[amsat-bb] Ni-Cd's on Satellites and MASS advantage!

[Jerry Buxton]

Amen.

Jerry Buxton, NØJY

On 3/14/2020 11:53, Robert Bruninga via AMSAT-BB wrote:
> We have used NiCds on all of my 4 satellites with no battery problems.
>
> They are robust, and survive all student mistakes and require no Battery
> management system when paired with a matching solar panel design.  IE, as
> th batteries approach full charge is the same point where the solar panel
> voltage maxes.  Also NiCd's can be safely overcharged at 10% indefinitely
> with no concern. (you only get an hour in the sun and then 35 minutes
> eclipse)...
>
> Yes, they are twice as heavy as Lithium, but the advantages FAR outweigh
> the criticality of Lithium concerns and complexity of the BMS and total
> failure on overcharge or undercharge.
>
> And MASS is an advantage!   PSAT and BRICSAT-1 are identical 1.5U cubesats
> launched at the same time in May 2015.  But PSAT with big C cell NiCd's was
> made heavier with lead ballast to 2.3kg.  BRICSAT (1.7 kg) with lightweight
> Lithiums has already decayed in November.  PSAT is predicted to last 2 more
> years!  Same thing for identical RAFT and MARSCOM cubesats back in 2006.
> RAFT was ballasted up and lasted TWICE as long as MARSCOM.
>
> For comm satellites, there is no reason to come in under mass.  Always
> ballast up  to the maximum the launcher will allow!
>
> Bob, WB4APR
>
>