I made an Arduino project where I measure temperature and humidity in my small cold frame
greenhouse, write this data along with the time of day to a micro SD card, and also turn on a 12 v fan during certain times of the day. I'm using a Renogy Wanderer solar charge controller (Amazon.com) to charge up a 12 volt sealed lead acid battery. The charge controller also has a load terminal that I've hooked my Arduino to (I read that Arduinos can run on 12 V and up to a max of 20?). I stripped the wires on the end of this type of plug (Amazon.com) and connected it to the load of the charge controller via terminal blocks. When I just have the Arduino and the battery wired up to the charge controller everything works fine. However, as soon as I plug in the solar panel to the charge controller, the Arduino starts acting funny. It seems like the program sporadically resets itself every few seconds (the little reset light will blink a few times the same way it does when you first power up the board and the fan that is supposed to be running will turn off and then on again). If I then disconnect the solar panel from the charge controller, it works fine again, plug it back in and it starts acting weird. It seems like the charge controller does something to the power supply that the Arduino doesn't like when it's trying to simultaneously charge the battery. The battery voltage does increase by a few volts when charging but stays pretty steady although it probably does fluctuate a little, I'm thinking maybe the Arduino is sensitive to this or something. Any ideas on how to fix this issue? Thanks for any help!
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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. I would use a buck converter to drop the 12V to 5V and connect that to the 5V pin on the Arduino, bypassing the, weak, 5V regulator. Then the rated current of the DC DC converter is available on the 5V line.
If too much current is drawn from the on-board regulator it will over heat and shut down, resetting the processor.
What all is connected to the 5V rail on the Arduino. A schematic would help. Hand drawn, photographed and posted is fine. Include all components, their part number and/or values and all power supplies.
Thank you and duly noted
Thanks for the reply, that makes a lot of sense but I will draw one up
I found these work really well dropping the charge controller vOut down to 5V,
May not be the cause of your problem, but something to be aware of if powering through Vin or the power plug.
The Renology does not have reverse current flow protection. Use a diode to stop the battery from discharging through the solar cell, at night. The diode will also protect the solar cell from reverse current damage.
I use these MPTT controllers,
They do not have a power hungry display to power.
How is the coil of the 5V relay powered?
Thanks I forgot to put that in, it's from the 5V off of the Arduino
With 12V into Vin or the power jack that could be a bit much for the on-board 5V regulator. Another reason to use a buck converter 5V output to the 5V pin. Like the one mentioned by @Idahowalker.
Sounds good I'm gonna put one in, thanks!
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