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Topic: Solar Power (Read 1 time) previous topic - next topic

nat45928

Nov 20, 2012, 06:46 am Last Edit: Nov 20, 2012, 07:04 am by nat45928 Reason: 1
Hi,

I was wondering if someone could point me towards a good starting point for a solar/battery power solution for an Arduino? I found this: http://www.instructables.com/id/Self-Sufficient-Arduino-Board/?ALLSTEPS but i'm not sure if this would prevent over-charging or dis-charging the batteries. I'm a new Computer Engineering/Electrical Eng student so the goal here is to learn how/why/what I should do. So any help by some more experienced guys would be awesome!  :)

I also found this online and seems to be like a good little function:

Code: [Select]
float read_battery(void) { // Honk, 14 - 11 - 10 (function was totally missing in NG trunk)
  /*Circuit:
   
    Vin--D1--R1--|--R2--GND
                 |
                 |
                Vout
  */
  //If lipo is 12.6V and diode drop is 0.6V (res 12.0V), the voltage from divider network will be = 2.977V
  //calculation: AREF/1024.0 is Vout of divider network
  //Vin = lipo voltage minus the diode drop
  //Vout = (Vin*R2) * (R1+R2)
  //Vin = (Vout * (R1+R2))/R2
  //Vin = ((((AREF/1024.0)*adDECIMAL) * (R1+R2)) / R2) + Diode drop //(aref/1024)*adDecimal is Vout
  #define R1 10050 //the smd 10k from battery
  #define R2 3260 //the div resistor user put in (3k3 makes for about 13.5V before hitting AREF 3.3V)
  #define AREF 3.3F //we have used analogReference(EXTERNAL)
  #define DIODE_FWD_VOLTAGE_DROP 0.6F //measure with DMM across D1 (input diode in series with Vin)

  float batteryVoltage = (((analogRead(VDIV1)*(AREF/1024.0)) * (R1+R2)) / R2) + DIODE_FWD_VOLTAGE_DROP;
  return(batteryVoltage); 
}


Thanks,
Nat

xvjeko

First of all, it depends on how much current would you draw...
If you plan to build projects with large motors, you won't be able to charge the batteries at all.
I recommend you find all electronics on ebay, and you will need batteries and solar panels + some kind of "charger" (voltage regulator).
For batteries i would personally go for some kind of Li- batteries, but my favorites would be LiFePO4.
For solar panels i would pick whatever size you need (depends on space available, power needed, etc.).
First you need to calculate the whole thing, to see how big system would you need...

If you can't make such calculations, feel free to post detailed specifications about your system.  :smiley-mr-green:

Docedison

@ xvjeko,  ???   
Quote
If you plan to build projects with large motors, you won't be able to charge the batteries at all.
Why Not? Certainly with the right sized panels and batteries, I should think the OP could run any sized motor.

Bob
--> WA7EMS <--
"The solution of every problem is another problem." -Johann Wolfgang von Goethe
I do answer technical questions PM'd to me with whatever is in my clipboard

dhenry

Quote
I also found this online and seems to be like a good little function:


That function reads off the battery's voltage. It doesn't power the arduino.

Docedison

@ *dhenry* Don't you think a battery monitor is a "beginning" to a battery charger?. I think that even with your "Lofty" Native Intelligence You really know that code can't power an Arduino... ---   I Know, You're Just Testing all the rest of us..

Bob
--> WA7EMS <--
"The solution of every problem is another problem." -Johann Wolfgang von Goethe
I do answer technical questions PM'd to me with whatever is in my clipboard

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