[time-nuts] Phase noise measurement (was - no subject)

[Poul-Henning Kamp]

In message <4C703124.20404 at xtra.co.nz>, Bruce Griffiths writes:
>Poul-Henning Kamp wrote:

>NIST found that NiCd cells are very quiet at least for low load currents:
>
>http://tf.nist.gov/general/pdf/1133.pdf

Too bad they didn't include lead-acid in that test...

>Perhaps its the gelled electrolyte that is the source of the noise 
>problem with VLRA batteries??

The batteries I used were pre-owned AGM, and apart from possibly
the frequency spectrum, I wouldn't expect AGM/Gel to make any
significant difference.

The very few hints I have been able to find, talk about bubbles
and mechanical shifts in the particulate matter in the electrodes
but they were all trying to divine battery health from these
entrails, rather than measuring the absolute magnitude of the problem.

Poul-Henning


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