Weather Station Hardware > Remote Weather Monitoring
Power system thoughts?
DanS:
possibility? http://www.millionsolarroofs.com/rogue5ampslachargeregulator6v12v.aspx
SLOweather:
I built 2 of these with the 5 volt regulator for the consoles at Condor Lookout, to run them off the solar system and save the C cells. The consoles just don't draw that much current unless the backlight is on, so the inefficiencies of the linear regulator don't really matter to me. The regulator does get a little warm when the back light is on, so I used the metal cover of the Radio Shack project enclosure as a heat sink.
--- Quote from: DanS on March 16, 2011, 05:08:13 AM ---At the output of the 12 volt solar regulator pop one of these in to regulate down to +6 volts (or a 7805 for +5 volts). Current handling is sufficient. Or you could use a LM317 (adj. version) if you need another voltage (lower than 12v).
(Pic and schematic deleted for space...)
--- End quote ---
johnd:
--- Quote from: SLOweather on March 16, 2011, 10:35:59 AM ---The consoles just don't draw that much current unless the backlight is on, so the inefficiencies of the linear regulator don't really matter to me.
--- End quote ---
Certainly true with the serial/USB loggers, but the IP logger obviously takes more like 100mA so a bit more of an issue unless you have a generously-sized solar PSU.
SLOweather:
--- Quote from: johnd on March 16, 2011, 11:30:58 AM ---
--- Quote from: SLOweather on March 16, 2011, 10:35:59 AM ---The consoles just don't draw that much current unless the backlight is on, so the inefficiencies of the linear regulator don't really matter to me.
--- End quote ---
Certainly true with the serial/USB loggers, but the IP logger obviously takes more like 100mA so a bit more of an issue unless you have a generously-sized solar PSU.
--- End quote ---
Yeah. Instead of the WLIP, I use the serial WeatherLink and my own outboard Serial/Ethernet data hub to send the data from the stations to my server. It draws a little more than a WLIP (165ma at 12 VDC). But, it's a lot more configurable (even remotely from the server) and doesn't heat up the console sensors. The whole solar site (console, interface, and cell modem lives on 7 AH per day at 12VDC at one minute updates.
johnd:
--- Quote from: SLOweather on March 16, 2011, 01:33:40 PM ---The whole solar site (console, interface, and cell modem lives on 7 AH per day at 12VDC at one minute updates.
--- End quote ---
OK, thanks - that's interesting. Couple of questions if I may:
How do you arrive at the 7Ah figure? So the 0.165A draw is from what you're calling the serial/Ethernet hub (is that a device server or something else?) So that's 4Ah. So does the cell modem live on just 3Ah? Thats an average draw of 0.125A or 1.5W @ 12v, which seems quite good. Is the cell modem powered up continuously in the sense of not sleeping between transmits? But presumably the current draw does fluctuate to some extent when an active transmission is under way? So how do you measure the average draw in practice?
And, second, have you ever calculated how many Wh of sunshine you need to generate your 7Ah (Did you say that your total panel power was 150W?) I guess this is only going to be very rough comparison because it will depend on the panel angle. I'm thinking that I should have my panels more vertical than horizontal because you need to maximise the winter power generation (at 52N) - I don't really care about summer power generation because I've got to size the panel array to get through the winter - summer generation is almost irrelevant as long as it exceeds winter. (This sort of argument tends to throw the folk installing panels for power generation because they're keen to maximise summer or year-round generation whereas all I want to do is to get through the winter reliably.) Actually what I would like to know is how to calculate the optimum panel angle to maximise midwinter power generation
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