack can be half the rated size.
I'll do two examples based on the assumptions of an 50V pack and an 80A load.
8kWh packs (160Ah):
FLA to 60% DoD = 40.5 minutes - 2,700Wh
AGM to 70% DoD = 66.6 minutes - 4,440Wh (64% better)
Li to 80% DoD = 89.5 minutes - 5,970Wh (120% better)
24kWh packs (480Ah):
FLA to 60% DoD = 159.6 minutes - 10,640Wh
AGM to 70% DoD = 223.2 minutes - 14,880Wh (40% better)
Li to 80% DoD = 277.8 minutes - 18,520Wh (74% better)
Just for fun, 48kWh packs (960Ah)
FLA to 60% DoD = 382.2 minutes - 25,480Wh
AGM to 70% DoD = 478.8 minutes - 31,920Wh (25% better)
Li to 80% DoD = 567 minutes - 37,800Wh (48% better)
The only difference is the size of the battery banks. On the 24kWh packs, the Lithium batteries only deliver 25% more energy (Wh) than the lead acid AGM batteries at the stated load. At lower loads the differences are smaller.
Fair winds,
Eric
Marina del Rey, CA
--- In electricboats@yahoogroups.com, James Sizemore <james@...> wrote:
>
> The Leaf has a 24kwh pack, using current prices for LiFePo that would cost around $9000.00 bucks. In a boat at 48 volts that would give you a whopping 500AH pack, which would be equivalent to a 1000AH pack in lead for useful energy out.
>
> And LiFePo have a fair amount of DIY balancers on the market. Such as : http://www.schulze-elektronik-gmbh.de/LiPoProB-e.htm
>
> Eric is there a reason you always double or more the cost of LiFePo batteries packs? LiFePo have not cost $25K for 24kwh pack in well over a year or more. You seem to quote the same inflated number over and over. Not looking for a fight just curiosity is getting the better of me.
>
>
> On Jul 26, 2010, at 1:25 PM, Eric wrote:
>
> > These are the Lithium batteries that have been available to DIYers for the past few years at reasonable costs. I have a set of Thundersky Lithium Iron batteries for the conversion of my 30' ketch.
> >
> > The DIY EV guys have been able to build 100 mile per charge car conversions that cost about $25k for a while.
> >
> > Fair winds,
> > Eric
> > Marina del Rey, CA
> >
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