Battery-powered tools have come a long way in the last decade. Moving to lithium-ion as an energy storage medium, instead of the older nickel-cadmium batteries, improves performance and runtimes. It does so to a point that “cutting the cord” has become a viable option for many professional applications. Pros can now do away with lugging around extension cords and generators to the job site. But how long do Lithium-ion batteries last?
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Framing the Lithium-ion Longevity Question
However, because Li-ion batteries are expensive, the move to cordless convenience can prove to be an investment. Naturally, before jumping into a cordless tool line, the discerning Pro will consider how big an investment cordlessness requires in the long term. How long can a battery sit unused? How many charging cycles can you expect from a battery? What’s different about Li-ion batteries? In short, how long do lithium-ion batteries last, really?
We talked to product managers and executives at Bosch, DeWalt, Metabo HPT (formerly Hitachi), Makita, Milwaukee, and Ridgid to get some answers straight from the manufacturers. While the answers vary here and there, there’s a general consensus on the major points.
How Long Do Lithium-ion Batteries Last in Storage?
We wanted to start with battery storage. How long they last when used is one thing—but what about batteries sitting on shelves? After all, that might affect whether or not you want to pick up that “used” pack at the flea market.
A number of external factors affect a battery pack’s lifespan on the shelf. What was the state of the pack’s charge when it was stored? Will the user store the battery in hotter or colder temperatures? Will it be stored on the tool, on the shelf, or on the charger? Who made the internal electronics, and how well do those electronics control the current within the pack?
Of course, if a battery pack drops below a certain charge capacity, the pack will cease charging at all. That signals the end of its usable life, though it’s possible to “resurrect” some dead batteries. The time it takes for this to occur depends, again, on manufacturing processes and components as well as those external factors.
All of that having been said, there seems to be a consensus regarding the average battery pack shelf life. If you take care to store your batteries correctly, you can expect your batteries to last anywhere between 3–6 years on a shelf. The biggest takeaway? Keep your batteries out of the heat. Extreme heat is the biggest enemy to the overall lifespan of Li-ion batteries.
How Many Charging Cycles Can You Expect to Get?
Again, the answer to this question largely depends on a number of variables. Battery configuration and capacity play a part, as do ambient storage temperatures.
User behavior also affects how many charging cycles a battery can go through before it craps out. Believe it or not, you really shouldn’t use your battery packs in place of a hammer. Blunt force trauma will adversely affect the lifespan of your Li-ion batteries.
So, in terms of charging cycles, how long do Lithium-ion batteries last? Despite the aforementioned variables, most of our manufactures claim that users should expect to get over 1,000 charge cycles out of any given battery.
What Exactly is a Charging Cycle?
Now, some of that depends on how a manufacturer defines what a charging cycle is. Typically, one charging cycle equals running a battery down and charging it up again. However, most batteries count one full charging cycle every time you throw your battery on the charger. That occurs regardless of how much charge the battery actually needed.
Makita tells us that they use a “smart” system that accounts for this. Their chargers and batteries use a communication system that recognizes a battery’s current charge level and temperature. Then, the charger regulates the optimal current, voltage, and temperature to recharge the battery. This process extends the life of the battery. It also extends the amount of charging cycles the battery can go through. That’s just one example of why you should stick with the manufacturer’s original batteries and chargers.
As far as how many charging cycles to expect, most manufacturers seem to fall into the 1000 to 2000 charge cycles camp. That’s like charging your battery every day for between 3 to 6 years. We’d recommend living under expectations leaning towards the shorter side of that equation.
How Long Do Lithium-ion Batteries Last Compared to NiCad Batteries?
We know, NiCad batteries have been long gone for over a decade now. Still, it serves as a sort of baseline in some people’s thinking. Because Li-ion has a superior energy density, a comparable NiCad battery will be larger and heavier. From a functional standpoint, Li-ion also doesn’t experience voltage drops as it depletes. So what about shelf life?
Both varieties of the battery will self-discharge in storage. However, NiCad self-discharges at a rate of about 1–3% per day. Because of this, it wasn’t uncommon for an unused NiCad battery to require a recharge every couple of weeks or so—even if you never used it!
Li-ion batteries self-discharge much more slowly. Almost imperceptibly, in fact. The rate at which this discharge occurs largely revolves around the quality of the pack design.
Li-ion batteries also have a lot more technology at work than NiCad batteries ever did. Really, the comparison seems a little unfair and dated. Many manufacturers employ overload, over-discharge, and overheating protection for their Li-ion batteries. All of these technologies protect the battery. They also extend the expected life cycle. NiCad and NiMH batteries typically didn’t have these protections in place.
So, while some may claim that NiCad batteries were also expected to last through 1000 charging cycles—you had to charge those packs many more times during their use. You also had to deal with the dreaded “battery memory effect”. OK, that’s the last time we’ll talk about old technology—we promise!
The Bottom Line
So, how long do Lithium-ion batteries last? To sum it all up, the bare minimum that most manufacturers expect from their batteries is around 3 years or 1,000 charging cycles (whichever is less). With that said—we say “put your warranty where your mouth is”. Bosch, DeWalt, Metabo HPT (Hitachi), Makita, Milwaukee Tool, and Ridgid all warranty their Lithium-ion batteries for 2–3 years. That’s a real good indicator of their minimum expectations for those packs.
If you take care of your batteries, there’s no reason not to expect them to last at least that long or longer.