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Joined: 27 March 2016
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Posted: 19 January 2018 at 1:27pm | IP Logged Quote Phil23

lew247 wrote:
I just bought a 2nd new solar panel
Same thing as the first
only 8 mAh out of this one

Sounds too suspect; I'd be questioning the meter.

Possibly a blown fuse.

Both my Flukes have fuses on the mA & high current ranges.

Either that or the 20A? shunt has blown loose/became dry jointed.

I can get way is excess of 8mA even as the sun is going down here.



Try putting the meter briefly across a AA battery; I get an initial 2A, quickly falling to about 200mA (under a second), but could be the meter auto ranging.

Edited by Phil23 on 19 January 2018 at 1:32pm

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Posted: 19 January 2018 at 8:58pm | IP Logged Quote lew247

The meter works fine
The current coming out of the panel is between 8mAh and 25mAh depending on the amount of clouds
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Posted: 20 January 2018 at 2:56pm | IP Logged Quote redrok

What is the Short Circuit Current in bright sunshine?
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Posted: 20 January 2018 at 5:42pm | IP Logged Quote JohnS

What sort of value would you expect (for what size panel)?

(So as to start on a sane meter setting.)

Also... we don't have ANY bright sunshine this time of year :(
So is it OK to use whatever dim brief sun there is?

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Posted: 22 January 2018 at 5:38am | IP Logged Quote yobortsa

Charging lead acid batteries

#redrok, would you mind giving a working example of charging lead acid's? By 1-2%, do you mean 1-2 amps constant current for a 100 Ah battery? Is that ideally the upper limit? In other words, as sun comes up and goes down, this will be less. And if draw from devices increases, charge may dip.

State of charge

Does anyone have suggestions on measuring state of charge of battery? Simply measuring voltage at a point in time seems very inaccurate - can give charge voltage from panel depending on charge controller, is influenced by current draw at the time and all this takes time to settle if anything changes. Measuring open circuit voltage to get state of charge seems to me to be impossible.

Good thread,

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Posted: 22 January 2018 at 7:13am | IP Logged Quote palcal

I checked my panel I have on my workshop roof when the sun had just set last night.
I guess you could describe the light as the time you would be switching your car headlights on. I got 10ma with the panel across the meter. All I can say is I would not like to live there. Bearing in mind the sun is much lower in the sky in the UK than it is here and a cloud layer I think you are correct Lew.
What is the wind like would a small wind turbine work.

"It is better to be ignorant and ask a stupid question than to be plain Stupid and not ask at all"
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