Today i will show you the Battery Capacity Meter Discharge Tester | Battery Tester.

This schematic i found on internet with the AVR code. I try to make the PCB by Eagle software and order PCB online on https://jlcpcb.com/. After that the circuit work great and i share it for you. i hope you can do it at home

Step 1: Watch This Video From Youtube

At this video, i show to you the schematic and code for AVR on description. I order PCB and make it complete after that i test it with my old 12V battery. And it work great. i hope you can do it

Step 2: Make the Schematic

This schematic i found on internet and i try to make it with Eagle software. The main IC is Atmega 8. you can download the code for Atmega 8 here. This schematic works great

Step 3: Order the PCB Online With JLCPCB.COM

I make the gerber file by Eagle software and upload them to https://jlcpcb.com/ for order PCB online.

Only 2$ /10pcs for 2 layer PCB and Big Discount on First order Shipping

https://jlcpcb.com/ Upload your gerber files and fill in Shipping Adress then click PAY.

After 2 day. I received the PCB 10PCS it look great and beauty.

Step 4: Order the Component,Solder PCB and Finish

This is the list of part:

Capacitor 22uF/35V.

Capacitor 470uF/10V.

4x Capacitor 104/50V.

Capacitor 103/50V.

LM7805.

LED Display 7 Segment 4 Digit 0.56 inch Common Anode.

8 x 560 ohm resistor

Krystal 32768HZ

Atmega8A

3 button 2 pin

1 led 3V

1 kilo ohm resistor

2x diode 1n4148

220 kilo ohm resistor

47 kilo ohm resistor

22 kilo ohm resistor

1 uF/50V capacitor

0.22 ohm 5W resistor

1 IRF3205 Fet

270 ohm resistor

33 kilo ohm resistor

3.15A fuse.

50 kilo ohm potentiometer

20 kilo ohm potentiometer

10 kilo ohm potentiometer

IC MC33171.

How to control

Control:The battery meter is controlled with buttons Mode, "+" and "-". Mode button switches six display states: • 1) Display the actual voltage (0.00 V - 20.4 V). • 2) Measured energy in Wh (Watt hours). Displays "En" symbol and then the value. During the discharging process it increments. After the discharge is finished, it shows the result. • 3) Measured capacity in Ah (Ampere hours). Displays the "Ah" symbol and then the value. During the discharging process it increments. After the discharge is finished, it shows the result. • 4) Elapsed discharge time in hours (0.00h - 655h). • 5) Desired discharge current. Use the + and - to select from 0.01 A to 2.56 A. • 6) The selected end voltage. Use the + and - to select the voltage at which the discharge process is terminated (range from 0.80 V to 20.0 V). Pressing "-" in steps 2, 3 and 4 you can reset the energy, capacity and time values (it only works if the discharge process is not active). Long press of the Mode button starts or stops the discharging process. When discharging process is active, LED1 is on. After the LED1 turns off, you can read the measured data (energy, capacity, time). Before a new measurement you need to reset the data. (The data are not automatically reset at the beginning of the discharge and measurement process. This allows you to resume an interrupted measurement.) The end voltage is usually chosen around 0.9 - 1V for NiCd and NiMH, 3 - 3.4 V for Li-Ion and Li-Pol and 9-10 V for lead-acid batteries.