Please design an Arduino with a built in LIPO charger with a battery disconnect feature

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#1

Hey everyone. I want to bring this up for discussion:

TL;DR: Why is there no Arduino with a built-in lipo charger with a battery disconnect feature? I think this would be a huge seller since literally, no one is making this.

This seems super useful for wearable electronics. The Lilypad USB is the closest thing to this but it lacks a lipo disconnect feature when the battery voltage drops below 3v. This is a fatal flaw since a lipo battery that is fully discharged will have about 10 cycles of use.

The Arduino doesn’t even need to be that fancy since the people in the wearable tech space tend to mostly need simple features like reading an analog sound sensor, reading an accelerometer or light sensor and writing out LED data. An 8 bit 328p or 32u running at 8Mhz seems totally appropriate for this use case and the low power code is readily available to shut the chip down to using microamps of power.

Ideally, an Arduino type like this could be round and designed to an LR3032, LR2032, LR2450, or similar lipo battery with 120mA capacity (higher capacity can present temperature problems if the battery shorts), which can be directly soldered onto the board. Or the Arduino could be rectangular like the Arduino nano and glued onto a matching LIPO pouch cell.

This seems like a huge win: cheap, readily available using no fancy parts, and super useful. Right now I have to buy a discrete LIPO charger from Amazon and glue it onto an Arduino Nano. The big problem too is that the LIPO chargers on Amazon are designed for 1A charging for those large cylindrical LIPO batteries, requiring manual re-work to add a resistor. I just want something that has 50-100mA of max charge current to keep everything small. Also, the FTDI chip on this Arduino should not draw the 4mA or so in idle mode like some web tutorials warn about.

Has this ever been brought up for discussion? I can’t believe that so many videos have been produced about the topic of wearable electronics yet we still don’t have a reasonable Arduino solution like this which doesn’t absolutely wreck the attached LIPO battery.

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#2

Hi there, Zackees
We are all in that boat, battery wise. Crazy all the Claims of Battery operation and you can’t properly read or manipulate charge currents etc, including disconnect. I believe they rely on the BMS in the battery.
I’m using this setup to test something with wifi, but needs battery management to be reliable.
HTH
GL :slight_smile:
PJ

B-1
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#3

The only escape hatch that I’ve found is that a certain subset of a lipo pouch cells actually do contain an undervoltage lockout feature. Unfortunately, most of them are set at 2.75-2.85 volts, which wrecks the battery if not immediately recharged and instead put into storage.

So an even smaller subset have undervoltage lockout AND it’s set at 3.0v.

Adafruit got back to me and let me know that they have pouch cells that cut off the current at 3.0v, which is at the limit, according to battery nerds. The better option is cutting off at 3.1v. Below that some sort of weird irreversible chemical reaction takes place. But I haven’t found batteries that have this level of lockout.

What’s weird is that all this work on video content has been produced about wearables, yet this battery solution, which would take an electrical engineer one day to do, hasn’t been done. It’s mind-blowing. Someone just needs to solve this problem so we can have cool wearables that don’t require giant disposable cylindrical cells.

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#4

I second this. It’s been years…