I'm trying to power up an ESP-01 with a Li-ion battery pack recharged by a solar panel (12 V).

The question is: can I connect the solar panel directly to the battery pack with a voltage regulator, or do I need something else as protection?


1 Answer 1


A voltage regulator on its own won't do.

In short, you need a proper Li-ion charger with load-sharing, preferably with some form of Maximum Power Point Tracker to get the most out of your solar panel.

It is also advisable to add a Battery Management System to your battery pack, if it doesn't already have one, if only to make sure the batteries don't discharge too far.

ICs and modules exist that can do all or most of that. We don't do product recommendations here, but with the search terms above you should be able to find integrated solutions.

Li-ion batteries need to be charged with a specific algorithm (constant current first, then constant voltage, until the current has dropped below a certain value). A voltage regulator can't do all that.

You need load-sharing because the charging algorithm won't work properly when a load is connected directly to the battery.

You may need a form of MPPT because the solar panel won't deliver its full power otherwise, if it is not well-matched to the battery.

  • \$\begingroup\$ What is MPPT? and BMU? (Battery Management Unit?) \$\endgroup\$
    – Holmez
    Feb 3, 2021 at 11:59
  • 1
    \$\begingroup\$ Maximum Power Point Tracker, Battery Management Unit/System. \$\endgroup\$
    – ocrdu
    Feb 3, 2021 at 12:03

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