battery cycle life [RE-wrenches]

[Ray Walters]

<x-flowed>
 

Your free subscription is supported by today's sponsor:
-------------------------------------------------------------------
Buy Stocks and Index Funds for just $4 No Account or 
Investment Minimums and No Inactivity Fees Automatically 
invest weekly or monthly and build your future.
http://click.topica.com/caacVmlbz8Qcsbz9JC9a/Sharebuilder
-------------------------------------------------------------------


>Hi;


Did you take into account the variation of AH capacity relative to 
discharge rate (Puekert's Exponent?) That changes the calculations too. I 
did a spread sheet for a customer to compare different battery types for 
total cost per KWH over their lifespan. I included  maintenance & 
replacement costs. The L16s were the worst. The golf cart batteries were 
the best deal not considering maintenance, and the big cells (Rolls series 
5000) were the best deal in the long run including maintenance costs, but 
that was with a healthy discount . At retail prices, the golf cart 
batteries are the best (If the customer maintains them)
 From the chart below, The L16 has 600 cycles at 100% DOD, the T105 has 750 
cycles at 100%DOD. I quit selling L16s all together about a year ago.

Cheers to a better New Year,

Ray




>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

==========================================================
Extra! Extra! Read all about it! Get the latest weather,
sports, and lifestyle news you can't afford to miss, all
at a price you can afford to pay!  Click now!
http://click.topica.com/caaa9eYbz8Qcsbz9JC9f/TopOffers
==========================================================
- - - -
To send a message: RE-wrenches at topica.com

Archive of previous messages: http://lists.topica.com/lists/RE-wrenches/read

List rules & etiquette: www.mrsharkey.com/wrenches/etiquette.php

Check out participant bios: www.mrsharkey.com/wrenches/

Hosted by Home Power magazine

Moderator: michael.welch at homepower.com
--^----------------------------------------------------------------
This email was sent to: michael.welch at homepower.com

EASY UNSUBSCRIBE click here: http://topica.com/u/?bz8Qcs.bz9JC9.bWljaGFl
Or send an email to: RE-wrenches-unsubscribe at topica.com

For Topica's complete suite of email marketing solutions visit:
http://www.topica.com/?p=TEXFOOTER
--^----------------------------------------------------------------



</x-flowed>