Welcome to the Cumulus Support forum.

Latest Cumulus MX V3 release 3.28.6 (build 3283) - 21 March 2024

Cumulus MX V4 beta test release 4.0.0 (build 4018) - 28 March 2024

Legacy Cumulus 1 release v1.9.4 (build 1099) - 28 November 2014 (a patch is available for 1.9.4 build 1099 that extends the date range of drop-down menus to 2030)

Download the Software (Cumulus MX / Cumulus 1 and other related items) from the Wiki

Watson 8682 solar charging circuit

Discussion specific to Fine Offset and similar rebadged weather stations
Post Reply
DOC
Posts: 32
Joined: Wed 08 Sep 2010 4:20 pm
Weather Station: Watson W-8681 Solar
Operating System: Windows 10
Location: Guernsey Channel Islands
Contact:

Watson 8682 solar charging circuit

Post by DOC »

Hi All

I am having great difficulty obtaining electrical information on this unit to that end can anyone help me?
I want to find out how much current the transmitter uses and what the max and min current/voltage is generated by the solar panel.

Any source of circuit / electrical data would be useful if anyone can point me in the right direction

Thanks
Doc
AllyCat
Posts: 1124
Joined: Sat 26 Feb 2011 1:58 pm
Weather Station: Fine Offset 1080/1 & 3080
Operating System: Windows XP SP3
Location: SE London

Re: Watson 8682 solar charging circuit

Post by AllyCat »

Hi,

Is it a Solar Charging (only) station or a Solar Data station? AFAIK the model number only tells us it's using 868 MHz.

The "Charging" Pod appears to contain only a small PV panel as shown in the photo on this page of the forum, but there might be a voltage regulator in the "transmitter" (External Temperature, Humidity, Rain and Wind sensor enclosure).

The Solar Data Pod is shown on page 4 of the same thread and includes a Voltage Regulator, I believe 3.3 volts, but then fed via a Schottky diode (presumably to reduce reverse discharge) so only around 3.0 volts reaches the cells. That raises complex issues over the "best" battery technology to use, which I've discussed elsewhere on this forum.

The PV panel is Amorphous Silicon so may have an efficiency around 10%. With an area of 10 cm2 and peak solar radiation (overhead Summer) of 1000 watts/m2, it may deliver around 100 mW, or say 25 mA at 4 volts. In mid winter you may be lucky to average 1 mA over a day in the CI.

Even without solar charging the Transmitter runs for about two years on a pair of Alkaline AAs, perhaps 1000 mA.hrs/year, or an average drain around 100 uA. The actual radio transmitter may take a peak of typically 20 mA, but only for around 100 ms each minute. But there are far too many variables (carrier frequency. data formats, etc.) to be much more specific.

Cheers, Alan.
Post Reply