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I have been recently playing around with several Arduino sketches that have to do with the monitoring of charging and health of new Li-ion cells.
If you happen to live in a part of the world that is unable to access professional level smart chargers then this project might be for you!
The following sketches are quite useful in creating your own battery health monitor.
It should be noted however that you need to externally power your arduino with a wall wart to get this to be at all accurate. I also suggest a proper DMM such as a fluke, Hioki or other high accuracy dmm. (makes it possible to test the ref voltage on the board with accuracy)
Arduinos suffer from a voltage sag when powered from a USB connector and this throws out the ref. voltage.
This could be extremely hazardous when making a charger circuit. Use these sketches with caution.
---> How the battery tester circuit works. When simply testing the mAh of a given battery the battery's positive and negative terminals are given a known
resistive load directly across them. Vbat/Ohm = mA. This is then monitored over 7200Seconds to give mAh rating.
The data is collected via the Arduino terminal.
Also, these sketches do not only give the mAh of a given battery but are also able to calculate the internal resistance at the same time. This is extremely useful for monitoring a battery's longevity/health. High internal resistance = poor performance.
The most basic sketch applies the formula Vbat-Vload div value of the resistor
= internal resistance in mOhms to find the internal resistance of a given cell.
see link below...
How to Measure Internal Resistance ? Battery University
Links to the various arduino projects are below. I can verify that this project does work as intended. You do however need to be careful NOT to over discharge your batteries. I've have personally seen a few of these cylindrical cells become hot and rupture explosively from mishandling them.
Please, please , please .... observe all safety precautions when using and charging Li-ion cells and Li-poly cells.
This is especially problematic if you are using non-protected cells. To get around this problem you'll need to add a Solid state relay to your sketch to cut the discharge off at 3.2v.
Again, these sketches and projects require a little tweaking but the proof of concept is there. I can verify these both work as they're intended to.
Enjoy.
Arduino True Battery Capacity Tester (Li-Ion/NiMH/NiCD/Pb)
Very simple Arduino Lithium-ion battery capacity tester/discharge monitor | electronicsblog.net
If you happen to live in a part of the world that is unable to access professional level smart chargers then this project might be for you!
The following sketches are quite useful in creating your own battery health monitor.
It should be noted however that you need to externally power your arduino with a wall wart to get this to be at all accurate. I also suggest a proper DMM such as a fluke, Hioki or other high accuracy dmm. (makes it possible to test the ref voltage on the board with accuracy)
Arduinos suffer from a voltage sag when powered from a USB connector and this throws out the ref. voltage.
This could be extremely hazardous when making a charger circuit. Use these sketches with caution.
---> How the battery tester circuit works. When simply testing the mAh of a given battery the battery's positive and negative terminals are given a known
resistive load directly across them. Vbat/Ohm = mA. This is then monitored over 7200Seconds to give mAh rating.
The data is collected via the Arduino terminal.
Also, these sketches do not only give the mAh of a given battery but are also able to calculate the internal resistance at the same time. This is extremely useful for monitoring a battery's longevity/health. High internal resistance = poor performance.
The most basic sketch applies the formula Vbat-Vload div value of the resistor
= internal resistance in mOhms to find the internal resistance of a given cell.
see link below...
How to Measure Internal Resistance ? Battery University
Links to the various arduino projects are below. I can verify that this project does work as intended. You do however need to be careful NOT to over discharge your batteries. I've have personally seen a few of these cylindrical cells become hot and rupture explosively from mishandling them.
Please, please , please .... observe all safety precautions when using and charging Li-ion cells and Li-poly cells.
This is especially problematic if you are using non-protected cells. To get around this problem you'll need to add a Solid state relay to your sketch to cut the discharge off at 3.2v.
Again, these sketches and projects require a little tweaking but the proof of concept is there. I can verify these both work as they're intended to.
Enjoy.
Arduino True Battery Capacity Tester (Li-Ion/NiMH/NiCD/Pb)
Very simple Arduino Lithium-ion battery capacity tester/discharge monitor | electronicsblog.net
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