Hilti Battery to Milwaukee Tool Adapter: Does It Work?

Hilti professional tools run on their own battery platform, distinct from the consumer systems most people know. If you already own Hilti 22V packs and need to run a Milwaukee M18 tool for a single job or to avoid buying into a second battery system, a small third-party adapter bridges the two. It clamps onto your Hilti pack and presents an M18-shaped mount to the tool, drawing power directly from your existing cells without any rewiring.

Why the voltage already lines up

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Hilti markets its packs as “22V,” but that is the no-load peak. Under load, the real voltage is approximately 21.6V—nominally 18V class, the same category as Milwaukee M18. Both use lithium-ion chemistry and deliver roughly the same terminal voltage to the tool. A Milwaukee M18 motor expects an 18V-class supply, and a Hilti 22V pack provides one, so the electronics see a compatible input.

The only obstacle is the physical foot. Hilti 22V (B22 format) and Milwaukee M18 use different mechanical interfaces. Hilti packs sit in a different holder, and the terminal positions differ. The adapter exists solely to translate one mechanical interface into the other and to route power and sense contacts to the correct pins on the tool side.

What the adapter does not do

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An adapter is a tool-use bridge only. You cannot charge a Hilti battery through it. There is no path for a charger to talk to the pack’s battery-management system across the adapter, and forcing the issue can damage the pack. The routine is straightforward: run the M18 tool from the Hilti pack, then remove the pack from the adapter and charge it on its own Hilti charger.

It also sits outside both manufacturers’ endorsement. Neither Hilti nor Milwaukee officially blesses cross-brand adapters, and using one can void the warranty on the M18 tool. That is a real consideration if the tool is new and expensive. For a used or inexpensive tool, the warranty risk matters less.

The bigger practical limit is heat. An adapter adds contact junctions between the cells and the motor, and each junction has resistance. On a drill, driver, light, or small saw, the current is low enough that this is never a problem. On a high-draw tool such as a large circular saw or a high-torque impact wrench, sustained current can warm the adapter contacts faster than they dissipate heat. Keep adapters off those tools and use a native M18 pack instead.

What it costs you in performance

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Even on a tool the adapter handles safely, expect a small penalty. The extra contact resistance shaves a little off peak power and can trip the tool’s low-voltage cutout slightly earlier under heavy load than a native pack would. For most jobs you will not notice. If you are pushing a tool to its limit, you will feel the difference, which is another reason the adapter suits light and medium work rather than the heaviest cuts.

The adapter also changes the tool’s balance. It stacks the Hilti pack below where an M18 pack would normally sit, adding height and weight at the base. In a tight battery well or recessed grip, the combined height can foul, and the tool may not stand upright on its battery the way it would with a native pack. None of this is a dealbreaker for occasional use, but it is worth a test fit before you commit to the setup for a long session overhead or in a cramped space.

Choosing an adapter that fits

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Hilti adapters are less common in the aftermarket than adapters for mainstream consumer brands, and they tend to cost a bit more. The DEWDYS HLT22MIL Adapter for Hilti 22V B22 Battery to Milwaukee M18 Tools is a representative option at around 22 dollars and is designed specifically for the Hilti 22V B22 format. When you compare listings, check three things: that the seller explicitly lists Hilti 22V or B22 on the battery side and M18 on the tool side (direction matters, as the reverse adapter is a different part), that the housing has a positive latch so the pack does not wobble loose under vibration, and that recent buyer photos show clean, solid terminal contacts rather than thin stamped strips.

Verify your Hilti pack is the B22 format before ordering, as Hilti has used other battery designs over the years. Older or region-specific Hilti packs may not fit. Skip any listing that claims you can charge through it or that markets itself for high-draw applications like large saws. Those claims either misrepresent the product or signal the seller does not understand its limits.

When it is worth it, and when to just buy the pack

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For a contractor or tradesperson who already owns Hilti 22V batteries and wants to run a handful of M18 tools occasionally, a 22-dollar adapter is a sensible way to avoid buying into a second battery system. It earns its keep on drills, drivers, lights, and similar low-to-medium-draw tools.

If you are leaning hard on a demanding M18 tool every day, or you depend on that tool for work, the runtime penalty, the warranty question, and the heat ceiling all point the other way. At that point the cost of a genuine M18 pack buys you full performance, charging support, and the manufacturer’s backing, which is the better trade for a tool you use constantly.