Hercules 20V to Milwaukee 18V Battery Adapter
218,00 kr
Skip to product information
Hercules 20V to Milwaukee 18V Battery Adapter
218,00 kr
Taxes included.
kr 23.00 Shipping to DenmarkZero customs fees. Zero surprise taxes.
Use your Hercules 20V batteries on Milwaukee M18 cordless tools, without buying into a second battery platform. The molded ABS housing keeps it light and hard-wearing, and pure copper contacts keep current delivery steady. Fewer battery systems in the workshop, on the bench or in the van, and no extra chargers to find room for.
Specifications
- SKU
- PTA-HER20-MIL18
- Fits this battery
- Hercules 20V (Lithium-Ion)from Harbor Freight
- Battery voltage
- 20V
- Runs these tools
- Milwaukee M18 (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
- 127 g (4.5 oz / 0.28 lb)
- Colour
- Red, Yellow
- Operating humidity
- 5–95% RH
- Operating temperature
- -10 °C to 50 °C (14 °F to 122 °F)
- USB port
- No
- What's in the box
- Battery adapter
- Warranty
- 12 months after the date of deliveryMore details
- Revision
- Revision 01 (released on March 10, 2025)
Why choose this adapter
- 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.
- Made for the Hercules 20V batteries sold at Harbor Freight, so the fit is the one you already own.
- Covered by a 12-month warranty from the day it arrives.
Hercules 20V and Milwaukee M18 compatibility
It works in one direction only: Hercules batteries powering Milwaukee tools. For the opposite pairing, see adapters that run on Milwaukee M18 batteries.
Compatibility can vary with the exact battery and tool model. Before ordering, confirm that your battery belongs to the Hercules 20V platform and that your tool takes Milwaukee M18 batteries.
Important charging and safety information
This adapter is for powering cordless tools and nothing else. It cannot charge Hercules or Milwaukee 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 Hercules 20V battery.
How it works
-
1. Use the battery you own
Any compatible Hercules 20V battery you already have.
-
2. Slide on the adapter
It goes where the original Milwaukee M18 battery sits.
-
3. Click in and work
No tools, no wiring, no modifications.
Hercules 20V to Milwaukee M18 — Common Questions
My battery says 20V. Can it run a tool rated differently?
Yes, and they are closer than the labels suggest. 20V is what a Hercules 20V battery measures off the charger with no load; 18 V is what it holds in use. Milwaukee M18 tools are built around 18 V. The two numbers describe the same class of battery, which is why the adapter works rather than merely fits.
Will my Milwaukee M18 tool run as long on a Hercules 20V battery?
Runtime comes from the battery, not the adapter — a 5.0Ah Hercules 20V 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 Hercules 20V battery or my Milwaukee M18 tool?
Used with undamaged, compatible equipment it is not expected to. Hercules 20V 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 Milwaukee M18 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 Hercules 20V battery off the adapter and charge it on its own charger.
My Hercules 20V gear came from Harbor Freight. Is that the same platform?
Yes — Harbor Freight is where Hercules 20V is sold, so a battery or tool bought there is the platform this adapter is built for. What matters is the socket, and Harbor Freight stock is the reference for it.
Does it work with third-party Hercules 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 Milwaukee M18 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 Milwaukee M18 tool?
127 g (4.5 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.