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"Robin" wrote in message
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(I can't measure the current through the clock without
'breaking-open' the circuit (ammeter must be ins series), which I
don't want to do.)

I'm probably missing the point but I'd thought that you would have access
to the terminals to which the battery was connected and so could connect
across them a resistor of (say) 470k [1] and then measure the voltage and
current when the cells are in sunlight.


[1] total guesstimate based on a Lion cell requiring a charging voltage of
~3.6V and anything less than a few microamps not being worth the candle

--
Robin
PM may be sent to rbw0{at}hotmail{dot}com

Thanks Robin, but I don't have any 470k (or other) resistors to hand. Just
a multimeter
that I use for checking electrical things.

In any case, surely measuring the current though a resistor between the
terminals
would only tell me if the charging circuit was working (solar cell
delivering current to the battery).
It wouldn't tell me if current was being delivered to the clock
- to do that the meter would somehow have to be in series with the clock..

Steve