It's time to replace the lithium-ion battery, or maybe you just realized that it's handy to have a spare or two. So you load up your pickup truck and head to the local hardware store, where you shop for your beloved cordless tool. When the helpful salesperson takes you to the right replacement tool battery, you start to notice the price tag. $50, $75, even $100 or more! Panic starts to set in, and you wonder if you can find a better deal online.
When you get home, you fire up your old Commodore 64 and wait to connect to the Internet via the modem's piggies. A Google search for "replacement tool batteries" turns up over 16 million sites to choose from. Of course, you are looking for the best price. A battery is a battery, right?
Well, not that much.
First, there are hundreds of variables in the manufacture of the lithium-ion batteries that come with tools. Check out our discussion with Milwaukee Tool's Paul Fry about their RedLithium battery technology. Let's look at the problem with aftermarket and counterfeit replacement tool batteries. Then you can decide for yourself if it's worth the cheap.
Table of contents
- Replacement Power Tool Batteries from Third Party/Counterfeit Manufacturers
- Replacement batteries use a different case design
- Potential below standard batteries
- forget e-newsletters
- Replacement Tool Batteries No True Warranty
- Li-ion batteries are extremely reactive
- Lower overall battery pack performance
- The Bottom Line on Replacing Tool Batteries
Using an aftermarket replacement tool battery presents many potential problems. Here are the most common considerations you should consider before using third-party batteries that cost half the cost of cordless tools.
The design and composition of the battery is kept a secret by the manufacturer. Some third-party manufacturers may try to reverse engineer it, while others just want the tool to do something when you press the trigger. Either way, they're not going to recreate the exact same original design, which causes problems.

Replacement batteries use a different case design
Manufacturers use very specific designs for batteries. It helps dissipate heat, which is the number one killer of Li-ion battery performance. It's also responsible for how the battery drains moisture out of the battery and provides vibration protection.

Potential below standard batteries
Batteries vary widely, and you can find hundreds of different models of battery packs to generate electricity. Manufacturers also use different lithium salts as electrolytes. There are also many options for the type and amount of materials used as cations and anions.

These batteries are not as simple as a set of AA batteries working together. Adjusting any variable in a replacement battery can affect heat generation, power output, run time, and more.
forget e-newsletters
If you haven't read the rest of this article, read about changing tool batteries! ! ! Today's cordless tools rely on communication between the battery, tool and charger. This prevents fatal damage to the tool or battery during charging or discharging. Aftermarket and counterfeit batteries will not communicate with the tool the way they are designed. They bypass all functions designed to protect the tool and battery. After all, this communication is proprietary and closely guarded.
Imagine this scenario: you get a counterfeit battery and it works. Why? Because the easiest way to reduce battery cost is to have the battery send a "go" signal to the tool. In addition to no longer monitoring the motor heat, now your battery can fully power the tool until it melts the windings.
Clint DeBoer, Editor-in-Chief, Pro Tool Reviews
First off, most manufacturers have at least a one-year warranty on their batteries. Some last 2 or 3 years, and Ridgid offers free lifetime replacement tool batteries. Fill out the registration information online and save your receipt. This simple step may alleviate the problem entirely.
If you choose to use a third-party battery, it may not come with a warranty, and your cordless tool warranty will be voided when you lock it into the tool. If your tool fails with an aftermarket battery, they will be able to judge and will not honor the warranty.
Li-ion batteries are extremely reactive
Did you know that lithium is one of the highly reactive elements in the periodic table? Yes, the same chemistry that makes it an essential element of a rechargeable battery also makes it an excellent candidate to fail in pretty spectacular fashion. In fact, if you're willing to sacrifice your battery, you can shoot many models out there and witness a fiery death.
On second thought, don't actually try this at home. Leave it to the professionals. The point is, if you don't pay attention to how your battery is built and protected, it can cause a very serious, literal meltdown. While most batteries use relatively stable lithium-iron-phosphorus ions, poor structure or poor chemistry can make them unsafe for short periods of time.

Lower overall battery pack performance
As I mentioned when talking about batteries, changes in any variable within the battery can affect performance. Run times will be reduced, power and torque will be below manufacturer specifications, and heat will be a major concern. This is due to the use of cheaper materials and the way they are combined in the housing.
In addition to the performance of the tool itself, adjusted size and weight can also affect tool balance and ergonomics.

Let's make this public now. Most batteries are already made in China. Original manufacturer batteries are produced by reputable companies that meet specifications in a manner that produces reliable results. Many counterfeit replacement tool batteries are produced to varying specifications. At best, they are failed attempts at reverse engineering. At worst, they bear little resemblance to the original batteries and are improperly installed.
Here are some food for thought. Do you really want to buy batteries from a company made up of people who steal the manufacturer's designs and use them for their own benefit? Because that's what they're doing, even with very poor quality products.
I stumbled across a site that sold DeWalt replacement tool batteries, Xbox gaming systems, and cutlery. Do you think the company is committed to producing quality tools? Thermal jackets are all the rage right now. Do you really want to put one of these knockoffs on something you wear? Something tells me it's not going to end well.
Look, I know you want to save money. I do too. There are companies in China that make knockoff Apple computers, SpyderCo knives, power tools, batteries, and whatever name brand products they think will sell. They are thieves. They're happy to take your money and don't hesitate to send you a piece of junk in exchange. Even third-party manufacturers, despite their attempts at production quality, can't match the original manufacturer's battery designs. Do yourself a favor and only use genuine manufacturer replacement tool batteries.
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