High-power Lipo Discharger

 

I decided to build a Lipo discharger this week. Most off the shelf products were expensive and underwhelming for my needs. I am attempting to discharge a 6s 16ah 24v Lithium Polymer battery which has recently had cell issues after 6 years of regular use. Instead of throwing it away carelessly I wanted to empty the battery of all power therefore making it inert.

 

I have seen some homemade battery dischargers on the internet which use 50w 12v car light bulbs in an array to increase the amps pulled from the battery thus emptying it more quickly. It should light up your space like a lighthouse. These bulbs can be bought for approximately £4 each.

Other options I have considered are Industrial Resistors which are often used in home wind generator setups to help dump the load when the wind is too high and the power generated too great. The power has to go elsewhere so a large capacity resistor can do. Typically a 24v 300w resistor costs around £25.

Another interesting option I thought about was my final idea. I found via the internet that there are super cheap 12v/24v immersion heaters for car vehicle 12v sockets. They are used to heat a cup of water in your vehicle so you can have hot tea or coffee. After a few rudimentary tests I found the immersion heater to draw 220 watts of power without melting the cable or plastic. I found them for sale at £4 each. 

 

So I decided to buy 4 of these DC water heaters:

4 x 220 watts = 880watts of discharge power

 

The commercial 200 watt lipo discharger is around £70, so we can discharge 4 times higher than this.

I wired the heaters up so that i could have two or four connected to allow variable discharge rates.

I also included an emergency stop button in the event I need to stop the discharging cycle for some reason.

When it is time to discharge the lipo I place the immersion heaters into a glass bowl of water and let them heat the water, it is a plus if boiling point for tea is achieved.

Thanks for reading.