Can You Use Milwaukee Batteries On DeWalt Tools?

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The primary reason that most major hardware brands utilize unified, rechargeable battery systems is convenience. It's nice to have a cordless power tool, as well as being able to just quickly snap on a fresh battery pack when one runs dry. Of course, if you're engaged in a bout of lengthy, strenuous handiwork, you will run out of batteries for your tool of choice eventually. Let's say, for example, you're using a DeWalt battery-powered tool, such as a power drill, on a large project and have already exhausted all the DeWalt-branded batteries you had on standby. What if you had another brand's batteries, let's say Milwaukee's, ready and waiting for one of your other tools?

As nice as it would be to just grab a strong Milwaukee battery off the cradle and snap it onto your DeWalt tool, reality is rarely so accommodating. Even if you have a Milwaukee battery with a comparable level of power output and capacity to the DeWalt batteries you were using, it simply won't work with a DeWalt tool. Every hardware brand has its own proprietary battery connections, preventing one brand's battery pack from locking onto the battery receiver of another brand's tool. The only potential way to circumvent this limitation would be to use an unofficial, third-party battery adapter, but using these kinds of unsanctioned devices could cause your tools to perform erratically or fail entirely, not to mention void your warranty.

Milwaukee and DeWalt's power tool battery systems, M18 and Max, respectively, are conceptually very similar. The M18 system delivers 18V, while the Max system delivers 20V. However, DeWalt's 20V batteries are effectively the same as 18V batteries, which is why they're still referred to as 18V outside the United States. If they could connect, they could still transfer power. Notice, however, that we say "if they could connect." It is within that particular facet of the batteries' designs that we encounter the problem.

If you compare similar Milwaukee and DeWalt batteries, such as the M18 18V 5Ah and the 20V Max 5Ah models, you can see the hiccup on top of each pack. Every power tool battery pack has a panel on top, with connecting rails. The panel houses the power transfer terminals, usually concealed within several small divots, and the connecting rails allow the pack to slide onto a tool's receiver. The M18 battery has a recessed center with five divots housing its terminals, plus a pair of rounded, fang-shaped rails. The Max battery panel also has five divots, but they jut further outwards like long teeth, and its rails bend at sharper angles.

Due to these differences in construction, there's simply no way to connect a Milwaukee battery to a DeWalt tool. The rounded rails wouldn't be able to slide onto a DeWalt tool's receiver, and even if you could somehow secure the pack in place, the recessed shape of the terminal panel would prevent the terminals from actually connecting to those on the tool. If the terminals aren't perfectly lined up, the battery can't deliver any power to the tool.

It may feel a little unfair that you can't use one brand's batteries with another brand's tools, but you must remember that this choice is made for safety and legal reasons. One brand can't know exactly how another brand's batteries function, and if they tried to connect their products together without the other brand's consent, it'd invite a legal firestorm. All that said, if you absolutely insist upon using your Milwaukee batteries in your DeWalt tools, there is technically a way to facilitate that: a battery adapter. Various third-party brands make unofficial adapter accessories that can be clipped onto the top of one brand's batteries and attached to another brand's tools. These adapters are commonly sold on online storefronts like Amazon and eBay.

While Milwaukee-to-DeWalt battery adapters are available, using one may be potentially unsafe. Milwaukee's batteries are equipped with internal circuitry that directly interfaces with a connected tool to optimize and regulate the flow of power for safe, efficient usage. When you connect a battery to another brand's tool via an adapter, that circuitry is completely overridden, forcing power to flow in an unoptimized manner. This could result in undervolted, low-power performance in the tool, or worse, a severe power overload that could end up burning out the tool's motor. If either your battery or tool is permanently damaged while using an adapter, neither Milwaukee nor DeWalt will offer any kind of service or replacements, as you violated both of their warranties by using unsanctioned accessories.