I have the following setup; 20v solar panel -->> MPPT chagre controller (sparkfun sunny buddy) -->> battery(3.7v 7000mAh & 5v microcontroller in parallel, see diagram below.

In full sunlight and approx. 19v input to the charge controller from the solar panel;

  1. Should there be power applied to both the battery and the microcontroller?
  2. If the battery is low ( i.e. charging ) will the microcontroller still get power?

Thank you.


simulate this circuit – Schematic created using CircuitLab


You need a proper charge controller for the battery, and a suitable voltage regulator (probably DC-DC converter) to provide power to the Pi.

Both devices must be designed to operate from the voltage provided by the MPPT controller.

  • \$\begingroup\$ The MPPT controller IS a DC-DC convertor and charge controller. \$\endgroup\$ – Jack Creasey Apr 9 '17 at 16:14
  • \$\begingroup\$ I have a voltage regulator at the Raspberry Pi \$\endgroup\$ – Tullio_IRL Apr 9 '17 at 16:43
  • \$\begingroup\$ What I'm trying to understand is how voltage from the controller is divided between the battery, when it's charging, and the load ( microcontroller ), does the load get its power from the battery along or can it get it from the controller when available? \$\endgroup\$ – Tullio_IRL Apr 9 '17 at 16:45

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