Understanding Your Zero's Battery
Learn how lithium-ion batteries work, what the BMS does, and how to interpret battery-related data in your logs.
TL;DR
Zero uses lithium-ion NMC cells in a series configuration (28S for most models = ~102V). The BMS monitors each cell's voltage and temperature, manages charging, and protects against damage. Healthy packs show balanced cell voltages (B field <50mV) and consistent SOC tracking.
Lithium-Ion Battery Basics
Zero Motorcycles use lithium-ion batteries with NMC (Nickel Manganese Cobalt) chemistry. This provides an excellent balance of energy density, power output, and cycle life for electric vehicle applications.
Cell Specifications
- Nominal Voltage:3.7V
- Full Charge:4.2V
- Empty (cutoff):3.0V
- Storage Voltage:3.7-3.8V
Zero Pack Configuration
- Cells in Series:28S
- Nominal Voltage:~102V
- Full Charge:~116V
- Cutoff:~84V
Battery Management System (BMS)
The BMS is the brain of your battery pack. It monitors every cell, manages charging, and protects against conditions that could damage the battery or create safety hazards.
BMS Functions
- • Monitor individual cell voltages
- • Track pack and cell temperatures
- • Calculate State of Charge (SOC)
- • Balance cells during charging
- • Control charge current limits
- • Log events and diagnostics
BMS Protections
- • Over-voltage (cell >4.2V)
- • Under-voltage (cell <3.0V)
- • Over-temperature
- • Under-temperature (no charge <0°C)
- • Over-current protection
- • Short circuit protection
State of Charge (SOC)
State of Charge represents the remaining capacity as a percentage. The BMS calculates this using a combination of voltage measurement and coulomb counting (tracking current flow).
SOC vs Voltage (Approximate)
Note: The relationship is not linear — Li-ion cells have a relatively flat voltage curve in the middle range.
Key Battery Log Fields
These fields appear in BMS log entries and indicate battery health and status:
| Field | Meaning | Healthy Range | Warning |
|---|---|---|---|
| PackSOC / SOC | Battery percentage | 20-80% | <10% or >95% |
| Vpack / PV | Total pack voltage | 94-116V | <90V or >118V |
| L / l | Cell low threshold / min (mV) | >3200mV | <3100mV |
| H | Cell max voltage (mV) | <4200mV | >4250mV |
| B | Cell balance delta (mV) | <50mV | >100mV |
| PT / BT | Pack temp / Board temp (°C) | 15-35°C | <5°C or >45°C |
Battery Pack Visualizer
Interactive visualization of a Zero battery pack. Colors indicate cell voltage levels.
Sources:
This is an educational resource. For official battery specifications and safety information, consult your Zero Owner's Manual.