Also if you use regeneration, such as solar or wind, they will have to be larger on with the Trojans as well. Not as big an issue if you can use shore power.
--- In electricboats@yahoogroups.com, "Eric" <ewdysar@...> wrote:
>
> Jim,
>
> I'm not sure what number that you're looking for, but here's a bunch of data comparing my battery bank to a set of T-105s.
>
> 8kWh bank of LiFePO4 batteries, cost $3600 including BMS, tax and shipping, weight 200 lbs. Manufacturers lifespan is > 2000 cycles at 80% DoD.
>
> Assuming 1 deep discharge per week for 10 years:
> 6400Wh x 500 cycles = 3,200,000Wh delivered
> 3200kWh / 200 lbs = 16kWh/lb
> $3600 / 200 lbs = $18/lb
> $18 / 16kWh = $1.125/1000Wh delivered
>
> From what I know about Trojan T-105s
> 11.25kWh bank of 8 T-105 batteries, cost $1200 including tax and shipping, weight 500 lbs. Manufacturers lifespan is less than 500 cycles at 60% DoD.
>
> Assuming 1 deep discharge per week for 5 years:
> 6750Wh x 250 cycles = 1,687,500Wh delivered
> 1687.5kWh / 500 lbs = 3.4kWh/lb
> $1200 / 500 lbs = $2.4/lb
> $2.4 / 3.4kWh = $0.70/1000Wh delivered
>
> But these numbers aren't the whole story. Because of the different battery chemistry and Peukrert's Effect, T-105s deliver much less energy under load than the Li batteries do. Assuming a 2kW load, the T-105s should deliver 4920Wh in a 60% DoD cycle, the Li batteries will deliver 6100Hh in an 80% DoD cycle. Here's the same calcs again:
>
> Assuming 1 deep discharge per week for 10 years:
> 6100Wh x 500 cycles = 3,050,000Wh delivered
> 3050kWh / 200 lbs = 15.25kWh/lb
> $3600 / 200 lbs = $18/lb
> $18 / 15.25kWh = $1.18/1000Wh delivered
>
> Assuming 1 deep discharge per week for 5 years:
> 4920Wh x 250 cycles = 1,230,000Wh delivered
> 1230kWh / 500 lbs = 2.46kWh/lb
> $1200 / 500 lbs = $2.4/lb
> $2.4 / 2.46kWh = $0.98/1000Wh delivered
>
> So for this usage pattern, the lithium batteries cost 20% more per delivered watt hour but are only 40% the size and weight of the T-105s.
>
> I don't know how relevant these numbers are, since they are based on a broad set of assumptions, but those assumtions are stated here. Change the assumptions and the results will change. From my perspective, this is a fair comparison.
>
> Fair winds,
> Eric
> Marina del Rey, CA
>
> --- In electricboats@yahoogroups.com, "luv2bsailin" <luv2bsailin@> wrote:
> >
> > Right on Steve, but I suggest running them down more to increase range without increasing weight. If you only go to 50%, then half that lead is just ballast. Even if they only last 5 years, that's about $200 per year at today's prices. I'm sure most power boaters spend more than that on maintenance.
> > It would be interesting to compare cost per pound per cycled watt-hour or some such bench-mark for various usage patterns. I know there are a couple spreadsheet gurus on this site...
> > Cheers,
> > Jim McMillan
> >
>
No comments:
Post a Comment