Hart 20v Battery Pinout Diagram ((install)) ★ Free Forever
The Hart 20V battery uses a 5-pin interface similar to the DeWalt 20V Max system, which is why many third-party adapters for these brands are interchangeable. The primary terminals are located on the far left and right, with three communication and balancing pins in the center. 🔋 Main Pin Configuration
Looking at the battery from the top with the connector facing you (from left to right):
B+ (Positive): The far-left terminal. Provides full pack voltage (nominal 18V, peak 20V).
TH (Thermistor): Temperature monitoring pin. Connected to a 10k ohm thermistor grounded to B-. If this reading is missing or out of range, the tool or charger may shut down for safety.
ID (Identification): Tells the charger/tool the battery's capacity or type. Usually a 100k ohm resistor grounded to B-.
C (Control): Used by the battery's internal management system to communicate with the tool or charger.
B- (Negative/Ground): The far-right terminal. The common ground for the pack. ⚡ Technical Voltage Readings
When testing with a multimeter against the Negative (B-) terminal on a fully charged pack, you should see: B+ to B-: ~20V (Full capacity) TH to B-: ~0V (unless active) ID to B-: ~0V (resistance-based)
C to B-: ~20V (on some models, this pin carries voltage to signal the tool) 🛠️ Internal Balance Points (C1–C4)
If you open the battery casing, you will find contact points labeled C1 through C4. These are for "balanced charging," allowing the Hart Charger to monitor each of the five individual lithium cells: C1: ~4V (1st cell) C2: ~8V (2nd cell) C3: ~12V (3rd cell) C4: ~16V (4th cell) ⚠️ Critical Troubleshooting Hart 20v Battery Pinout Diagram
Resetting "Dead" Batteries: If your battery shows a permanent failure code (LEDs flashing in a specific pattern), it might be "undervolted." Some users "jumpstart" these by momentarily connecting a healthy 20V battery's B+ and B- to the dead one's B+ and B- to raise the voltage enough for the charger to recognize it.
Compatibility: While the pinout is physically identical to Bauer 20V (Harbor Freight), they are not always electronically compatible without an adapter due to the internal ID resistor differences.
Understanding the Hart 20V battery pinout is essential for DIY projects, such as creating battery adapters or troubleshooting charging issues. These lithium-ion batteries typically feature five primary external terminals used for power delivery, temperature monitoring, and internal cell balancing. Hart 20V Pinout Configuration
The standard Hart 20V battery interface includes five main pins. Looking at the battery connector with the terminals facing you, they are generally identified as follows: B+ (Positive Terminal):
The main power output. When fully charged, this should measure approximately relative to the negative terminal. TH (Thermistor): temperature monitoring
. This pin allows the charger or tool to sense if the battery is overheating during use or charging. ID (Identification): This pin communicates the battery type
to the tool or charger to ensure compatibility and prevent overcharging. C (Control):
A control pin that works with the battery management system (BMS) to regulate power flow. B- (Negative Terminal): The main ground/negative power return. Internal Balance Contacts
Internally, the battery contains additional contact points (often labeled C1, C2, C3, and C4 ) used for balanced charging The Hart 20V battery uses a 5-pin interface
. These measure the voltage of individual cells in the series: Common Troubleshooting and Usage Low Voltage Protection:
Note that low-voltage cutoff is often handled by the tool, not the battery itself. When using these batteries for DIY projects, ensure you include a Low Voltage Disconnect to prevent permanent battery damage from over-discharge. Resetting the Battery: If a battery fails to charge, placing it on a Hart 4-Port Fast Charger for a few minutes can sometimes trigger a reset. Compatibility:
Hart 20V battery typically uses a 5-pin layout to handle power delivery, temperature monitoring, and tool communication. Understanding this pinout is essential for DIY projects like building battery adapters or troubleshooting charging issues. Hart 20V Battery Pinout Configuration
Based on measured voltages and technical teardowns, the five main pins are generally arranged as follows: Description + (Positive) Main Power Out Primary 20V output to power the tool. TH Thermistor
Monitors battery temperature during charging/use to prevent overheating. ID Identification Communicates battery specs/type to the tool or charger. C
Often used for low-power communication or balance charging signals. – (Negative) Ground / Return The common negative terminal for the circuit. Key Voltage Measurements
When testing a fully charged battery with a multimeter, you can expect the following readings between pins:
Positive (+) to Negative (–): ~20V (Standard operating voltage).
Positive (+) to TH / ID: ~20V (Commonly measured across these internal circuits). Negative (–) to C: ~20V. Q1: Can I charge a Hart battery with
Internal Balance Points: For advanced repairs, internal cell taps (C1-C4) usually show incremental voltages of approximately 4V, 8V, 12V, and 16V relative to the negative terminal. Safety and Troubleshooting Tips
Battery Resets: If your battery refuses to charge despite correct voltages, placing it on a Hart 20V 4-Port Charger for a few minutes can sometimes trigger a manual reset.
Adapters: Many users utilize third-party adapters to run Hart tools with other brand batteries (like DeWalt), but ensure the adapter correctly maps the protection pins (TH/ID) to avoid damaging the tool's motor.
Thermal Safety: Never attempt to bypass the TH (Thermistor) pin, as it is the primary safety measure against battery combustion during rapid charging. Hart 20v Battery Pinout Wiring Diagram
Q1: Can I charge a Hart battery with a bench power supply using the pinout?
A: Only if you have the BMS communication protocol decoder. Without it, the BMS won’t enable charging. Stick to the official charger.
Hart 20V Battery Pinout Diagram: A Complete Guide to Terminals, Wiring, and Troubleshooting
If you own Hart power tools—the popular brand carried exclusively by Walmart and known for providing excellent value—you know the convenience of the interchangeable 20V lithium-ion battery system. But what happens when a battery stops charging, your tool loses power intermittently, or you want to build a custom adapter to run another device?
The answer lies in understanding the Hart 20V battery pinout diagram.
In this deep-dive guide, we’ll break down every terminal on a Hart 20V Max battery pack, explain what each pin does, provide a clear wiring diagram, and show you how to use this knowledge for repairs, DIY projects, and troubleshooting.
Where to Find Official HART 20V Battery Diagrams
HART does not publish engineering schematics. However, these resources are helpful:
- Lithium Batteries 101 (YouTube channel "HART Mods & Repairs")
- Battery University (BU-302: Configuring Battery Management Systems)
- Walmart’s HART replacement parts – Sometimes the terminal block is sold separately with labeled pins.
For exact voltage curves and thermistor tables, you can reverse-engineer your own battery using a multimeter and a temperature gun.