LiPo monitoring

[David118309]

Apologies if this topic has been covered elsewhere but I couldn’t find a total answer.

Since letting a LiPo totally discharge is not a good idea, the Adafruit MAX17048 fuel guage seems to be a good idea to incorporate into a project that uses the 2000mAh battery / LiPo expansion for Pico.

The current project is using the PiicoDev_Unified library along with the SSD1306 large font and works well. The Max17048 runs from I2C with CircuitPython, so not exactly sure how to get the two sections to talk to each other.

From the Adafruit site the path seems to be CircuitPython / Blinka / Adafruit u2if fork?

Any thoughts welcome thanks.

[Michael]

@David118309

From the Adafruit site the path seems to be CircuitPython / Blinka / Adafruit u2if fork?

Hi @David118309 - you’re correct! The adafruit fuel gauge will run on CircuitPython, but he PiicoDev OLED uses MicroPython.

Luckily, the OLED uses a SSD1306 driver IC, so if you can find a CP driver for this device you’re in the clear!

Here’s one I found that looks promising: CircuitPython SSD1306

Bear in mind you may need to check the OLED default address to initialise it correctly - check the product page for more information.

[David118309]

Thanks Michael for the link. Looks like I will have to go down the Blinka route to get this going as PiicoDev.py: Unifies I2C are drivers for different builds of MicroPython.

But experimentation is half the fun.

In the meantime, how do I tell how much charge is in the LiPo? does it come from Core 1/2 or 3/4 charged? If I plug it into the LiPo expansion board, how long can I leave it connected?

Thanks

[Aaron]

Hi @David118309,

@David118309

how do I tell how much charge is in the LiPo?

The best way to check LiPo charge level is with a simple voltage check.
Typically 4.2V is fully charged, 3.8v is the optimal voltage for long-term storage and completely discharged is 3V though I typically air on the side of caution when discharging and only go to 3.4V or 3.2V as an extreme.

@David118309

does it come from Core 1/2 or 3/4 charged?

I checked the voltage of one of our LiPo’s on the shelf and it was at 3.95V.

@David118309

If I plug it into the LiPo expansion board, how long can I leave it connected?

Not entirely sure about the question here.
You will know the battery is charged when the LED on the board turns off. How long it will take depends on the battery capacity.

I hope this helps answer your questions though.

[David118309]

Thanks Aaron, yes that helps a lot and gives me something to keep checking.
Cheers