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Re: ECHO Battery life



On Sunday 27 March 2005 07:29, you wrote:
> Happy easter to all from patrick N2OEQ
> 
> Regarding ECHO; The batteries are rated for a life of 50,000 cycles or 10
> years. 
> 
> How does depth of discharge and subsequent charge levels affect battery
> life? This is a serious question, please , serious informed answers only.
> 
> Thank you, 73, patrick
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Hi Patrick,
   I think that is a optimistic number, the matching of cells surely helps, but 
Ni-Cads  do best when the are charged, completely discharged and then charged 
fully, chronic undercharging or overcharging leads to crystal formation which gives 
you the shorted cells. The worse thing you can have is running a pack down and have 
one cell empty first and then go reverse voltage, the careful matching of the cells
helps prevent that. 
  If you get a really good matched set, where they all discharge and charge equally then you 
end up with a pack like what was on UO-14, no one cell gets under or over charged and the
pack lasts for years and years.
   
  AO-40's batteries died an early death, IMO they were micro-cycled, AO-40 was supposed
to be 3 axis with the panels opened and directed at the sun giving you a steady charge current,
instead because of problems it had to keep spinning with the panels closed, this caused
a pulsating charge effect on the batteries.

Hindsight is always 20-20 but plotting the battery voltage you could see the batteries getting worse
and worse, it probably needed to have charging shut off  let the batteries run down and then recharged
fully to cycle them and possibly regain some capacity.

But one could understand when you have a sat of "iffy" reliability from an accident that you tend
to leave it alone to not make things worse...

   As far as Echo is concerned I have no doubt Mike KE4AZN is very conscientious and is keeping a close eye
on the battery health which is the best possible thing that could happen to ensure a long life for
Echo.

73
Kevin
WA6FWF
#19623
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