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This board forms part of a 9 * 18650 battery charger using 3 INA3221 chips to capture the voltage/current during charging. The I2C INA3221 register data is written via the WEMOS PRO MINI to an INFLUX database every 10 seconds. The data is surfaced through a GRAFANA dashboard. Each INA3221 has its own I2C address hardwired through links to the A0 pin i.e. (0x40, 0x41, 0x42) More information on the INA3221 can be found in the datasheet The other main components are 9 TP5000 charging modules and a buck converter supplying the overall power to the converters.

Screen capture only showing 6 batteries for clarity, but you get the gist of it. Capture.PNG

Capturing this data may appear overkill for non data junkies.

I will post the complete design, and would appreciate anyone willing to QA future designs before fabrication.

Sample code base on Github


INA3221 Charger Board V1.1




ID Name Designator Footprint Quantity
1 INA3221_RGV_16 U2,U3,U4 RGV16_2P16X2P16 3
2 WJ126V-5.0-6P P1,P2,P3 WJ126V-5.0-6P 3
3 0.1Ω R2,R15,R16,R1,R17,R18,R19,R26,R27 2512 9
5 10Ω R5,R6,R11,R12,R13,R14,R3,R4,R7,R8,R9,R10,R20,R21,R22,R23,R24,R25 2512 18
6 1uF C1,C4,C5,C2,C3,C6,C7,C8,C9 0603 9
7 210S-1*3P H1,H2,H3 210S-1X3P 3
8 210S-1*10P H6,H7 210S-1X10P 2
9 LTST-C930KGKT Green LED2 LED-1209 1
10 LTST-C930KRKT Red LED4 LED-1209 1
11 100Ω R30,R28 1206 2




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Comments (4)

tokio69 Reply

Great work !
do you have a website or blog or anything where I can follow your work?
I have been looking for a nice piece of PCB to charge and test many 18650 batteries.
Greetings from belgium

grahamob Reply

Hi Tom,
Thanks for you comments. I dont have a blog or website, but would be very happy to answer any questions if you need furthur information on the battery charging project.

tokio69 Reply

@grahamob hi. I have been looking arround some stuff and still come back to your design witch is great.
i want to build a super multi 18650 testing station and be able to do capacity test on each cell and keep values in a data base. if possible for 64 cells. Cycle in auto start or something.
Is there any progress on the design or software?

grahamob Reply

Been very busy on my new BMS design recently, but thanks for the positive comments.
You can find the ESP8266 charging data code on my GitHub repository
I quite like the sound of taking the original concept to do full charge/discharge and capacity capture.
It should not be a great stretch to modify the design, and I will rip the case off my Zanflare C4 at the weekend to see how a commercial battery tester is designed.
I will drop you a note to let you know my findings,

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