Can You Use Harbor Freight Batteries On Milwaukee Power Tools?

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Harbor Freight owns many power tool brands, including Bauer, Hercules, Atlas, Warrior, and more. To accompany each of these brands' power tools, they all have their own lines of battery packs. Harbor Freight only sells products from its own brands and approved partners, so you won't be able to purchase battery packs for a Milwaukee tool, for example.

Even if you can't get Milwaukee-branded batteries for your tools, you might think that one of the many battery brands sold at Harbor Freight would fit them. Sadly, this is not the case. The technology that governs a Milwaukee battery pack is incompatible with every single battery type sold at Harbor Freight. As nice as it would be to get a cheaper battery than one of Milwaukee's $169 Redlithium packs, the chain has nothing to offer you in that department. Theoretically, you may be able to circumvent that problem through the use of a third-party battery adapter, but not only would doing that require a decent bit of sleuthing, it could end up causing problems for both your batteries and Milwaukee tools.

Putting Milwaukee batteries and tools aside, none of the batteries offered by Harbor Freight's power tool brands are compatible with one another. Every brand's battery uses a different setup of connecting rails and power terminals, and while they may seem similar at a glance, the minute details make all the difference. For example, Hercules and Bauer tools are not compatible with one another, as a Bauer battery has six terminal notches on top, plus connecting rails with a slight circular curve, while a Hercules battery has four small notches and one large one, plus rails with a sharper angle. These differences would prevent the batteries from attaching to tools outside their system or delivering power.

The same is true for Milwaukee's batteries and tools. Milwaukee's 18V Redlithium system uses a proprietary connection consisting of four terminal notches nestled between two large borders, which swoop back in oval-shaped rails. This is what Milwaukee tools are built to receive, and no other battery pack sold by any other brand, including those from Harbor Freight, would fit them. Even if you could somehow force a Bauer or Hercules battery onto the rails, the differences in terminal shape would prevent the tool from recognizing the battery, and it wouldn't receive any power.

If it seems unfair that every power tool battery utilizes an exclusive system, there are apparently many others who share that sentiment. Many individuals and third-party brands have taken to developing their own solutions to this problem: battery adapters. These devices, which are frequently sold on platforms like Amazon, are designed to latch onto a battery's terminals on the bottom, then connect to a tool's receiver with the right terminals and rails.

In theory, this is an ideal solution, allowing you to use whatever batteries you want with your Milwaukee tools. However, there are several substantial problems. Firstly, all battery adapters are strictly 1-1 devices. If you wanted to use a Bauer battery on a Milwaukee tool, for instance, you would specifically need to obtain a Bauer-to-Milwaukee adapter, which wouldn't work with any other battery brand sold by Harbor Freight. You may not be able to find an adapter for the precise battery combination you're looking for.

More concerningly, using battery adapters puts your batteries and tools at potential risk. All power tool batteries, including both Milwaukee's M18 and M18 FUEL lines, are equipped with a circuit board that carefully regulates power delivery, communicating directly with the tool to get you optimal performance. Using an adapter bypasses the circuit board, forcing power through with no particular goal in mind. Your tools may turn on, but their performance could be underwhelming compared to what they normally get. Worse, they may receive far too much power, overloading and burning out. If your batteries or tools are damaged while using a battery adapter, neither Harbor Freight nor Milwaukee will give you service or replacements, as using third-party accessories is a warranty violation.