Understanding how the pinout functions under different scenarios is crucial if you are attempting to adapt the battery for other uses. In the Tool
Hart is a brand of power tools and outdoor equipment owned by Walmart. Their 20V lithium-ion battery platform is designed to provide a reliable and efficient power source for various tools, such as drills, saws, and lawn equipment.
: A control pin that manages communication between the battery's internal management system (BMS) and the tool/charger.
. These aren't just for show; they are the "balance leads" used during charging to ensure every individual cell inside the pack stays at the same voltage—roughly 4V, 8V, 12V, and 16V respectively. A Spark of Life Max remembered a trick from the Hart community Hart 20v Battery Pinout Diagram
You cannot simply connect wires to the and [ - ] terminals to run high-drain custom projects without understanding the BMS behavior. Over-Discharge Protection
At first glance, a Hart battery pack appears straightforward. A closer look reveals that it uses five metal terminals instead of the traditional three, a design choice that makes it technologically advanced and significantly safer than older battery designs. This article provides a comprehensive guide to the , breaking down the function of each pin, how to identify them, and how this system interacts with tools and chargers.
If you connect a HART battery to a non-OEM charger, the charger will see no ID signal and refuse to charge. You cannot bypass this by simply applying 21V to B+ and B- – most HART BMS boards will permanently lock the output (fuse blows or FET opens). : A control pin that manages communication between
| Pin Number | Label | Function | |------------|--------------|------------------------------------------------------------| | 1 (Left) | | Battery Positive (+), 20V Max (21V hot off charge) | | 2 | CH or ID | Charge enable / Thermistor or ID resistor (depends on model) | | 3 | C or S | Communication (SMBus Data line) – talks to charger & tool | | 4 | B- Sense | Negative sense / Cell tap (sometimes unused) | | 5 (Right) | B- | Battery Negative (-), ground |
Remember: If you just need the basic pinout for jump-starting a battery, focus on and B+ (right large slot) . For anything involving charging or data, treat the ID pin with respect. And always prioritize safety over a few dollars’ worth of saved cells.
The Hart 20V battery interface features a slide-on design with a row of recessed female slot connectors. When looking directly at the battery terminal interface with the latch facing up, you will see four distinct metal terminal slots. A Spark of Life Max remembered a trick
You don’t need the data lines to discharge a Hart battery carefully. You only need B+ and B-.
Modern power tool batteries have evolved far beyond simple energy storage. The Hart 20V lithium-ion series is built around an integrated . The BMS is a small circuit board inside the battery case that constantly monitors the pack's vital signs. Its job is to prevent overloading, overheating, and short-circuiting, ensuring both durability and user safety.
Disclaimer: This article is for informational purposes only. Modifying batteries or building adapters carries risk of fire, injury, or property damage. Always follow manufacturer safety guidelines.