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re: $windpower-energy storage$
3 may 2000
tim o'flaherty wrote:
>>trojan rates batteries in "lifetime energy units," ie the total amount
>>of energy that a battery can store over its lifetime. for instance, they
>>say a t-105 battery can store a total of 438 kwh over its lifetime, ie
>>that's the depth of discharge times the number of cycles in its lifetime,
>>so a $65 t-105 stores energy at a cost of $65/438kwh = 14.8 cents/kwh
>>over its lifetime...
at a 0% interest rate, ignoring inverter cost and inefficiency, battery
inefficiency, and battery maintenance and transportation and conditioned
storage space and recycling cost...
>i took a look at trojan's website, i see the t - 105 at 6v and 25 amps for
>about 7.5 hrs or 75 amps for just under 2 hrs for a range of 144ah to 186ah.
that sounds more like a capacity vs current calc (does it fit their formula
i = 4436.6t^-0.8596 for a t-105 with i in amps and t in minutes?) than
a lifetime energy storage calculation.
>at this site they didn't mention it's lifetime kwh. do you know the
>discharge rate and no. of cycles they assume?
leu's are mentioned somewhere on that site, described as a new technique
and specified for each of their batteries. trojan calculates the area under
the dod vs discharge life cycle curve (which i didn't see there), which
seems conservative vs picking the optimal dod. the t-105 dod vs #cyc curve
they sent me shows about 750 cycles at 100% dod (leu = 473 kwh), 1000 at 70%
(441), 1500 at 42% (397), 3000 at 20% (378), and 5500 at 10% (347), so
fewer batteries with larger dods seem to optimize the leu and cost per kwh,
even with a 0% interest rate and no shelf-aging of batteries, and so on.
nick
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