Stanley V20 to Hercules 20V Battery Adapter

Use your Stanley V20 batteries on Hercules 20V cordless tools, without buying into a second battery platform. Power passes straight through: Stanley V20 and Hercules 20V share the same 20V rating. 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. It also carries battery protection electronics (BMS) inside.

Specifications

• Fits this battery Stanley V20 (Lithium-Ion)
• Battery voltage 20V
• Runs these tools Hercules 20V (Lithium-Ion) from Harbor Freight
• Tool voltage 20V
• 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 125 g (4.4 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
• Built-in BMS protection Yes
• What's in the box Battery adapter
• Warranty 12 months after the date of delivery
• Revision Revision 01 (released on October 5, 2025)

Why choose this adapter

• Your Stanley V20 battery and Hercules 20V tools run at the same voltage, so the adapter changes the fitting rather than converting anything.
• A Battery Management System inside the adapter cuts power before the battery is drained too far — protection your battery may not have on its own.
• 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.
• Covered by a 12-month warranty from the day it arrives.

Stanley V20 and Hercules 20V compatibility

It works in one direction only: Stanley batteries powering Hercules tools. For the opposite pairing, see adapters that run on Hercules 20V batteries.

Compatibility can vary with the exact battery and tool model. Before ordering, confirm that your battery belongs to the Stanley V20 platform and that your tool takes Hercules 20V batteries.

Important charging and safety information

This adapter is for powering cordless tools and nothing else. It cannot charge Stanley or Hercules 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 Stanley V20 battery.

Before you buy