Milwaukee 18V to Ryobi 18V Battery Adapter
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$41.00
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Milwaukee 18V to Ryobi 18V Battery Adapter
$41.00
Taxes included.
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This adapter lets you power Ryobi 18V ONE+ cordless tools with the Milwaukee M18 batteries you already own. Power passes straight through: Milwaukee M18 and Ryobi 18V ONE+ share the same 18V rating. Built with a durable injection-molded ABS housing and pure copper contacts for steady current delivery. One battery platform across more tools means less spent on batteries and less to keep charged.
See it in action
Specifications
- SKU
- PTA-MIL18-RYO18
- Fits this battery
- Milwaukee M18 (Lithium-Ion)
- Battery voltage
- 18V
- Runs these tools
- Ryobi 18V ONE+ (Lithium-Ion)
- Tool voltage
- 18V
- Housing
- ABS (Injected)
- Terminals
- Copper
- Current rating
- 40A continuous (80A peak at 18VDC for up to 2 seconds)720 Watt continuous at 18V nominal
- Internal wiring
- 5 mm²
- Weight
- 140 g (4.9 oz / 0.31 lb)
- Colour
- Black
- Operating humidity
- 5–95% RH
- Operating temperature
- -10 °C to 50 °C (14 °F to 122 °F)
- USB port
- Yes
- What's in the box
- Battery adapter
- Warranty
- 12 months after the date of deliveryMore details
- Revision
- Revision 01 (released on October 9, 2021)
Why choose this adapter
- Your Milwaukee M18 battery and Ryobi 18V ONE+ tools run at the same voltage, so the adapter changes the fitting rather than converting anything.
- Injection-moulded ABS, not 3D printed — no layer lines to split under load.
- Solid copper terminals, so less of the current is lost as heat.
- 5 mm² internal wiring, rated for 40A continuous with 80A peak at 18VDC for up to 2 seconds, so a high-draw tool is not held back by the adapter.
- A USB port on the adapter, so the same battery charges a phone on site.
- Covered by a 12-month warranty from the day it arrives.
Milwaukee M18 and Ryobi 18V ONE+ compatibility
It works in one direction only: Milwaukee batteries powering Ryobi tools. For the opposite pairing, see adapters that run on Ryobi 18V ONE+ batteries.
Compatibility can vary with the exact battery and tool model. Before ordering, confirm that your battery belongs to the Milwaukee M18 platform and that your tool takes Ryobi 18V ONE+ batteries.
Important charging and safety information
This adapter is for powering cordless tools and nothing else. It cannot charge Milwaukee or Ryobi batteries and must never be connected to a charger of any kind. Always take the battery out of the adapter before charging, and charge it on the original charger made for your Milwaukee M18 battery.
How it works
-
1. Use the battery you own
Any compatible Milwaukee M18 battery you already have.
-
2. Slide on the adapter
It goes where the original Ryobi 18V ONE+ battery sits.
-
3. Click in and work
No tools, no wiring, no modifications.
Milwaukee M18 to Ryobi 18V ONE+ — Common Questions
Will this fit my other Milwaukee batteries?
Only Milwaukee M18 batteries. Milwaukee also sells Milwaukee M12, Milwaukee V18 Ni-Cd, and those use a different socket — same brand, different rail and contacts, so they need their own adapter. Compare the rail on your battery with the photos before ordering.
Will my Ryobi 18V ONE+ tool run as long on a Milwaukee M18 battery?
Runtime comes from the battery, not the adapter — a 5.0Ah Milwaukee M18 battery lasts roughly twice as long as a 2.5Ah one, exactly as it would on its own tool. The adapter’s copper terminals and heavy-gauge wiring are there to keep resistive loss low.
Could this damage my Milwaukee M18 battery or my Ryobi 18V ONE+ tool?
Used with undamaged, compatible equipment it is not expected to. Milwaukee M18 batteries are lithium-ion with a protection circuit built into the battery, and it keeps working through the adapter — it stays in the battery and never moves into the adapter. Stop when the tool slows noticeably rather than running the battery flat, and stop using the adapter if it becomes unusually hot or the contacts look damaged.
Can I charge through the adapter?
No, and it should never be attempted. The adapter carries power one way only, out to the Ryobi 18V ONE+ tool — there is no charging circuit inside it. Connecting it to a charger puts the battery, the charger and the adapter at risk. Always take the Milwaukee M18 battery off the adapter and charge it on its own charger.
Does it work with third-party Milwaukee batteries?
Usually. What matters is the socket, not the badge: if the battery slides on and locks the way an original does, the adapter takes it and the Ryobi 18V ONE+ tool runs. Aftermarket moulding does vary, so if yours looks unusual send us a photo and we will check before you order.
How much does it add to the Ryobi 18V ONE+ tool?
140 g (4.9 oz) and a short extension between battery and tool. You notice it overhead or in a tight cabinet; on a drill or driver held normally it disappears.