Adafruit MAX17048 LiPoly / LiIon Fuel Gauge and Battery Monitor - STEMMA JST PH & QT / Qwiic (ADA5580)

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Does anyone know if this product can be linked to a 18650 BMS of three cells (~11-12V). Looking at the example code it looks like there isn’t an obvious way of setting initial voltage or current, but it could detect it I guess.

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Hi Aaron,

This monitor is just for the one cell, and is worth noting its just a fuel gauge not a fully featured BMS (doesn’t offer any kind of protection).

There are dedicated IC’s that would do this job, though a bit more outside of the Maker market.

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Hey Liam, yea I get that :slight_smile: was thinking of using the CE09207 BMS, but as far as I can tell that doesn’t have a fuel gauge. I want some sort serial output to let me know how much charge the battery has. Would love it if you could recommend a solution.

Suppose you could use three of the MAX17048, and add the result together, but not even sure if that would work. It looks it connects to serial communication, so would image that you could only use one of them at a time.

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Hey Liam, not sure if I am reading this post correctly, Feul Gauge and Protections for Multiple 18650 Cells in parallel connections - Power management forum - Power management - TI E2E support forums

but what it sounds like to me is that the fuel gauge is hooked up to one 18650 cell, assuming hooked into the BMS, and using that to approximate the usage across all cell.

Guess that could work if all the batteries are relatively the same, does that sounds right to you?

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Hi Aaron,

Unfortunately not, but what bang for your buck that would be.

Nothing rings a bell off the top of my head, you could try hacking this alarm module: LiPo Voltage Tester and Buzzer | Core Electronics Australia
I have little experience other than the intended use case.
Otherwise, differential ADCs or a dedicated IC as mentioned:

The module actually uses I2C, which can be setup with multiple devices.
BUT the problem arises when trying to measure the other cells, the GND pin of the first cell, bridges Vbatt1, the second module GND is connected to Vbatt1 - shorting out the battery :frowning:

From a quick glance at the link they have 3 batteries in parallel, very different to series.
In parallel, the sum will act as one higher capacity, so we can measure the total charge of the pack.
Your setup has 3 in series, increasing the voltage - different story unfortunately.

Dialling things back a bit, whats your overall project? Is there a reason you need to monitor each cell?

A bit tangential but perhaps not. For larger batteries I normally use a voltage divider and a microcontroller. Just pick your resistances so you don’t fry your board and with a bit of maths you can get a voltage.

But as Liam asked, with some more info about your project we can work towards what’s best for you!

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