MAX17043 LiPo Fuel Gauge
I2C battery fuel gauge that reports accurate state-of-charge — far better than voltage guessing.
A single-cell fuel-gauge IC that reports accurate state-of-charge over I2C, far more reliable than estimating from raw voltage. Rather than just reading the battery's terminal voltage (which sags and recovers unpredictably under varying load), the MAX17043 uses a proprietary ModelGauge algorithm to track the cell's actual state of charge over time, giving a genuinely useful percentage reading for battery-powered projects — wearables, handheld devices, or anything that wants to show a realistic 'battery remaining' indicator rather than a rough voltage-based guess.
Specifications
| Chipset | Maxim MAX17043 single-cell Li-ion/LiPo fuel gauge |
| Operating voltage | 3.0V–4.2V DC (matches a single Li-ion/LiPo cell's voltage range directly) |
| Operating current | ~50 µA typical, very low quiescent draw suitable for always-on battery monitoring |
| Measurement | State-of-charge percentage (0-100%) via Maxim's ModelGauge algorithm, plus raw cell voltage |
| Accuracy | No characterization or calibration required — works out of the box across most standard Li-ion/LiPo chemistries |
| Interface | I2C, up to 400 kHz |
| I2C address | 0x36 (fixed) |
| Additional feature | Configurable low-battery alert via an interrupt output pin |
Pinout
| Pin | Name | Description |
|---|---|---|
| 1 | VDD | Power, 3.0–4.2V DC (typically wired directly to the same single-cell battery being monitored) |
| 2 | GND | Ground |
| 3 | SCL | I2C clock line |
| 4 | SDA | I2C data line |
| 5 | ALRT | Low-battery interrupt output, configurable threshold |
| 6 | QSTRT | Optional quick-start pin to force an immediate state-of-charge recalculation |
This chip is specifically designed for single-cell (1S) Li-ion/LiPo batteries only and reads the cell voltage directly through its VDD pin rather than through a separate sense input, so it should be wired directly across the battery terminals (not through a regulator) for accurate readings; the ALRT pin can be used to trigger a low-battery warning or safe shutdown in software.
Variants
Use the MAX17043 whenever a project needs a genuinely trustworthy 'percentage remaining' battery indicator rather than a rough estimate — the ModelGauge algorithm accounts for the nonlinear discharge curve that a simple voltage reading misses entirely. A plain voltage-divider read is fine only for a rough 'battery is getting low' warning where precision doesn't matter.
| Variant | Temp range | Hum range | Accuracy | Protocol | Price |
|---|---|---|---|---|---|
| MAX17043 breakout | ~$3-6 | ||||
| MAX17048/MAX17049 | ~$4-8 | ||||
| Simple voltage divider + analogRead() | ~$0 (uses existing resistors) |