Mapped out the Hart 40V battery pinout, sharing what each pin does

[Thomas Martinez]

Been poking around in my Hart 40V pack to see what the hell each pin on the connector does since I’d like to either rebuild it or use it in a side projects. Took a while to figure out what was what on the pack, but I finally did. Thus, sharing what I found in case others is also wondering what the heck is going on with this connector.
The minus and plus pins is self-explanatory; the minus is the negative terminal and the positive is the positive terminal. The tool uses the ID pin to identify the battery. The D pin allows data communication between the tool and the battery pack. The TH pin is the thermistor pin that allows the tool to monitor temperature of the battery. Finally, the C1-C9 pins are the junctions between the cell groups that allows the Battery Management System (BMS) to balance the cells within the battery pack.
Not exactly sure what protocol is used on the D pin communication line yet. Not sure if the ID pin is just a resistor or if it’s more involved on the Hart battery packs. Has anyone scoped the data line on one of these batteries or even pulled the BMS off one of these packs? Also, has anyone tried using the battery without connecting the ID pin? Does the tool refuse to start or does it work in a limp mode? Let me know what you’ve found with your Hart or other 40V packs.

 

[Distinct Dugon]

the ID pin on most of these walmart-tier packs (hart, hyper tough, kobalt 40v in some cases) is just a resistor to ground. Tool reads the voltage divider and goes ok cool youre a real battery. Ive bypassed em with a 10k before and it worked fine on a hart blower, ymmv depending on tool firmware.

 

[European Met]

Did you scope the D line yet? Curious if it’s UART over the D line or if it’s something like SMBus.

 

[Bewilder]

hart is just rebadged devault internals from what ive seen tearing them apart. The BMS board layout is almost identical to some of the older 40v devault stuff. Wouldnt suprise me if the protocol is the same too.

 

[Distinct Dugon]

Did you scope the D line yet? Curious if it’s UART over the D line or if it’s something like SMBus.

if its anything like the chervon-made packs (which hart is, chervon makes them for walmart) then the D line is a 1-wire ish protocol at low speed. Its not standard SMBus. Youll need a logic analyzer not a regular scope to make sense of it.

 

[European Met]

if its anything like the chervon-made packs (which hart is, chervon makes them for walmart) then the D line is a 1-wire ish protocol at low speed. Its not standard SMBus. Youll need a logic analyzer not a regular scope to make sense of it.

interesting, so chervon rolled there own? thats annoying. Guess ill hook up the saleae this weekend and see what falls out. As far as polling the battery, its either constantly or only at the time of startup of the tool, correct?