[amsat-bb] Re: 20-year Li-Ion Packs

[Bob McGwier]

Jon Bloom and the ARRL labs did a great job with the BCR.  While we are 
no longer optimizing the set point for maximum power transfer, the 
batteries do appear to have been a very good choice and the BCR and 
solar panels are working in those which are still talkative.  The South 
Atlantic anomaly appears to be the death bringer.

I personally no longer fear batteries as the likely failure mode over 
the reasonable lifetime of our satellites when designed by someone who 
knows what they are doing.  What these lithiums offer us is much great 
energy density than we can get with NiCad chemistry.  Now it appears the 
first shots have been fired in making them last a long time.  What we 
don't know yet is how structurally sound these new cells with increased 
lifetime will be.  What will temperature cycling and vacuum do to them, etc.

I hope that this progresses and ends any and all speculation about the 
wasted effort (my view alone) on capacitors which do not seem to be 
approaching the energy density of bad batteries.  The density curves 
with caps is looking pretty asymptotic to me.  A big leap is needed to 
make them competitive.

Bob
N4HY



On 2/5/2010 7:04 PM, Mark L. Hammond wrote:
> Hey, AO-16 and IO-26 still have some decent batteries, even after 20 years or so :)
>
> Check their orbit numbers (80k-100k), and that's very close to the number of time they have been charged/discharged!  hehe
>
> Neat on the new technology...but our buddies that built those birds picked some good batteries too!
>
> 73,
>
> Mark N8MH

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