I really knew nothing about electronics or circuit boards a few years ago before I had this hobby. Because I had to deal with so many issues, fixing controllers, electrical issues, building my own battery pack, etc., I've became a lot more knowledgeable about electronics. I practically knew nothing before this hobby., Of course thanks to all the people on this board who helped me learn along the way.
I am proud to say that I actually hacked a lithium ion protection board to control the cut off voltage for my heated electric clothing.
The issue was that I had made my own 18650 12 volt packs for my heated clothing but the PCB (Protection circuitry board) would cut off at 2.7 volts, which was way too low for my use. I wanted a 3.3 cut off voltage. All PCB boards you can buy all shut off at 2.5 volts or 2.7 volts, and we know that is way too low. So I had to constantly monitor the voltage, use cell alarms to warn me when I was around 3.3 volts, but I just wanted the battery to cut off at 3.3 volts.
I searched google to see if anyone had a solution, and some people asked about it, and even put some ideas forward to make their own cut off board, but nobody has actually found a working solution that I could find.
So with my knowledge from my ebike hobby, I figured I could figure out a solution. If I could fake the voltage into the microprocessor a cheap china PCB could be hacked and controlled. This was done with using a 100k pot as a voltage divider to adjust the voltage to exactly what I want. Of course I got some tips on the way, like using a voltage divider instead of just a resistor.
While some of you will think this is easy, and many of you on this board are worlds above me when it comes to electronics, I'm happy to know that I actually was able to hack this board to control the voltage. I also had to figure out how to do on my own as nobody has actually done it or even the idea about hacking an existing board.
Some pics of the board and pack. The only issue is the PCB cuts voltage off at 2.7 volts and needs to rise above 3.00 volts to turn the pack back on. When a Lithium ion battery is empty it will easily bounce from 2.7 to above 3.00 volts after the load is removed but not when the voltage is actually 3.3 volts and would need to go to 3.6 volts. So I had to have a separate charge connector to charge the pack above the faked 3.00 volts, or charge it above 3.6 real voltage.
Battery is on charger before I wrapped the pack in tape.
Battery wrapped in tape and ready to be used. Could you imagine bring this through airport security.