: Measures around 20V against the Positive terminal, and 0V against the Negative terminal. The Hart battery charger reads the fluctuating resistance across this pin to temporarily pause charging if the pack gets too hot or cold. 3. ID (Identification) Terminal
Hart batteries are NOT designed to be compatible with tools from other brands. Although the physical form factor is different (Hart uses a slide-in pack [15†L45-L46] while Ryobi has a distinctive upward stalk [15†L40-L42]), it's the electronic communication protocol that ensures your safety. The BMS electronically "locks" the battery to Hart tools and chargers [16†L42-L44].
When looking directly at the interface of a HART 20V lithium-ion battery , you will see for metal receptors. There is physical space for a sixth slot, but it remains empty without any metal contact inside. hart 20v battery pinout diagram better
| Terminal Label | Function | Voltage to B- (Idle) | Critical Note | | :--- | :--- | :--- | :--- | | | Positive Rail | ~20V (18.5V nominal) | Never short to B- | | B- | Ground | 0V | Common reference point | | T | Temperature Sense | ~1.5V - 2.8V (varies) | If grounded, the charger faults. | | C | Clock Signal | ~3.3V (Pulsing) | Logic level voltage | | D | Data Signal | ~3.3V (Pulsing) | Carries battery health/cycle count |
Working with lithium-ion batteries involves serious risks. They store a significant amount of energy, and mishandling can lead to short circuits, fires, or explosions. Before you start: : Measures around 20V against the Positive terminal,
Additionally, you should never short the battery terminals or attempt to bypass the BMS. Lithium‑ion cells can deliver very high currents – a short circuit can cause sparks, burns, or a fire.
If your battery isn't working properly (showing a false full charge), a "reset" can sometimes help by jump-starting a locked BMS. Here are three methods from Tool Croze : ID (Identification) Terminal Hart batteries are NOT designed
Interestingly, the charger interface itself uses only four of the five pins – it does not connect to the positive terminal directly. Instead, it uses the mystery horizontal pin (which may be the Control or another signal line) to manage charging. This design ensures that charging only occurs when the BMS confirms it is safe to do so.
| Negative to ... | Voltage Reading | | :--- | :--- | | Negative | 0V | | TH | 0V | | ID | 0V | | Control (C) | 20V | | C1 | 4V | | C2 | 8V | | C3 | 12V | | C4 | 16V |
: Hart batteries share some DNA with Ryobi (both are TTI brands), but they use different physical terminal connections. Adapters are available to use batteries with Hart tools if needed. Hart Tools Safety Warning