Required Sunlight

At what Brightness/Solar Radiation does the Tempest receive enough energy to function and then start adding charge to the battery? I live in a cloudy area in the winter and am interested when that line is crossed on a cloudy day or early morning.

not an easy question as the birghtness sensor is looking in a horizontal plane and the solar panels are mounted vertically. But it is save to say that they need direct sunlight to function.

To add to what @sunny said, it seems to typically need to be a little under 200W/m^2 for good charging to occur.

It appears with my current Tempest the highest solar radiation has been 160 and it was charging well so it must be some point below that.

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To add another data point: charging from empty for a full day of sunshine (7 hours) in January at latitude 52°N gives me around 5 days of sun-free operation before the Tempest shuts down again. Peak solar radiation detected was around 170 W/m2.

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the slope should change when it drops below 2.42 and again when it drops below 2.39 and again at 2.35V. Yours only appear the change when it reaches 2.35V.
It would be way better if they allowed us to choose to reduce the sampling to a max of once every 15 or 30 seconds in winter. No idea why that hasn’t been implemented by now.

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I agree that it’s odd that the power saving measures only seem to have an effect after reaching mode 3. Would indeed be very nice to have some control over sampling intervals.

did the wind sampling rate reduce at all? perhaps keep an eye on it when it happens again.

Actual power save modes are like this (mentioned on this page)

Power Save Modes

Here are details on how the Tempest may conserve power in order to operate for as long as possible. Most Tempests never go below Mode 0 and more than 90% will never go below Mode 1.

Mode 0: Voltage ≥ 2.455

  • All sensors enabled and operating at full performance

  • Wind sampling interval every 3 seconds

Mode 1: Voltage ≤ 2.415 from Mode 0 or ≥ 2.41 from Mode 2

  • Wind sampling interval set to 6 seconds

Mode 2: Voltage ≤ 2.39 from Mode 1 or ≥ 2.375 from Mode 3

  • Wind sampling interval set to one minute

Mode 3: Voltage ≤ 2.355

  • Wind sampling interval set to 5 minutes
  • All other sensors’ sampling interval set to 5 minutes
  • Haptic Rain sensor disabled from active listening
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actually that is exactly what I mentioned, but clearly it doesn’t seem to influence his discharge curve, until the unit hits mode 3

It seems my Tempest turns off wind sampling completely when it hits Mode 3, at least on the UDP stream: "obs":[[1643532104,null,null,null,null,300,1000.84,6.14,62.00,1963,0.06,16,0.000000,0,0,0,2.353,1]]

It reports wind sampling rate as 300 seconds, but only ‘null’ is delivered for the wind values.

Edit: it seems only the “rapid_wind” event is delivered in power saving mode, so wind sampling is still active.