@apt The PMIC has a function that allows you to set the minimum input voltage which will keep the voltage of the solar panel from dropping out when it’s current starts to drop out and it works really well.
The PMIC function looks like below:
power.begin();
power.setInputVoltageLimit(4840); //Set the lowest input voltage to 4.84 volts. This keeps my 5v solar panel from operating below 4.84 volts (defauly 4360)
@dcliff9 - Another alternative, to best use the power envelope of a solar panel, is a buck/boost regulator between the current sourcing panel and the voltage dependent load, eg. a Pololu 5V Step-Up/Step-Down Voltage Regulator S10V4F5 (https://www.pololu.com/product/2121), or similar. Lots out there.
Cheap as chips, and you’ll get the best out of your panels.
I’m using another Pololu device in my 5V prototype (running from 12v lead-acid batt plus solar panel/charger), and it runs cold and efficient.
@RWB - Cheers. I’ve not played much with setting up the PMIC (having a fat battery as the main power source, I’ve not been too worried about it), but thanks, I’ll keep this in mind for future ref.
Thanks apt!
Forgive my ignorance but I was under the impression that the PMIC would regulate voltage input between 3.9 to 12V already. Adding this regulator would allow me to grab more from the bottom end but overall would reduce efficiency by around 20-30% when my panel is putting out over 3.9v, would it not?
Or am I understanding everything correctly.
Your right, there is no need to add any external voltage regulators for solar charging the Electron since the built-in PMIC does a great job at this already if your using the 6v solar panels and set the input voltage limit to keep the voltage of the panel from dropping too far below it's Vmp (Maximum Power Point).
This is a good way to keep the solar panel operating in a voltage range that supplies the most current under all weather conditions.
For most applications this is all your going to need as far as keeping the Electron charged up enough keep going every day. If you have other higher power loads your needing to power that is when you would need to maybe look into an external MPPT solar charge controller to charge a larger battery that would run the Electron and other higher power equipment that the Electron may be controlling.
As noted above, I’ve not given a great deal of attention to the capabilities of the on-board PMIC device, so go with @RWB’s advice on it, @dcliff9. Cheers, AT
Hi I am seeing similar strange charging inconsistencies with my solar powered Electrons. I am using these 6V solar panels, do you think I need to set a minimum input voltage? The datasheet lists the max voltage at 4.69V.