/Schematics/Power supply/Smart battery tester and charger

I started off this device to be a simple meter of internal resistance of mobile phone batteries but over time it became a bit more complex project. It is based on PIC16F88 microcontroller.

You can download the entire project files (schematics, hex file for PIC16F88) by clicking on red download button at the end of the article.

UPDATE 04-26-2011: New firmware is added to the .rar archive (the red download button). Some bugs fixed (read the CHANGELOG.txt file from the .rar archive).

UPDATE 05-15-2011: New firmware is added to the .rar archive (the red download button). Some bugs fixed (read the CHANGELOG.txt file from the .rar archive).

UPDATE 07-07-2011: New firmware is added to the .rar archive (the red download button). Some bugs fixed (read the CHANGELOG.txt file from the .rar archive).

UPDATE 01-30-2012: New firmware is added to the .rar archive (the red download button). Few changes made (read the CHANGELOG.txt file from the .rar archive).


So, now we have these capabilities: battery charging, discharging, measuring internal resistance of batteries and measuring capacity of Li Ion, Li Po, Ni Cd, Ni MH as well as regular (non rechargeable 1.5V cells). This device is fully automated so we can leave it overnight to fully discharge the battery, charge it, measure capacity and show on display.

In case of power supply loss, charger will remember how much it charged battery already and will continue after that point. This will prevent over-charging.


You can also force stop the charging process and start discharging from that point or continue charging. Charging of Li Ion and Li Po is done in two steps; first it will charge to 4.3V per cell and then continue pulsed-charge and hold the voltage on 4.25V so that the battery voltage is being measured without the presence of charge current. Discharging cells for the purpose of measuring capacity is done until 3V per cell. Capacity is measured during charging so we can know how much mAh the battery has accepted. Termination of charge in Ni MH and Ni Cd batteries is done with "delta T" method, where if the temperature rise is more than 1.5 degrees Celsius per minute it means the battery is full and charging will stop. There is also a fail-safe mechanism that will prevent overcharge when thermometer fails. In that case, the cut-off voltage is 1.6V per cell. Discharging of this kind of batteries goes until 1V per cell.


The purpose of testing 1.5V cells is to know the quality of the batteries that we purchase - we shouldn't just trust commercials that we see.

There are two PCB drawings for this device. One of them is for LM2575 which is easier to find, and a 330µH coil must be used with it.


[ Source: E. Lelic ]

Author (sent by): E. Lelic

Download counter: 8,755

Rating: (2.91, votes 1963)


Date: 14-04-2011

Lokalna verzija ove stranice: Pametni tester i punjač baterija


Bookmark and Share Comments (41)

comment [11]

or send me a datasheet for lm2959 and irf7341 or please find it on page http://uk.farnell.com/ this because I bought all these please send link ask thanks

comment [10]

Hi, What is the parts number for T1B/T2B? Can I used 16F628A instead of 16F88?

comment [9]

Autor projekta je poslao novi HEX fajl sa ispravljenom greskom koji je upravo uploadovan na server.
IP: n/a

comment [8]

Dobar dan.Napravio sam vas projekt PAMETNI TESTER I PUNJAČ BATERIJA i imao bih par pitanja. Punjac radi super---veoma sam zadovoljan(napravio sam ih 2) ali kad sam proverio ampermetrom realnu (potrosenu ili dodanu) struju na izlazu na bateriju nesto mi se bas i neslaze sa tim sto pise na displeju.Neke vrednosti su dobre a neke lose pa bi me zanimalo gde je greska. IZMERENA STRUJA celija punjenje mA praznjenje mA mereno ext.ampermetrom mA 3NI-MH 225

comment [7]

I just wanna be able to print out 8 on a sheet. I use blue press and peel and it's kinda expensive. there is always a change that they won't transfer tot he board properly, so I'd like to have a sheet of them just in case. The creator didn't resize the board, and I can only get 3 circuits on one sheet. It you wanna try to send me the program send it to my name @ gmail [dot] com. It would me much appreciated! :)

comment [6]

This is board for development purposes, but functionality. You don't need to buy program, I will send .exe to you..?
IP: n/a

comment [5]

Anyway anyone can shrink the board down? I can only print 3 on a single sheet, and I hate to waste blue press and peel. I don't wanna buy the program for a simple resize, that would be a waste of money. The circuit is a good size, but the board was never resized. I was able to do it in the demo version of sprint-layout but it won't let me print since it's a demo. I was able to easily get 8 copies one sheet.

comment [4]

How about a parts list to make building this easier?

comment [3]

i contacted the author and he tested some unknown Chinese 900mAh Alkaline batteries. they had only 470mAh capacity :) Nokia’s rechargeable original batteries actually had more capacity then they read on the package! cool
IP: n/a

comment [2]

would you share your source code as well?

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