How to dispose Lipo Battery | Old or Damaged Lipo

by Oscar
Published: Last Updated on

The inevitable question for RC hobbyists is how to get rid of old and damaged LiPo. LiPo batteries can extremely dangerous if not handled correctly, causing fire and even explosions. In this guide we will show you how to dispose LiPo batteries safely.

This article explains how to determine whether a LiPo battery is old enough to retire.

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 over time. 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.

  1. Get a plastic container which you can afford to throw away, fill it with cold water
  2. 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
  3. 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
  4. 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.

lipo-discharge-twist-positive-negative-cable

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.

Checking Voltage

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

Edit History

  • Oct 2014 – Article created
  • Jul 2016 – Updated
  • Jul 2018 – Updated “Other discharging methods”

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14 comments

Keith Miles 29th January 2020 - 7:23 pm

It should be more clearly pointed out that, whilst less convenient, a low discharge current is always preferable to ensure maximum safety. The higher the discharge current the greater the convenience but the greater the need for monitoring of the discharge and the battery condition.

Also, it is not practically possible to have a simple single discharge device to suit a wide variation of pack cell counts and capacities for a given discharge rate (e.g. 0.1C) and discharge time (e.g. 10-12 hours).

2S 600mah @ 0.1C discharge current would require a resistor/load of value 123 ohms/0.4 watts.
3S 2000mah @ 0.1C discharge current would require a resistor/load of value 55.5 ohms/2.22 watts.
4S 5000 mah @ 0.1C discharge current would require a resistor/load of value 29.6 ohms/7.4 watts.

On balance, my preference would be a slow discharge (0.1C or less) in a bucket of sand placed in a suitably safe location! Why rush?

Reply
David Dobbs 7th November 2019 - 4:42 pm

I use 3 cell packs that are “low” for my motor starters (large packs) and electrical drills (small packs that fit in battery case, ex 1300mah w/access to leads). Also in portable compressors w large packs.

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Strepto 29th March 2019 - 11:41 pm

This video will teach you everything you need to know: youtube.com/watch?v=49maaWRQOog

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Oscar 1st April 2019 - 1:21 pm

Fun video lol :D

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Roger roger 5th January 2019 - 10:02 pm

Point to add, if you agree, then short the main wires after fully discharging so that no charge can build up again.

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Oscar 10th January 2019 - 3:11 pm

Emh… I think I did mention that. But thank you anyway for emphasizing that :)

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famtory 8th October 2018 - 2:48 pm

Electrolysis of salt water produces chlorine gas. It is a very deadly gas.

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Sally W 13th July 2018 - 2:02 pm

You can hand them in at the used battery collection point at the hardware store, but in reality a full depleted LiPo battery contains only lithium salt(s), cobalt/manganese/graphite, water and plastics, neither of which are considered toxic chemicals and can be handled by the normal waste processing plants.

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John Richardson 8th September 2017 - 5:18 pm

A light bulb is a resistive load and a motor is an inductive load

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James Stonehouse 22nd February 2020 - 5:32 am

From the perspective of draining a battery, the battery doesn’t particularly care whether the load is resistive or inductive, so long as the current draw isn’t so high that it goes into thermal runaway.

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Iain sp7 6th January 2017 - 11:55 pm

There are many good other uses for old Lipo batteries , such as running all sorts of appliances esp if they are still holding correct volts but not giving good amps, i do music and use them for my effects boards and led light circuits, use for handsets & goggles, maybe good for pedal bike lights, head torches etc, if anyone is doing FPV racing n making their own hoops n markers , why not light them up for night time fun using EL wire ( ebay.co.uk/itm/271866563089?_trksid=p2060353.m1438.l2649&var=570702685340&ssPageName=STRK%3AMEBIDX%3AIT ) and old lipo batteries to power them up :)

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Ben Portman3 13th July 2016 - 12:49 am

Any shop that sells batteries should recycle the batteries they sell, so for lipos….that’s everywhere, just take them to a shop and ask them to get rid. do it before we (if) brexit.

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Eric 5th July 2016 - 12:43 am

I check the LiPo for dead cells first. If cell 1 or cell 4 are dead I remove the faulty cell and then have a test 3S for
flight tests.

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The almighty 31st December 2015 - 11:36 am

salt water corrodes and eats away at the tabs that connect the wire to the cell, so when you measure voltage from the connector you get a 0 Volt reading because its now an open circuit. the cell still has energy in it.

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