Re: [amsat-bb] ECHO Battery life

[McGrane <tmcgrane@xxxxxxxxxxxxxxxxx>]

Hi bob- thanks for info, I know you have made a satellite so I value the
information. Thank you very much, 73, pat n2oeq


On Tue, 29 Mar 2005, Robert Bruninga wrote:

> >>> McGrane <tmcgrane@suffolk.lib.ny.us> 3/27/05 10:29:39 AM >>>
> >The ECHO batteries are rated for ...50,000 cycles or 10years. 
> >How does depth of discharge [DOD]... affect battery life? 
> >This is a serious question, please ,  informed answers only.
> 
> >From Space Mission Analysis and Design: For NiCd's
> For 80% DOD you might get 300 cycles
> For 60% DOD you might get 1000 cycles
> For 40% DOD you might get 5000 cycles
> For 20% DOD you might get 25000 cycles
> 
> Most space applications design for 20% or less DOD.
> 
> So it really pays to not deep discharge your batteries. !
> I know this flies in the face of "consumer wisdom" that 
> says to deep discharge every time, but that is only the 
> recommendation of the Battery MFRS that want you to 
> buy a new battery pack every year!
> 
> How can they get by with saying such a thing?  Simple:
> They base their claim on your need for MAXIMUM 
> performance on every use.  In that case, you are
> trading off maximum LIFE for maximum PERFORMANCE
> and they are right.  Because the deep discharge and
> full soak recharge balances the cells so that on the
> next use, they may last a few minutes longer... But at
> DRASTICALLY reducing the overall life of the cell (and 
> maximizing their ability to sell you more batteries)..
> 
> Buyer beware... and be informed....
> 
> In space, you cannot buy another pack...
> de WB4APR, Bob
----
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