Early generation battery-powered tools relied on nickel-cadmium (NiCad or Nicd) or nickel metal hydride (NIMH) batteries. Because of the relatively low power density of these batteries and the fact each cell put out about 1.2V, space and shape limitations meant they were configured in low voltages (e.g., 4.8V or 9.6V).
This meant they didn’t have enough “oomph” for a drill motor to produce the kind of torque needed for the typical industrial user. And they didn’t last long enough between charges to make them practical for much work on a job site. Most of today’s battery-powered tools were not possible back then due to this limitation.
Then something started happening. Batteries made with lithium-ion (Li-ion) or lithium polymer (Li-poly) technology began replacing the older style batteries in laptop computers. They also made today’s cell phones possible. In use today are half a dozen main kinds of lithium configurations plus some oddball ones. For simplicity’s sake, let’s call these and any other variations of lithium-based batteries “lithium batteries.”
The advent of lithium batteries for power tools was a game changer. These batteries can be made without a liquid electrolyte, so any desired shape and size that fits a tool is possible. More importantly, the cells can be arranged into batteries with much higher voltages. For hand-held power tools, 20V seems to be standard today, and it’s more than adequate.
Now you can buy a drill with a lithium battery and get all the torque you need along with long runtimes between charges. And the tool choices go way beyond just drills.
You could say there’s been an explosion of products in the lithium battery tool market. And the “explosion” part has a double meaning. One meaning is far more choices. The other is safety requires new practices unique to the charging, storage, and use of lithium batteries — and the use/storage of the tools they power.
Lithium battery charging basics
You may have noticed that lithium battery chargers for different tool families are not interchangeable. It used to be that each tool was designed with a battery and charger specific to that tool. This created a mess of incompatible chargers on a typical job site where battery-powered tools were in heavy use. Even consumers were not happy about having six different chargers in their garages.
Manufacturers responded with tool lines or families using the same battery and charger. Regardless of which tool it is, you just slide the depleted battery out, put it on a charger, and grab a fresh battery. You also eliminate the clutter of half a dozen batter chargers with half a dozen cords running to outlets.
This works great if you built your tool collection on this tool family battery concept — not so great if you didn’t.
Battery chargers are easily damaged when subjected to an excessive force (for example, being dropped onto a cement floor). A common failure mode is excess charging voltage due to damage to the voltage regulator. Your batteries may appear to be charging, when, in fact, they are not.
Best practice: Keep a battery charger in a protective case (such cases are often provided with the tool/charger set) when not in use. On the job site, set up a charging station that is protected from foot traffic, arc welding sparks, metal grinding dust, heat sources, spilled coffee, and the weather. Ensure the chargers can be used easily but are situated in such a way that they won’t fall off whatever you have them sitting on. Also, remember that many chargers are fan-cooled for a reason.
To avoid overcharging, assign someone to check the chargers at each break. If the green “charged” light is on, remove the charged battery, and put it wherever you keep the charged batteries. Unplug any charger that is not in use. It’s also good to periodically wipe the battery contacts and their mates in the charger(s) with a clean, lint-free cloth. Common eyeglass cloths work for this purpose.
Lithium battery storage basics
Shorting across the battery terminals can cause a significant arc that vaporizes metal, sending particles straight into your skin or even your eyes. If you use the manufacturer’s battery caddy or similar fixture, you eliminate any chance this will happen.
Ensure nothing is set or thrown on stored batteries by choosing a location and storage method that prevents both. Obviously, the main hold of a gang box is not a suitable location. You can buy a stand-alone battery box to place in the gang box or a gang box with built-in battery charging features.
The storage location needs to be out of direct sunlight and away from heat sources. A standard metal cabinet can be modified to be a charging cabinet, but with all the battery storage and charging station products to choose from today, simply purchasing what you need is easier and will probably cost less. Such products exist for use not only in the shop but also in the field.
Make sure you store batteries away from corrosive vapors. Don’t store them near paint, solvents, cleaners, or the like.
Lithium battery usage basics
Always snap the battery securely into the tool, then check it by trying to pull it back off without depressing the release mechanism. Why bother with this check? Because if you start to walk off and the battery falls onto the cement floor or other hard surface, it will likely be damaged even if it appears to be okay (if this does happen, discard the battery and get another one). A battery could also slip off while you are at elevation. In that case, you put more than just the battery at risk.
When your company first receives new batteries, someone should record the serial number and date of purchase. Depending upon usage, these batteries typically last two to four years before needing to be replaced. To make it easy to spot aged batteries, you could put colored dot stickers on each battery, and use a different sticker for each half-year. If you put the sticker on the tool-facing part of the battery, it won’t be rubbed off by force of using the tool. A dollop of paint will also work.
Tips for using battery-powered tools
Paying attention to some simple rules will extend the life of the tool, help protect the battery, and help protect both the people using the tool and other people in the area.
- Don’t set your battery-powered tool on the top (or any other) rung of a ladder. If the ladder has a tool tray or tool caddy, ensure it can securely hold that tool.
- Even if you are using the tool outside in direct sunlight, try to set it down in a shaded area when not using it.
- Never force a tool.
- Check bits or blades before using them. If you plan to do a lot of cutting or drilling with this particular tool, install a new bit or blade before starting the work. This reduces battery strain, motor wear, bearing wear, and the chance of “piece kick,” while it improves the quality of the work. You can buy a whole set of jigsaw blades for $12, so don’t give up all those benefits for a buck or two.
Always remember that a power tool is a dangerous tool, whether it has a cord or not. A battery doesn’t make it any safer — only you can make using it a safe experience.
You’re in charge
Tools powered by lithium-ion batteries have dramatically changed the way we work. They’ve reduced cord management, improved workforce mobility, and spurred the development of new tools that solve old problems.
But they are not without their own problems. Those problems are easily averted if you use some care when handling, storing, or charging batteries — and if you treat all power tools with the respect they deserve.
The battery itself should remind you that when it comes to using these tools safely, you are in charge.
Mark Lamendola is an electrical consultant based in Merriam, Kan. He can be reached at [email protected].
