I am setting up an Argon to be powered by solar and battery. I have an Adafruit Solar charger (Adafruit Universal USB / DC / Solar Lithium Ion/Polymer charger [bq24074] : ID 4755 : $9.95 : Adafruit Industries, Unique & fun DIY electronics and kits) which will handle accepting the power from the solar panel as well as charging a LiPo battery. The output from the Adafruit board is around 4.4V.
It seems to be acceptable to power the Argon from its VUSB pin as long as not providing power via USB, and I am fine with this. I much prefer to power the Argon from the VUSB pin since I can solder directly to it and do not have to mess with a micro USB connector. I also see that when the Argon receives 5V from the USB connector or VUSB, it drops the 5V down to 3.3V. My assumption has been that feeding it anywhere from 3.3V to 5V would be fine, so the 4.4V from the Adafruit board should be no problem.
I have tested this, and the Argon appears to run fine if I give it 4.4V to the VUSB pin, but the strange thing is that the Charge LED on the Argon will flicker on and off, even though I don’t have a LiPo battery connected to the Argon.
My purpose of posting this is to ask if there is a reason why the Charge LED keeps flickering, and if my assumptions above are incorrect, and it is not okay to power the Argon with 4.4V to VUSB.
For what it’s worth, if I use a boost converter to take the 4.4V to 5V, I do not experience the Charge LED flickering. I just don’t want to implement a converter if I can help it since its one more component to fail.