Project guidance request ("pass through" charger/ups)

I would like to design a “pass through” charger with optional solar input for 4 18650 cells. The load will be a raspberry Pi with some number of USB connections.

-If external power is connected, battery should continue to charge while powering the load

-If external power is disconnected, it should switch to battery power without current or voltage drop.

What IC/devkits should I look at? Max budget is about $50.

Many thanks in advance


Welcome to the forum.

The Waveshare Raspberry Pi UPS HAT has schematics and IC data sheets for their design on their Wiki.

I tend to just buy low end APC & CyberPower UPS’s designed to run a high power PC and use them for multiple Pi’s to save money.

If I needed to save space, I’d try out the Waveshare product.

There are many discussions of this topic at the Raspberry Pi forum.

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I looked into this. For a variety of reasons, I’m not really interested in a hat.

Furthermore, I recently purchased from WaveShare. My experience was not positive.

However, I will review their wiki to see if I can find anything else useful.

How much wattage do you need?

These are fun to play with:

More info: "Solar Power Manager


Yeah, I remember these guys. They are pretty awesome, I’m glad they made it to DigiKey. Not sure it will work in my application, will read more.

Thanks so much!


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