battery cycle life [RE-wrenches]

[William Korthof]

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Very interesting cycle life curve. If you convert the data to equivalent
full-cycle values, ie, 10% x 4398 = AH of 439.8 full cycles. And from
that, it's easy to see the most economical DOD design:

E-Cycles        DOD
440             10%
464             20%
484             30%
506             40%
518             50%
530             60%
542             70%
558             80%
570             90%
600             100%

Based on this data, the economically optimized configuration would
be designed around the deepest possible DOD. If the data is correct,
there is clear *penalty* for shallow battery cycling, and a *benefit*
to deep cycles. When you also consider the time-value of money,
a smaller pack lets you keep the incremental cost for a larger pack
in you pocket (or bank, collecting interest) until later when needed.
The important negative factors are that 1) designing around deep DOD
leaves less margin for discharge variation/capacity decline, 2) more
frequent battery pack replacements do come with a cost.

In any case, this does sort of corroborate peoples not-so-great
results with L16 packs for solar applications (vis a vis cheaper
golf cart batteries or "real" solar batteries).

/wk

For example, at 50% DOD you get 518

At 07:09 AM 12/29/2004, Todd Cory, Mt. Shasta Energy Services wrote:

>Replying to my own message again... I checked out the spreadsheet... here 
>it is
>in plain text:
>
>L16
>exp. cycles   % DOD
>4398                 10
>2322                 20
>1614                 30
>1266                 40
>1036                 50
>884                   60
>774                   70
>698                   80
>633                   90
>600                   100

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