Design solar panel with bateries for fan in radiation shield

[weather1967]

Hi all
I make a electronic design (and i thing to build it )for to work a pc fan in a radiation shield
The day it will turn foul turn with 12 volt dc ,at the night at half turn with 6 volt dc
For low drop the volt from 12 volt to 6 volt i use one resistor 80 ohm at 1 watt from the type :
12-6/0.075 =80 και 6*0.075 = 0,45w
Sollar panell --> charge controller-->battery-->80 ohm resistor to relay for 6 volt dc at fan the night.
Solal panel--> 12 volt at fan the day ,
Solar panel -->i use 162 ohm resistor for drive to relay to cut the contacts to relay at 10 volt dc and down because before without resistor the relay closed the contacts at 7 volt dc (i make experiments with a power suply 0-30 volt).
Fan--> to relay

When it is day with sun solar panel give 12 -16 volt and the relay closed to batery circuit and solar panel it give power to fan ,the night the when drop the power from solar panel ,open to circuit to relay and give power to fan from the battery .

Tha material it is

A sollar panel 12-16 volt 10 watts

http://elektronik.gr/eshop/index.php?main_page=product_info&cPath=467_468&products_id=18249

A charge controler 12 volt 5 amber

http://www.maplin.co.uk/Module.aspx?ModuleNo=37774

one batery lead acid 12 volt 7,2 Ah,or 17, Ah for better results.

http://www.batteries.gr/product.asp?catid=2668

a pc fan for radiation shield 12 volt 8 x 8 cm

http://elektronik.gr/eshop/index.php?main_page=product_info&cPath=87_627_628&products_id=13784&zenid=34c58359c1d375a7f42f4cf3d69766d9


one relay 12 volt.

http://elektronik.gr/eshop/index.php?main_page=product_info&cPath=232_1906_245_1868&products_id=16973


a water proof case for to put inside batery,charge controler,pcb with relay and 2 resistors

http://www.emimikos.gr/shop/product.php?productid=17464&cat=505&page=1


Here it is the electronic design

[icke]

Hallo Dimitris

For a "self made" Weather station?
On my VP2, I have the daylight fan running with the solar panel, at night its stops. No back up Batteries or Accus.  And I forget to connect the plug some times back; there were no crucially changes in the temperature readings... neither at day or night, compared to the days before and after I reconnect the fan. And the day/night temperatures are anyway the same as the other, none aspirated, temp.-sensors readings.
Therefore, next time I will spend the money on some other extras, no... no not for beer, but not for a fan again. But... there maybe are Weather stations where a fan makes the difference.

Greetings from Namibia to Greece

Thomas

[weather1967]

Hello Thomas
I understand you buy extra the davis fan day time only

http://www.ukweathershop.co.uk/acatalog/davis_7747.html

The complete Davis 6153 model and higher,they have and batteries back up and the fan turn at half turn the night.

It is necessary for the cold nights with temperature inversion the cold air make reflaction from the ground to up ,if we do not have fan the sensor it can to show very lower temperature early the morning ,where it is wrong ,if the fan turn to half turn ,put up the cold air from the radiation shield and the temperature it is more normal.

Many Greetings to Namibia from Greece

[icke]

Ja, Dimitris,

I know that, but it isn't hundred percent right. For that phenomenon the air must be absolutely stand still. No wind, thermic at all. And that is in 99% of all nights/mornings not the case. I had the WS444PC running next to the VP2 for some time; there was no difference in temperatures. And the KS555 has not a fan at all. Even now, our Weather Wizard 3 in the back shows a slightly lower temperature as the ISS from the VP2.
One or two degree centigrade difference in temperature between the back and the front of a house where the sensors are, that is almost nothing. For me is that more as good enough. But for an Tec-freak... you can blow air through the sensor housing... the difference is 0.01.

Keep well

[weather1967]

Ηi again i up load a video about test the electronic circuit , with two power supply 12 volts,and all work fine .I measurement the current mA with two multimeters.

http://www.youtube.com/watch?v=OFz19Rnfazs

And all the concept it is here

http://users.otenet.gr/~meteo/project_solar-panel-electronics.html