The inevitable question for RC hobbyists is how to get rid of old or damaged LiPo (Lithium polymer battery). There are tons of videos online showing how dangerous LiPo batteries can be if not handled correctly, causing explosions and fire. In this guide we will show you how to dispose damaged and old LiPo batteries safely.
LiPo Disposal Summary
When disposing LiPo battery, the goal is to discharge them completely until there is no charge left (0 volt). So that they won’t burst into flames when punctured. Finally bring the discharged battery to your local battery recycling facility.
# LiPo Charger
Your LiPo charger might be capable of discharging your battery. If you do so, remember to discharge it at a small current for safety, e.g. at 1/10 C, for example, for a 2000mAh 50C pack, discharge at 0.2A (2000/10=200mA).
However most LiPo chargers have a cut-off voltage of 3V, it won’t discharge your battery further once it reaches 3V per cell. Because chargers are designed to work with batteries only at their safe voltage range. If this is the case, you might want to consider the other methods in this guide instead.
# Light Bulb
Light bulb is a popular option for discharging LiPo batteries, because it’s fast and cheap.
In this tutorial I will show you how to built a Halogen Bulb Discharger.
Try to avoid LED type of light bulb, as they have “forward voltage” which means when voltage drops below a certain level, it will simply stop discharging leaving a small amount of charge. Also LED are more energy efficient which means it will take longer to discharge. It’s best to use Halogen bulbs.
You can also use some kind of resistive load instead of light bulb, for example a radial ceramic resistor. For example, for 2S or 3S Lipo, you can also use 150ohm 2W resistors.
# Other Effective Methods
I covered many good ways to discharge your batteries ready for disposal in this article, including dedicated battery discharger, and high power resistors.
# Salt Water
This is not the most recommended method, because it’s slow and ineffective.
Salty water is conductive and it discharges the battery slowly overtime. It’s also said that salt causes chemistry reaction with the substances in the LiPo battery, and neutralizes the Lithium. However I am not a chemist, so I hope someone can verify this theory.
However the problem is that salt water might not completely discharge your lipo. Corrosion can take place, where the exposed metal of the connectors/wires will have a layer of insulator building up in salt water. Eventually the electrical conductivity would slow down, even stop the discharging entirely.
The advantage is that your battery is relatively safer to discharge as it’s immersed in water.
- Get a plastic container which you can afford to throw away, fill it with cold water
- Mix it with salt and make sure it’s dissolved completely. I always use about 30g of salt per litre of water and that has been giving me good result
- Put the battery in the salty water, and leave it somewhere fire proof for two weeks. Depending how much charge it had originally, you might want to leave it longer
- Finally, wrap the battery with paper and it’s ready to be thrown away
# Physical Destroy Method
This is the least recommended method because it’s dangerous. Actually, I don’t recommend it at all. We’ve seen people use a gun to shoot through the battery, use a nail to puncture it, or use hammer or brick to break it and let it ‘explode’. This is probably the quickest method, but fire hazardous and the smoke is not good to breath in.
How do I do it?
Personally, I prefer to use a halogen light bulbs discharger to completely discharge the pack first, then I cut the connectors and twist the discharge leads together to ensure there is no energy left in the pack (+ and -). This way it normally only take less than an hour which is far more efficient than dipping the battery in salt water for weeks.
It’s useful to save the connectors especially the balance lead, if you have one damaged on a good pack you can use it for replacement.
A few tips on using Lipo
- Always charge LiPo battery supervised
- Always use the balance charging (balance plug)
- Always use a lipo-safe bag if you have one
- Always dispose LiPo batteries properly.
- NEVER short a LiPo battery.
- NEVER try to use damaged or puffed up LiPo batteries.
- NEVER over-discharge a lipo, it will reduce the life span, and might cause safety issue.
Follow these methods at your own risk, and do everything necessary to prevent fire. Consult a professional if you are in doubt. Keep away from human and animal when you are doing any of the above.
Before throwing the battery out, you want to check there is no charge left in it (voltage is close to 0V).
Note that most battery checkers don’t work well when voltage drops below 3V per cell, and will report “no cell present”. Therefore it’s best to use a multimeter in this case.
- If you don’t already have one, here are some cheap and basic options: Banggood | Amazon
- But I recommend investing a bit more to get a more advanced one like this: http://amzn.to/2xIaV9Z
- Oct 2014 – Article created
- Jul 2016 – Updated
- Jul 2018 – Updated “Other discharging methods”