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020 NiMH Battery Charger

akbar-q·Circuits-PCB-HardwareDesign·NiMH Battery Charger/020 NiMH Battery Charger.kicad_pcb

020 NiMH Battery Charger PCB layout, top view — open source ESP32 board by akbar-q

About the 020 NiMH Battery Charger PCB

020 NiMH Battery Charger is an open source ESP32 PCB design by akbar-q, published on GitHub. It is a 2-layer board measuring 100 × 72.8 mm, with 82 components from 20 distinct parts.

Its main chip is the ESP32-WROOM-32D, from the ESP32 family. Other key parts include the LM317_SOT-223, LM337_SOT223 and D168K. By type, the board carries 32 resistors, 25 diodes, 8 capacitors, 5 battery holders, 4 ICs and 1 connector.

It belongs with the power & battery and iot & wireless designs in this gallery.

From the project

Instead, the current design relies on voltage measurements. When no battery is connected, the voltage at the ADC input is nearly 3V. When a battery is plugged in, the voltage drops to a lower value due to the resistor at the battery's positive terminal. If the battery voltage exc

Instead, the current design relies on voltage measurements. When no battery is connected, the voltage at the ADC input is nearly 3V. When a battery is plugged in, the voltage drops to a lower value due to the resistor at the battery's positive terminal. If the battery voltage exceeds a certain threshold, it is determined to be nearly fully charged. At this point, a timer can be started to wait for the battery to reach full charge.

Main components on the 020 NiMH Battery Charger

LM317_SOT-223ESP32-WROOM-32DLM337_SOT223D168K

020 NiMH Battery Charger bill of materials (BOM)

82 components, 20 distinct parts — part numbers from the project's BOM.

QtyPartRefs
1
LM317_SOT-223
AMS1117-3.3
U1
1
ESP32-WROOM-32D
U2
1
LM337_SOT223
AMS1117-3.3
U3
1
D168K
U4
1
USB_C_Receptacle_PowerOnly_6P
J1
2
SW_Push
BOOT1, RESET1
5
AA
BT1, BT2, BT3, BT4, BT5
1
Conn_01x06_Pin
FLASH1
4
Conn_01x06_Pin
LedIn1, LedOut1, SenseOut1, SesnseIn1
5
LED
D1, D2, D3, D4, D5
15
ESD9B5.0ST5G
D6, D7, D8, D9, D10, D11, D12, D13 +7
5
Diode
D21, D22, D23, D24, D25
7
2.2U
C
C1, C2, C3, C4, C6, C7, C8
1
100N
C
C5
5
680R
81R
R1, R2, R3, R4, R5
3
680R
10k
R6, R7, R10
2
680R
R
R8, R9
5
680R
51R
R11, R12, R13, R14, R15
9
10k
R23, R24, R25, R27, R36, R37, R38, R39 +1
8
1k
R28, R29, R30, R31, R32, R33, R34, R35

020 NiMH Battery Charger design files

The KiCad project lives in the akbar-q/Circuits-PCB-HardwareDesign repository on GitHub; these links point at the commit this page was built from.

020 NiMH Battery Charger: common questions

What microcontroller does the 020 NiMH Battery Charger use?

The 020 NiMH Battery Charger is built around the ESP32-WROOM-32D, from the ESP32 family.

How big is the 020 NiMH Battery Charger PCB?

The 020 NiMH Battery Charger measures 100 × 72.8 mm, has 2 copper layers and is 1.6 mm thick.

How many components are on the 020 NiMH Battery Charger?

82 components, from 20 distinct parts, with part numbers taken from the project's own BOM. The full bill of materials is listed on this page.

Where can I download the 020 NiMH Battery Charger design files?

From the akbar-q/Circuits-PCB-HardwareDesign repository on GitHub, which has the KiCad layout, the schematic and the BOM; the links under Design files point to each one.

Can I use the 020 NiMH Battery Charger design in my own project?

The repository has no license, so all rights stay with akbar-q. Use it as a reference, and ask the author before reusing the design.

Can I test firmware for the 020 NiMH Battery Charger without the hardware?

Yes. HardLabs builds a simulation of the board from its netlist and BOM, so you can run and debug ESP32 firmware against it before you order a PCB.

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