Powering Arduino through Vin from battery pack

Hi everyone

I just starting my adventure with Andruino.
I built a system for watering plants.

SYSTEM

  1. Andruino WIFI rev2
  2. Battery CP1212 12V, 1.2AH and 0.48A of initial current , which I connected directly to GND and Vin pin.
  3. Voltage divider to measure voltage of battery on one of analog pins.
  4. Pump connected to the battery with MOSFED steered from one of digital Andruino outputs

What Happend:
1. I tested system with other battery pack and all work properly.
2. As I connected the system to new battery CP1212, Andruino died.

I am guessing there was too high initial current. I read however that Vin is protected already internal up to 1A. Maybe problem is the current on analog inputs through divider?

I was thinking about the dcdc converter 12v-12v with current limit. But This would have to be bahind pump.
Does it make sense? Do you have some experience with it and some tips

regards
Me

Could You rearrange the drawing regarding the values of the divider values? They are covered by lines.

Be careful when using the power plug or Vin. Powering through Vin or the power jack means that the Arduino and all peripherals that are on the 5V rail are powered by the onboard 5V regulator. The on board 5V regulator is not heat sinked so will supply limited current before it overheats and shuts down. The amount of current depends on the voltage input to Vin or the power jack. The higher the voltage the less current can by supplied before the regulator shuts down. I would use a buck converter to drop the 12V to 5V and connect that to the 5V on the Arduino, bypassing the, weak, 5V regulator. Then the rated current of the DC DC converter is available on the 5V line.

have you connected it backwards? As it stands there is nothing wrong with your diagram, whatever you did is not on it or you are not telling

R3=20kOhm
R5=11kOhm
R4=20kOhm
The idea behind was to measure voltage on R4 and calculate back the battery voltage

Unfortunately not, That would be such an easy solution :wink:
I have actually a bench of sensors and some buttons connected to analog and digital pins. But none of them connected to 12V. I remove them from diagram to keep it clear. I do not think they cause any problems.

Hi groundFungs.
Thanks for tip .But this does not explain why I destroyed the Arduiono, isn't?

I will anyway consider you suggestion to supply the Arduino with 5v using dc-dc converter.
But still, I need to supply pump with 12v and sufficient current and I want to measure current battery level in order to not start pump if level is too low (battery is charged with solar panel). So I would need alternative as well to divider.

Hi guys, what about:
Option1. Should I protect Analog input with a diode and capacitor?
What is actually allowed current on analog inputs? I could not find it.
Option2 some overcurrent protection between pump and divider?

Your schematic should include everything connected

Is your pump a 12v Pump?
What is the statring current of the pump?
Is the Pump in a no load state at start up?

Your are trying to control the pump with a N-Channel Mosfet from a digital pin on the Arduino. Mosfets are voltage controlled and BJT transisitors are current controlled. You would need close to 12v at the gate of the Mosfet (Digital pin from arduino) to fully turn on the mosfet.

Good choice.

Here it is :slight_smile:

thanks!
At least that was done good :*

Here you chalanged me.

Ok so:

  • pump i 12v
  • I do not know initial current but max is 2.2A link
  • what would be a "no load state" of pump :thinking: -> no it does not pump !
  • regarding the MOSFET control , controlig did work with other battery set: pretest with 8x 1.5v

WORKED with :slight_smile: :

DID NOT WORK WITH :frowning: :

Running currents like 2 amp through a breadboard is not good. Those conducting fingers are designed for such currents and will get damaged or destroyed.

P.s.
I just log in asking for help and there is so many people trying to support me!!!!!
I did not expect such an activity!

THANK YOU ALL FOR EVERY FEEDBACK!!!
it motivate for keep trying :slight_smile:

For future reference, the model number of your SLA means nothing. Just the voltage and capacity are all that's required to be useful; ie "12V, 1.2Ah".
Can anyone here comment on the "initial current: less than 0.48A" spec? WTF? It's a battery. Is this thing legit?

Hi Railroader

But Pump can handle up to 2 A and battery deliver MAX 0.48A.
Do I understand it correctly?

And if not what would you recommend? DCDC converter between pump and Arduino? How could I measure then a voltage on battery?

You should have posted this straight away and saved everyone’s time. Fully charged led acid battery can give way more than 12v, so let’s go with what it says on it, 14.9v. what your voltage divider voltage is in this case supplied to 5v pin? That’s right you burned it indeed