President's Perspective-2007/04
If you use rechargeable Lithium batteries of any type ... handle them with appropriate care.
Where do you store and charge your Lithium batteries? Have you given much thought to that? Unfortunately, there has been another fire that took an AMA member’s house, but luckily it did not result in any injuries or loss of life. This time the situation concerns me more than past instances. In this case the modeler reportedly had taken the battery off of charge and placed it on the bench while he went into the house for dinner. That is right—the battery was not connected to the charger when it burst into flames and set the wooden bench and surrounding material on fire. The fire consumed the entire house but the modeler and his family were able to get out safely.
This incident, which has not been fully investigated as I am writing this, brings up a new, potential problem and it is one from which we can all learn. Before this episode, I had never heard of a fire started by a battery that had been taken off the charger unless it had been visibly swollen during the charging process or had physical damage. From the report I received, this battery did not show any damage or swelling when it was removed from the charger, so it should have created a minuscule threat for fire. Did the modeler look the battery over carefully? Had it started swelling but it was not apparent? Was it excessively hot? What charger and charging rate were used? Was the pack balanced during the charging process?
We still have many questions at this point, but that does not mean that we should ignore the incident.
I have gotten involved in electric helicopter flying, and in the course of this have had an opportunity to see various methods of handling batteries during charging and storage. I’ve seen the whole spectrum of care being given to these processes. I’ve seen batteries thrown onto paper sacks, lying loose in toolboxes, secured in fireproof vaults, placed in a product called the LipoSack, and charged in a Battery Bunker container.
During transport, charging, and storage, is there a correct way to handle these batteries? No, there is not, but there are “smart” ways and “not-so-smart” ways. Fortunately, fires with Lithium batteries are still somewhat rare, but when they happen, they are serious. The rarity of an occurrence has a tendency to lull us into the habit of using bad practices in handling these batteries. If you use rechargeable Lithium batteries of any type, it is in your best interest to respect the dangers and to handle them with appropriate care.
Personally, I prefer to store and transport them in a fireproof container. I use a LipoSack for this purpose, and I like to charge them in this sack or in a Battery Bunker.
Chargers are another potential source of difficulty. Many of them charge through the two‑wire output plug, ignoring the balance connector (the balancing lead) which is there to monitor the status of each cell in the pack. I would not use a charger without some form of balancer. A large number of the fires that have been reported to me involve chargers that do not have any active balancing component. It does not matter if this feature is part of the charger itself or a separate component that plugs in, but the continued charging of Lithium batteries without a balancing system can lead to trouble.
I’m amazed when I hear from people in person and on Web sites that they are going to buy a balancer when they can afford one, but they keep charging and using the batteries in the meantime. This can be a dangerous game of roulette and it’s putting your property and your family in jeopardy. Please do not do this! Imbalance in the cells in the battery is the most likely cause of swelling in a cell and an ensuing fire.
I’m also astounded when I hear or read about people who are still using batteries that are visibly swollen. I even came across an advertisement on eBay in which the items being sold were Lithium batteries that were “only slightly swollen.” I hope you were not the person who bought them!
Recommended practices (from my experience and reports):
- Store and transport batteries in a fireproof container (LipoSack, Battery Bunker, or similar).
- Charge batteries inside a fireproof container when possible.
- Use a charger with active balancing or use a separate balancer that monitors each cell.
- Do not continue to use or charge visibly swollen batteries.
- Do not delay buying a balancer while continuing to charge unbalanced packs.
Til next month ...
Dave
Dave Brown AMA President [email protected]
Transcribed from original scans by AI. Minor OCR errors may remain.
