MicroPowerCore
Ultra-low-power boards for ESP32 Shipping from Germany Datasheet and test method published

Power module · rev 1.2 · 33 × 12 mm

MicroPowerCore v1.2 Li-Ion/LiPo charger and 3.3 V buck-boost board for ESP32

LiPo in · 3.3 V out · 17–18 µA in between

One board charges a single Li-Ion/LiPo cell and holds a regulated 3.3 V rail up to 1 A while the cell runs from 4.2 V down to 3.0 V.

Order from €16.00 Compare both boards

17–18 µA: whole module, no load, not charging.

EXT_PWR 4.5–5.5 V in ACCUM one cell, 3.0–4.2 V 3V3 3.3 V out, up to 1 A 33 12 TOP VIEW · DIMENSIONS IN mm TERMINAL POSITIONS INDICATIVE · FOOTPRINT AND POLARITY: SEE DATASHEET
Part · revision
MicroPowerCore v1.2
Cell
1 × Li-Ion/LiPo, 3.0–4.2 V
Input · output
4.5–5.5 V → 3.3 V, up to 1 A
Charge
300 / 500 mA, 10 h timer
Quiescent current
17–18 µA
Datasheet
PDF, 3.4 MB ↓

Standby current · bill of materials

What a sleeping ESP32 node draws

Measured at the board input on our bench. The method is in the hibernate guide.

ItemPartStateCurrent
1DeepSleep dev board, ESP-WROOM-32Hibernate, RTC timer only4.9–5 µA
2MicroPowerCore v1.2No load, not charging17–18 µA
ΣNode before sensorsBoth boards in hibernate≈22–23 µA
—For comparison: typical ESP32 dev boardDeep sleep, USB-UART bridge, LED and LDO powered0.1 mA – several mA

Boards

2 parts · sold separately · designed as a pair
MicroPowerCore v1.2 board, angled view of the charger and buck-boost components

Power module · rev 1.2 · 33 × 12 mm

MicroPowerCore v1.2

Single-cell Li-Ion/LiPo charger and 3.3 V buck-boost converter on one board. The load keeps running while the cell charges.

Cell
1S, 3.0–4.2 V
Input
4.5–5.5 V
Output
3.3 V, ≤ 1 A
Charge
300 / 500 mA
Quiescent
17–18 µA
Board
2-layer PCB
Datasheet · PDF, 3.4 MB Technical details ↓ Questions and answers ↓
Where to buy
Continue to Lectronz ↗ Continue to Tindie ↗

Ships from Germany · delivery & returns

MicroPowerCore v1.2 board next to a millimetre ruler
33 × 12 mm against a ruler
MicroPowerCore v1.2 wired to a USB-C supply and a LiPo cell with the charge LEDs on
USB-C supply on EXT_PWR, cell on ACCUM
MicroPowerCore v1.2 board mounted on a LiPo pouch cell
Mounted on a LiPo pouch cell
Multimeter reading 16.8 µA DC on MicroPowerCore v1.2
Bench reading: 16.8 µA DC
DeepSleep dev board with ESP-WROOM-32 module, top view

ESP32 dev board · ESP-WROOM-32 · 29 × 39 mm

DeepSleep dev board

A minimal ESP32 board for microamp-level sleep experiments. No USB-UART bridge, no power LED, no LDO: feed it a regulated 3.3 V.

Module
ESP-WROOM-32
Supply
3.3 V on VIN
Hibernate
≈5 µA measured
Input caps
22 µF + 0.1 µF
Flashing
USB-UART at 3.3 V
Boot
Manual BOOT + RESET
Flashing guide Schematic Board details →
Where to buy
Continue to Lectronz ↗ Continue to Tindie ↗

Ships from Germany · delivery & returns

Typical application · connections

Wire them together

Three connections and no extra parts. This pair is the bench behind the measurements in our hibernate guide.

FromToTerminalVoltage
USB 5 V or adapterMicroPowerCore v1.2EXT_PWR4.5–5.5 V
One Li-Ion / LiPo cellMicroPowerCore v1.2ACCUM3.0–4.2 V
MicroPowerCore v1.2DeepSleep dev board3V3 → VIN3.3 V

Check polarity against the silkscreen and the datasheet before connecting the cell.

