==== High Voltage Relay Wiring – with Precharge ====

⚠️ **Disclaimer – Safety First!** \\
The wiring diagrams and connection examples provided here are **suggestions only** and may not cover all edge cases or safety requirements.\\
All high-voltage components must be installed and verified by a **qualified electrician** or professional installer.\\
Incorrect wiring or misuse can lead to **severe damage, fire, or personal injury**.\\
The manufacturer assumes **no liability** for damages resulting from improper installation or handling.

Below is the recommended HV wiring setup for systems using **3 relays** and **precharge functionality**:

{{:mk3:screenshot_2025-04-07_170957.png?740x358}}

=== 🧩 Components: ===

  * **HV Battery:**  Provides the main power
  * **HV Fuse:**  Protects the system from overcurrent
  * **HV Relays (3 total):**
      * **Precharge Relay:**  Connects via precharge resistor to slowly charge input capacitors
      * **Positive Relay:**  Main high-side connection to the load
      * **Negative Relay:**  Switches the low side (Battery -)
  * **Precharge Resistor:**  Limits inrush current when first connecting to the inverter
  * **Current Shunt:**  Measures total current flow
  * **Inverter / Load:**  Final consumer of the HV power
  * **Chassis connection (''E''  pin):**  Must be connected to battery chassis – ideally with 2 separate wires
=== 🔌 BMS HV Connector Pins: ===

  * **B+ / B-:**  Connect directly to the battery
  * **O+ / O-:**  Connected after the relays, represents the //output side//
  * **E:**  Earth/Chassis connection
''⚠️ Important: The **precharge path**  must always lead through the shunt to ensure current measurement during precharge. The **positive and negative relays**  must remain **open**  during precharge phase and close only after precharge completes.''

👉 This wiring ensures proper current monitoring and safe soft-start of the system.

==== Relay Control ====

The GRNbms MK3 directly controls all three HV relays using integrated 12 V outputs.\\
Each relay is connected via its **dedicated connector**:

   * **HV Relay Positive**
  * **HV Relay Negative**
  * **HV Relay Precharge**
=== Requirements: ===

  * Relays must have a **12 V coil**
  * **No external power supply**  is needed – the BMS provides the 12 V directly
  * Each output is internally protected and current-limited

👉 We recommend using relays with economizer to avoid unnecessary load on the BMS power supply

''✅ Just plug in your relays – the BMS handles power and timing automatically''