Lithium Ion Batteries and Fires

By Jon Eakes

The media has been playing up the recent recall of Lithium Ion batteries by both Dell Computers and Sony, creating a lot of worry about this technology as we have more and more power tools that are using Lithium Ion technology.

What is the problem?
There have been a number of incidents of spontaneous fires breaking out ever since the creation of Lithium Ion batteries a dozen years ago. At first, the fires were in large shipping cases full of batteries, then occasionally in modern electronic equipment such as computers and cell phones. Basically when certain configurations were struck, causing a shock inside the battery, they would go into a self-feeding chemical reaction that would self-destruct.
What is important to understand is that Lithium Ion is a category of technology with a wide range of formulations. Most of those early problematic formulations no longer exist. In addition, batteries in electronic equipment are small, packed into tight containers and close to hot circuit elements with little or no thermal overload protection.
Lithium Ion technology for power tools is quite different. Rather than drawing less than one amp, power tools draw five to 40 amps - hence, thermal safety devices were built-in from the beginning. Hitachi, to its credit, is the only tool company to put out a press release about this problem, basically pointing out that their power tool batteries have a number of safety features specifically designed to protect the batteries both during charging and during use. Phone calls to all the other manufacturers producing Lithium Ion power tools all gave variations along the same lines: This is a different technology with many safety features built in.
So, although you may need to worry about your cordless computer, you don't have to worry about your cordless power tools. HB