ET-S40
MAX17048 LiPo Fuel Gauge
Battery percentage over I²C, JST-PH pass-through
AED 19.00
Out of stockOverview
Battery percentage over I²C, JST-PH pass-through
The ET-S40 is built around the Maxim MAX17048 — ModelGauge (no sense resistor), SOC % and voltage, 1% SOC resolution, 23µA active / 3µA hibernate. It connects over I²C fixed 0x36 and is powered from The IC runs from the battery. VIN (Qwiic) is used only for I2C pull-ups.
Two Qwiic / STEMMA QT connectors let you chain it with other boards without soldering, and the 2.54 mm header fits a breadboard.
Designed in Dubai by ElectroTrical — the full schematic, BOM and design notes are published below.
Good for
- Battery percentage on wearables
- Low-battery shutdown
- Remote sensor nodes
Key features
What makes it different
IC
Maxim MAX17048: ModelGauge (no sense resistor), SOC % and voltage, 1% SOC resolution, 23µA active / 3µA hibernate
Interface
I2C fixed 0x36
Battery
1-cell Li-ion/LiPo 2.5–4.5V on JST-PH 2mm, pass-through to the load
Supply
The IC runs from the battery. VIN (Qwiic) is used only for I2C pull-ups
Qwiic / STEMMA QT
Two JST-SH connectors plus a 2.54 mm header — 3.3 V and 5 V hosts.
Open documentation
Schematic, BOM and layout notes published for every board.
Specifications
Technical specifications
| IC | Maxim MAX17048: ModelGauge (no sense resistor), SOC % and voltage, 1% SOC resolution, 23µA active / 3µA hibernate |
|---|---|
| Interface | I2C fixed 0x36 |
| Battery | 1-cell Li-ion/LiPo 2.5–4.5V on JST-PH 2mm, pass-through to the load |
| Supply | The IC runs from the battery. VIN (Qwiic) is used only for I2C pull-ups |
| Size | 25.4 × 17.8 mm |
|---|---|
| Mounting | 4 × M2.5 holes, 2.54 mm from each corner |
| Connectors | 2 × Qwiic / STEMMA QT (JST SH 4-pin) · 5-pin 2.54 mm header · JST PH 2P R/A SMD (LiPo) — Battery in (LiPo) · JST PH 2P R/A SMD (LiPo) — Battery out to load / charger |
| Main IC | MAX17048G+T10 (LCSC C2682616) |
| Revision | Rev B |
| Libraries | Adafruit_MAX1704X / CircuitPython, SparkFun MAX1704x, ESPHome max17043-style (check) |
|---|
| JP1 (default Closed) | Cut to turn off the LED |
|---|---|
| JP2 (default Closed) | Cut to remove the host-side I2C pull-ups |
Performance
Power draw by mode
Pinout
Pin map and connections
| Pin | Name | Type | Function |
|---|---|---|---|
| 1 | VIN | Power | Sensor supply = host logic level |
| 2 | GND | Ground | Ground |
| 3 | SCL | I²C | I²C clock |
| 4 | SDA | I²C | I²C data |
| 5 | ALRT | Signal | Low-SOC / reset alert, active low |
Qwiic / STEMMA QT pins: GND, VIN, SDA, SCL (same on both connectors). I²C pull-ups (10 kΩ) are on the board; cut JP2 to remove them.
Mechanical
Dimensions and what's in the box
In the box
- 1 × ET-S40 MAX17048 LiPo Fuel Gauge (assembled)
- 1 × 5-pin 2.54 mm male header, unsoldered
Getting started
- Plug in a Qwiic / STEMMA QT cable, or solder the header and wire VIN, GND, SDA and SCL
- Libraries: Adafruit_MAX1704X / CircuitPython, SparkFun MAX1704x, ESPHome
max17043-style (check) - Run an I²C scanner to confirm the address: 0x36
Compare
Which current and power board?
| MAX17048 LiPo Fuel Gauge (this board)This board | ET-S07 INA228 85 V Power Monitor | ET-S37 ACS725 ±20 A Current Sensor | ET-S38 2-Channel CT Clamp Interface | |
|---|---|---|---|---|
| What it does | Battery percentage over I²C, JST-PH pass-through | 20-bit current, voltage, power and energy monitor | Isolated Hall current sensor with 16-bit I²C ADC | SCT-013 clamp interface with 16-bit I²C ADC |
| Interface | I²C fixed 0x36 | I²C 0x40 default; 0x41/0x44/0x45 via JP3/JP4 (16… | I²C 0x48; raw analog VIOUT also on J3.6 | I²C 0x48 |
| Best for | Battery percentage on wearables | Battery and solar monitoring | Motor current monitoring | Home energy monitoring |
| Price | 19 AED | 59 AED | 49 AED | 49 AED |
Downloads
Documents and design files
Need a custom version of this board?
Different connector, size or sensor? We design and build custom variants.