greenworks 40V battery circuit help?

Batteries, Chargers, and Battery Management Systems.
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timmy66   100 mW

100 mW
Posts: 42
Joined: Jul 12 2016 1:07am

greenworks 40V battery circuit help?

Post by timmy66 » Jul 21 2019 3:34pm

I'm trying to make a battery to replace a Greenworks 40V battery. I've searched a lot.

There are 4 connections from the battery : + , - , C , and Ohm (Omega).

+,- are as thought.

C appears to ground to - when the tool is operating.

Ohm reads ~2.6V when tool is operating. The resistance on it is (at the battery) ~20k Ohms. When the battery is connected to the tool, the resistance is ~5k Ohms.

If the Ohm connector is not connected (eg. just 40V straight to the tool), the tool (trimmer) shuts off after 5seconds or so. Shunting Ohm to ground lets the tool operate for 15seconds or so.

Of course most tool battery packs use this as a thermistor. I've tried substituting in a 20k resistor for the Ohm (20kOhms from Ohm to ground). This doesn't change anything. Shorting it lengthens time.


And thanks.

The replacement battery I'm connecting to the tool doesn't need help with LVC / temperature sensing as it has it's own BMS.

Other notes : current drains are ~12A max (~500W total observed).

suti1984   1 µW

1 µW
Posts: 1
Joined: Sep 01 2020 2:11pm

Re: greenworks 40V battery circuit help?

Post by suti1984 » Sep 01 2020 2:13pm

have you a you could solve the problem. have the same

StinkyGoalieGuy   100 W

100 W
Posts: 289
Joined: Apr 23 2008 3:53pm

Re: greenworks 40V battery circuit help?

Post by StinkyGoalieGuy » Sep 02 2020 1:21am

The Omega port needs to see a series of logic signals.

Have a look at this thread here:

I was able to decode the logic pattern for the 60v greenworks motor and regenerate it with an arduino. If you have access to a friend's 40 volt greenworks tool and battery, you can decode the pattern for the 40v greenworks battery as well.

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