Why Cordless Battery Tools Fail so Much

Cordless drill


VladK213 / Getty Images

Lithium-ion battery cells make many cordless tools possible: drills, reciprocating saws, circular saws, impact drivers. These batteries are getting so good, even nailers and lawn mowers are being powered by lithium-ion batteries.

The dark side is that these batteries are notorious for their high failure rates. And surprisingly enough, unlike ni-cad batteries, which fail in slow stages, lithium-ion batteries fail all at once. One minute they're working, the next minute they're not. You cannot revive them in any way. Disposal is the only answer.

Why does this happen and how can you prevent battery failure?


At this stage, development still has a ways to go before lithium-ion batteries will overtake the world of tools. None of the batteries in cordless tools will last more than a couple of years. Tools powered by ni-cad (nickel cadmium) batteries, though heavy and low-powered, are still going.

Is that acceptable? Let's say that two years is an acceptable lifespan for lithium-ion batteries. What is unacceptable is when they fail far prior to that two-year term—and so suddenly.

Everyone has had cordless tools work one day, fail the next. Unlike ni-cad, lithium-ion batteries fail all at once, not slowly. Many of these have been rather new lithium-ion batteries, too.

As it turns out, lithium-ion batteries are like temperamental rock stars: they are overly sensitive and must be treated gingerly. If they go outside of their comfort zone, they refuse to play.

Thermal Runaway

In short, lithium-ion batteries have failure built into their design—as a safety precaution.

Lithium-ion batteries, if they get too hot, can cause fires. The chance of this happening is extremely low. But stories of batteries catching on fire are so dramatic that they give the impression that lithium-ion batteries are catching fire all the time.

The fancy term is thermal runaway. When a lithium-ion battery strays outside its internal electrolyte low range of 158 to 194 degrees F, runaway occurs. The higher the juice in the battery, the faster the runaway. Runaway temps can soar to a blistering 1,110 degrees F.

These top-range temps can cause the battery to pressurize, pop, vent gasses, ignite gasses, and spew battery cell contents. That's when fires happen.

Battery Management System

Before that, hopefully, the battery's internal management system (BMS) has kicked in. The BMS is like a fuse. Fuses in the house or car are designed to fail in the event of high floods of voltage.

It's not an act of charity that has compelled manufacturers such as Ridgid to offer free lifetime battery replacement programs. It's Ridgid's way of addressing the gap between the hunger for lithium-ion battery-powered tools and the current state of such fuel cells.