MicroPowerCore v1.2

Technical details

What is on the board and why it is built this way.

Design philosophy

The core idea behind MicroPowerCore is simplicity and reliability in a small form factor. Measuring only 33 × 12 mm, the board integrates the Texas Instruments BQ24xxx battery management IC and the TPS63xxx buck-boost converter to keep performance consistent across a range of conditions.

MicroPowerCore v1.2 board layout with the EXT_PWR, ACCUM and 3V3 terminals

Battery management

The BQ24xxx IC manages the charging process for single-cell LiPo batteries. With built-in safety features, it prevents overcharging and extends the battery’s lifespan. Two onboard LEDs show external power and the charging state.

Buck-boost conversion

The TPS63xxx keeps a stable 3.3 V output regardless of the battery’s charge state. Whether the input voltage is higher or lower than the required output, the converter adjusts to provide consistent power to connected microcontrollers and sensors.

Technical challenges and solutions

  • Voltage fluctuations: battery voltage varies during operation; the buck-boost converter keeps the 3.3 V rail stable through the whole discharge.
  • Compact design: the integrated ICs fit charging and regulation into a 33 × 12 mm board for space-constrained projects.
  • Energy efficiency: 17–18 µA of quiescent current makes the board suitable for long-term, battery-operated devices.

Applications

  • Battery-powered ESP32 and 3.3 V Arduino projects (Pro Mini 3.3 V and similar; not the 5 V Uno)
  • IoT devices and remote sensors
  • Sensor systems with extended autonomy
  • Robotics and embedded systems
  • Portable and wearable devices with a 3.3 V microcontroller

ESP32 sleep modes and battery power

Guides

All low-power guides →
ESP32 hibernate mode: 5 µA with the RTC timer only What stays powered, which wake-up sources survive, and how we measured 4.9–5 µA on the DeepSleep dev board. Sleep modes 4.9–5 µA 15 min

MicroPowerCore v1.2

Questions and answers

QWhich batteries can MicroPowerCore charge?
One Li-Ion or Li-Po cell in the 3.0–4.2 V range. Multi-cell packs and LiFePO4 cells are not supported. The charge current is 300 mA by default or 500 mA with the jumper, and the charger has a fixed 10-hour safety timer, so very large cells (4000 mAh and more) may not complete a full charge in one cycle.
QCan my ESP32 keep running while the battery charges?
Yes. The system load is connected in parallel with the battery, so the 3.3 V output stays up while VIN is present. Current drawn by your circuit reduces what is left for the battery, so charging takes longer under load.
QIs 1 A enough for an ESP32 with Wi-Fi?
Yes for ESP32-class modules: their Wi-Fi and Bluetooth transmit bursts are in the hundreds of milliamps (see the Espressif datasheet), within the 1 A output. Keep a bulk capacitor close to the module to absorb the peaks; our DeepSleep dev board uses 22 µF.
QHow is this different from a TP4056 module plus a boost or buck converter?
A TP4056 board only charges the cell; you still need a separate regulator, extra wiring, and every added board adds its own quiescent current. MicroPowerCore combines the charger and a buck-boost converter on one 33 × 12 mm board with a total no-load current of 17–18 µA, and the buck-boost holds 3.3 V across the whole 3.0–4.2 V cell range instead of dropping out when the cell voltage falls.
QWhat is the quiescent current and why does it matter?
17–18 µA is what the whole module draws with no load and no charging: charger plus buck-boost. In a sleeping IoT node this overhead is often larger than the microcontroller itself (an ESP32 in hibernate draws about 5 µA on our DeepSleep board, see the hibernate guide), so the power board decides the standby budget.
QCan I get 5 V or another output voltage?
The board ships configured for 3.3 V, the native voltage of the ESP32 and most 3.3 V sensors. The output is set by a feedback resistor, so other voltages are possible for experienced users, but 3.3 V is the only configuration we test and document.
QCan I charge from a solar panel?
Not directly. VIN must stay within 4.5–5.5 V, and even a small 5 V or 6 V panel exceeds that when lightly loaded, so a 5 V regulator would be required between the panel and the board, and that regulator's own consumption has to be added to the standby budget. We have not measured or documented a solar setup and do not recommend one yet.