The new version of the tool adapter from the same ebay seller seems to work in all tools now. Check out my new updated video below:

   • DeWalt 20v Battery to Hercules Tool Adapte...  

You can get the new revised adapter from below (I have no affiliation with the seller):
https://www.ebay.com/itm/204569997187



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Old Description Below:

Dewalt Battery to Hercules Tool/Battery Adapter - Review

Edit: Read my pinned comment for the latest update on the adapter.

Purchased the adapter from Ebay https://www.ebay.com/itm/204569997187.

Doesn't currently work on all Hercules tools but it does work on some tools, see below. I believe HF has updated the signal algorithm communication between the tool and the battery in some of their newer tools thus why the adapter won't work with some tools. Cracking the digital signal may be nearly impossible going forward. The only other way to guarantee that a dewalt battery or any other battery will work in a Hercules tools is to use a donor board from a Hercules battery.

Leave a comment if you find the adapter works or doesn't work for something please

List of tools the adapter doesn't work for:
Brushless Bandsaw (confirmed by me)
Brushless Angle Grinder (confirmed by seller)
Brushless 7 in. Variable-Speed Rotary Polisher/Sander (confirmed by comments)
Brushless 1/2 in. impact not sure which specific model though, I believe Ultra given the High-torque was confirmed to work (confirmed by comments, will run but only for about a minute)
Brushless Nibbler (confirmed by ebay feedback)
Hercules Spotlight (confirmed by ebay feedback)
Brushless Vacuum Pump (confirmed by ebay feedback)

List of tools the adapter does works for:
Brushless Compact Reciprocating Saw (confirmed by me)
Brushless 3/8 in. Compact, 4-Mode Impact Wrench (confirmed by seller)
Brushless Die Grinder (confirmed by seller)
Brushless Router (confirmed by seller)
Brushless 1/2 in Hammer Drill/Driver (confirmed by seller)
Brushless 1/2 in. Variable Speed Right Angle Drill (confirmed by seller)
Brushless 6 1/2 in. Circular Saw (confirmed by seller)
Brushless 1/4 in. 3-Speed Impact Driver (confirmed by me)
Brushless Variable-Speed Oscillating Multi-tool (confirmed by seller)
Brushless 5 in. Random Orbit Sander (confirmed by me)
Brushless 1/2 in. High Torque Impact Wrench (confirmed by comments)
Hercules 20v Fan (confirmed by ebay feedback)
Hercules flashlights (not the spotlight, confirmed by ebay feedback)

I also reached out to other battery adapter companies and they replied that haven't been able to get adapters to work with Hercules tools.

TIMESTAMPS
00:00 - First Impressions
02:25 - Adapter Testing
04:04 - 2nd Adapter Testing
05:07 - Look At Internals