[amsat-bb] Re: Question of the day!
Gordon JC Pearce
gordonjcp at gjcp.net
Wed Jan 11 04:52:10 PST 2012
On 11/01/12 12:12, g.shirville at btinternet.com wrote:
> Hi All,
> It is "said that" NiCad battery cells usually fail to "short circuit"
> and that Lithium Ion ones usually fail by just loosing their ability to
> hold a charge viz they go "open circuit"
> Is this true or....?
> many thanks
It certainly *seems* to be true. We have radios with NiCads that are
still struggling on with reduced capacity but when they go, they go dead
short across the cell. This is because little whiskers of cadmium
eventually grow across the electrolyte.
NiMH doesn't seem to do this, and can otherwise be considered a drop-in
replacement for NiCad.
The Lithium Ion batteries we use seem to hold up pretty well until about
600 cycles, then fall off very rapidly.
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