Turn Project Off Until Battery is Fully Charged

Hello Arduino Forum, I have been working on a solar powered project for an art installation. The project consists of solar panels, this battery charger, a lipo battery, 5 volt stepup, and arduino+peripherals. The problem that I am having is that the battery will not charge while the arduino is on and running; power is consumed faster than it is generated. However, when the arduino is unplugged from the charging circuit, the battery charges adequately. I would like to add something to either my circuit or code that will disable the arduino (turn off) until the battery is fully charged, and then turn the arduino back on. Does anyone have any ideas on how to do this? Any help would be greatly appreciated. Thanks, icecats

  1. get a bigger solar array so there is ample current to both charge the battery and operate the Arduino.
  2. run the Arduino in a low power mode
  3. if the 'Done' status on the charging board is false run the Arduino in power saving mode
  4. if the 'Done' status is false, have a disconnect circuit remove power from the Arduino.

Thanks for the reply. Will you please expand on this option:

  1. if the 'Done' status is false, have a disconnect circuit remove power from the Arduino.

Could you point me to/describe how a disconnect circuit could be constructed. That sounds like exactly what I had in mind. Thanks, icecats

The "C" and "D" pads on the charger board are "Charging" and "Done" according to the schematic - those are the ones you want to look at.

I will assume the status 'Done' is 0-5volts and 5volts means the charging is done/finished.

Feed the 'Done' status to a transistor driver controlling a low current 5 volt relay. The relay would control the power to the Arduino.

Alternatively you could use a logic level MOS FET to connect the power to the Arduino.

How is the Arduino powered from the battery now?


The Arduino is powered from the Adafruit charging circuit previously linked, through a 5v stepup, and to the Arduino.

I can see a potential problem with this method; correct me if I am wrong. Once the battery is charged, the DONE line will be high and the disconnect circuit will deactivate, turning on the arduino. The arduino will operate and cause the battery to become no longer done, but charging. This will pull the DONE line low and turn off the arduino. It seems like this will be an ever cycling loop in which the arduino doesn't have a chance to perform for very long. Thoughts? Thanks, icecats

Do you have a link to the theory of operation for the board? .

Would this work? https://learn.adafruit.com/usb-dc-and-solar-lipoly-charger?view=all


"The orange CHRG LED indicates current charging status. When this LED is lit, the charger is working to charge up a battery! It also acts as a low battery indicator (fixed at 3.1V) when no power is connected. So, if you don't have USB/Solar wired up, when the battery voltage drops below 3.1V, the orange LED will come on. The green DONE LED is pretty easy to understand as well - when it's lit the battery is charged up! Very handy for when you want to know that everything is done."

When the 'Done' status comes on at full charge a flip flop could be set. Then USB/Solar would be disconnected and the Arduino would be connected. As the battery discharges to the point of 3.1v you could reset the the flip flop. When set the Arduino would be connected, when the flip flop was reset the Arduino would be disconnected.

Edit: the bold area added.


Awesome- I will give it a try. Thanks for all of the help. icecats