Page 8 - Demo

DISPOSAL OF LIPO BATTERIES7Just about every one of us in this hobby is using Lithium Polymer batteries, commonly referred to as LiPos. Most of us probably have a range of them, in various series configurations and capacities. The stories abound of the dangers of these batteries, how incorrect charging and disposal has created catastrophic and deadly fires, and the bigger the pack, the greater the risk.All of us who use these batteries therefore have %u201cdead%u201d packs, ones where one cell or more has stopped performing, probably on the shelf somewhere. This article seeks to explore the means of disposal of these batteries. Incorrect charging and fires arising from it are not going to be discussed in this article. PreparationThere are innumerable videos on Youtube showing the discharge of lithium batteries, many of which display some pretty dubious %u2018scientific%u2019 techniques for rendering packs safe by fully discharging them. Here are three that are worth a watch.This first one is a series of experiments, not particularly scientific, on the reaction in a cell, and between cells and packs when a fire occurs. It also demonstrates the efficacy of Battery Bags. The use of fireproof containers, especially bags, is always recommended.https://www.youtube.com/watch?v=4Ajz9t3CYbcNote in this example the apparently soft reaction to damaging a cell by puncturing it, not the explosive reaction we have come to expect. Fire resulting from a Lipo failure, on DISCHARGE is mostly about the pack%u2019s immediate environment; what is around it that is combustible and is there a supply of oxygen?Many people believe and expound that a salt water bath is the only way to fully discharge a Lipo. Based on my experience in electronics I had some reservations about this method being the only safe process. In this next video, the Blogger discharges the pack using a saltwater bath and then checks cell voltages, the results show very tiny voltages.https://www.youtube.com/watch?v=YD--N__dpIkInterestingly, he %u201cforgets%u201d to halt the test for a month, the results are the water bath has gone dry, but the pack has had plenty of time to die. His final test is to puncture the pack, and gets no reaction, ie the pack is out coldThis next video compares discharging a battery with the saltwater technique versus an electrical load.https://www.youtube.com/watch?v=E0dBCeOPw4cThe test he shows results in a fully discharged pack, down to minimal volts per cell and it still gives a minor reaction to the puncture test. Interestingly he has run the bath for only three days. What I think is significant in this method is the excretion of possibly nasty chemicals and fumes, and the possible erroneous result arising from corrosion within the pack..This Blogger%u2019s alternative method is to use a dummy electrical load, for similar time. The pack is fully dead with no reaction to being punctured. To be sure it is saqfe, hew twists output wire together which will short out any voltage left.For what it%u2019s worth, I use something like this latter method, but cheaper, easier and as effective. I have made up a load using a 12v car lamp (mine is a turn or tail lamp, 12W) on to the mate of whatever connector the pack has, this one just happens to have a Deans on it. This ok for 3S packs; you would need to wire two bulbs in series for packs of 4S or more.Then I purposely forget it and it may stay connected for weeks until I may need to discharge another one, neither the current draw or the time is critical, the longer the better. This 3S 2200mAh pack started out %u201cflat%u201d at 7.6V and the lamp continued to glow for nearly 3 hours, current drain I guess at something less than 0.5 Amp. After one hour the p a c k , w h e n disconnected was down to 6-volts and Two lamp bases wired in seriesTo connectorNegative Positiveto 0-volts the next morning. Maurice Jobs