Im a student and im currently an intern at a company, which asked me to make a charger for Polymer Li-ion Batteries. They only use one type of battery and that is the LP401730 150mAh. The reason I want this to be with Arduino is because the batteries can't be charged all the way, sinds the storage cappacity of batteries is between the 45% and the 55%. So meaning it can't just charge from 3.7V to 4.2V, but needs to stop at 3.9V wich is about 50- 60%. This is not hard but there needs to be multiple batteries at a time, and i want to monitor them sepperatly. Do you guys have any idea how i could pull this off?
I was thinking about using the charger breakout board based on TP4056 in combination with arduino.
the problems I run into are:
I have never worked with Arduino and there isn't a lot on the web (I know, I should be ashamed)
there needs to be about 9 batteries charged at a time
I want to monitor the batteries seperatly like: battery1 = ...% battery2 = ...% ect.
it needs to be portable, so not connected to the PC all the time.
Time, they gave me the project a bit late and my internship is almost over, would like to finish this project sinds i like the idea of it.
the batteries come with a 3-way molex connector, and only use 2 of them (vcc, gnd)
The Arduino MEGA has 16 Analog inputs you can use to measure the battery voltages. INFO HERE
What current do you want to charge at?? C is 150 mA what is that battery rated at for "fast charge" ??
What If:
You get / make a regulated power supply set at 4.1 volts (So you can not overcharge)
You set up each battery connector with a series resistor of R=E/I = (3.9-3.7/.05 = 4 ohms to charge at 50 mA
You measure each battery voltage. If the voltage is less than 3.9V you light a LED next to that battery to show it's charging. If the voltage is 3.9V or above you flash the LED (The battery is charged, or no battery is connected)
Write the voltage measurements to the Serial Monitor (but system with LEDS will run standalone).
Thank you Terry for the link to where I can learn more about Arduino, really needed that . The Arduino MEGA looks really interesting too. I will look more in to it.
The TP4056 is a fairly low cost LiPo Charger, about 20p as I recall.
If you used one of these for each individual LiPo, the charger IC will deal with any issues relating to low battery voltage for you. The TP4056 will, if you leave it alone, safely charge the battery up to the normal full voltage.
You dont want full voltage so use an Arduino to monitor the battery voltage and turn off the charger via its CE pin when it reaches 3.9v or so.
You need a fair bit of I\O for this setup, an Arduino Mega would be ideal.
The advantage of this approach is that all the safety issues relating to charging are handled by a chip designed for just that, the TP4056.
So whatever your code or hardware does, it cannot cause a safety issue, if you wire the TP4056 correctly. The worse that should happen is that your program will not detect partial charge properly and the cells end up at normal full charge, the charge complete pin on the TP4056 will even tell you this has happened.
Thank you srnet for helping me. I do have to tamper with the tp4056 module, by changing the resistor. its made for 500mAh and will change the resistor to 10k so that i will get about 130mAh. I read it was always saver to never go above 1C. But I dont think that would cause any problems. I think I will try this out.
. The Arduino MEGA looks really interesting too. I will look more in to it.