While balancing or just in general use, I sometimes want to lower the voltage on a particular cell in my battery bank quickly and safely.
After trying numerous methods, I found this approach to be quick and easy and it does not require any special equipment or tools.
I used the household extension lead in the picture below with a brand new 280ah LifePO4 cell.
I used an old 14 gauge 50ft cord with a simple loopback (yellow wire in the picture) effectively making the wire 100ft long.
You could use any long extension lead, of smaller or larger gauge. Just check the resistance is between 1-10 ohms. Any cheap multimeter can be used to check resistance.
I connected to the lead Live/Neg prongs with alligator clips using some existing cables from my garage.
You could connect the wires many different ways, just ensure the connections are solid.
The total wire resistance when tested, measured 2 ohms, 1 - 10 ohms is the sweetspot.
There were no sparks, nothing eventful connecting the wires. No wires got hot, not even slightly warm. You do not need to uncoil the lead as the EMF effect is cancelled out by utilizing the reverse wire.
Remember - You are not using 120v or 240v AC, but 3.2v DC. Very different! Do the math.
It's not the same as putting a screwdriver across the battery terminals. If you don't understand the physics, please don't post untested contraversial shock theories.
I checked the voltage every minute with a multimeter. The voltage
dropped from 3.6v to 3.3v in 15 minutes
All in all, a success. I would recommend this method over any other, as it's safe, fast and practical.