Milwaukee M18 batteries don’t natively fit DeWalt 20V MAX tools — the connector shapes are completely different. However, third-party battery adapters exist that let you use your Milwaukee batteries in DeWalt tools (and vice versa). This guide covers how these adapters work, which ones are available, the safety risks involved, and whether they’re worth buying.
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Short Answer
Third-party adapters are sold that let Milwaukee M18 batteries fit DeWalt 20V MAX tools, but we have not verified any combination. These adapters are widely available on Amazon and eBay for around $15–$30. However, they bypass built-in safety communication between battery and tool, damage linked to one may not be covered by the tool maker’s guarantee, and they are not part of either maker’s battery system.
How Do Milwaukee-to-DeWalt Battery Adapters Work?
A battery adapter has a Milwaukee-style receptacle on one end and a DeWalt-style connector on the other. We have not verified what circuitry a given adapter contains.
On voltage: DEWALT says its “20V MAX” figure is the maximum initial voltage and the nominal voltage is 18V, which matches the 18 in Milwaukee’s M18 name. That does not by itself make the batteries interchangeable: the adapter still bypasses the communication between battery and tool.
Available Adapters
| Direction | What It Does | Typical Price | Where to Buy |
|---|---|---|---|
| Milwaukee M18 → DeWalt 20V | Use Milwaukee batteries in DeWalt tools | $15–$25 | Amazon, eBay, AliExpress |
| DeWalt 20V → Milwaukee M18 | Use DeWalt batteries in Milwaukee tools | $15–$25 | Amazon, eBay, AliExpress |
Starter packs by platform
As an Amazon Associate we earn from qualifying purchases. Genuine packs only; check the listing matches your platform before buying (affiliate links).
Before you buy: check that the size, fitting/bore and maximum-rated speed marked on the accessory match what your tool’s manual specifies. We have not physically tested these products; listings are compiled from published specifications. These are affiliate links.
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Which batteries fit which tools — cross-brand, adapters & Ah, decoded.
One adapter on sale for this direction is the MIL18DL, sold under the MAKBOS name among others. We have not verified what circuitry these adapters contain.
Safety Risks & Limitations
| Risk | Explanation |
|---|---|
| BMS communication bypass | Milwaukee and DeWalt batteries have onboard Battery Management Systems that communicate with their respective tools. An adapter may not pass this communication through, so the tool may not be able to read the battery’s state, temperature or charge level. |
| No automatic shutoff | If the protection signals do not pass through, the tool may not shut off when the battery is depleted, risking over-discharge and permanent cell damage. |
| Overheating risk | High-draw tools can push the battery into thermal stress. If temperature monitoring does not work through the adapter, there may be no protection. |
| Warranty cover | Milwaukee’s guarantee excludes damage from non-approved accessories or parts; we could not obtain DEWALT’s UK exclusions. Damage linked to an adapter may not be covered. |
| Not compatible with all batteries | Milwaukee’s older V18 batteries are a separate system from M18 (Milwaukee lists the 48-11-1830 as a V18 lithium-ion battery), and some tools have enclosed battery compartments. Check the adapter listing for the packs it names. |
| HIGH OUTPUT and FORGE packs | We have no data on adapters with Milwaukee’s HIGH OUTPUT or FORGE packs; these packs are made for high-draw tools, which are the riskiest use for an adapter. |
When It Makes Sense to Use an Adapter
- You already own one brand and need a single tool from the other occasionally. If you’re a Milwaukee user who picked up a DeWalt tool at a sale, an adapter saves buying into a whole new battery platform.
- Low-power tools only. LED lights, radios, fans, inflators, and compact drills draw less current, but we have not verified any adapter as safe with them.
- Temporary or infrequent use. Occasional use limits your exposure, but it does not remove the risks above. Daily professional use is a different calculation.
When You Should NOT Use an Adapter
- High-draw tools: Circular saws, angle grinders, SDS rotary hammers, reciprocating saws.
- Professional daily use: The warranty and safety risks outweigh the savings.
- Milwaukee FORGE or HIGH OUTPUT batteries on cheap adapters: These premium batteries deliver very high current and cheap adapters may not handle the load safely.
The Bottom Line
Milwaukee-to-DeWalt battery adapters are sold and are affordable. They’re a practical solution for occasional, light-duty cross-brand use. But they come with real trade-offs: bypassed safety systems, possible loss of warranty cover for damage linked to the adapter, and potential battery damage. For anything beyond casual use, buying the correct battery for your tool is the safer long-term investment.
Related Guides
- Every DeWalt 20V MAX Battery Compared
- Every DeWalt 20V MAX Tool and Which Batteries Fit
- DeWalt 20V MAX Charger Compatibility Guide
- DeWalt POWERSTACK vs Standard Battery
- Every Milwaukee M18 Battery Compared
Video Guide
Frequently Asked Questions
The Bottom Line on Cross-Brand Use
While the idea of sharing batteries between Milwaukee and DeWalt tools is appealing, the risks outweigh the convenience for most users. Third-party adapters introduce points of failure, damage linked to them may not be covered by the tool maker’s guarantee, and they cannot replicate the sophisticated communication protocols that each brand builds into their ecosystem.
If you find yourself needing tools from both platforms, the most practical approach is to maintain separate battery collections for each. Both Milwaukee M18 and DeWalt 20V MAX offer comprehensive tool ranges, and investing in a few batteries for each platform is far safer than relying on adapters. Many professional tradespeople successfully run two platforms by keeping brand-specific batteries in clearly labelled bags or cases to avoid mix-ups on site.
For new tool purchases, consider which platform you already have more invested in and try to standardise where possible. Reducing the number of battery platforms you maintain simplifies your workflow and reduces overall battery costs.
Can I put a Milwaukee M18 battery on a DeWalt 20V MAX drill?
Only with a third-party adapter. Milwaukee M18 and DeWalt 20V MAX have different physical connections, but aftermarket adapters bridge this gap. Both are 18V-nominal packs, but similar voltage does not establish compatibility. However, neither manufacturer supports or recommends this approach.
Which direction do Milwaukee-DeWalt adapters work?
Adapters are directional — a “Milwaukee to DeWalt” adapter lets you use a Milwaukee battery in a DeWalt tool. A “DeWalt to Milwaukee” adapter does the reverse. Make sure you buy the correct direction for your needs. Each adapter only works one way.
Is it cheaper to buy an adapter or a new battery?
Adapters typically cost between $15-30, while a new battery costs $50-150 depending on capacity. If you only need occasional cross-platform use, an adapter saves money. But for regular use, buying a native battery is more reliable, safer, and performs better. Adapters are best viewed as a temporary or emergency solution.
How we compile this guide
We cross-reference compatibility details against manufacturer specifications where available, official tool manuals, and the physical standards that govern fitment (bore sizes, arbor diameters, voltage platforms, connector types). We prioritise primary sources over retailer listings, flag anything we can’t confirm, and re-verify the data on a regular cycle. Where we give a buying recommendation, we tell you the reasoning — not just the link. More on our method →
