The EV Power Lithium Battery Management System is designed specifically for large format Lithium Iron Phosphate (LFP, LIFEPO4) cells. It can work with almost any brand of cell with minimal modification.
LiFePO4 batteries have two specific maintenance requirements:
- Cell balancing is required to maintain a consistent state of charge across all cells of a battery. LiFePO4 batteries are not self balancing
- Cell voltage monitoring and battery control for over/under voltage conditions. This is essential to ensure safety and long battery life
THE EV POWER SYSTEM IS THE SIMPLEST BMS THAT ACCOMPLISHES BOTH OF THESE FUNCTIONS
BMS SYSTEM OVERVIEW
The EV Power LiFePO4 BMS consists of two parts:
1) Battery Control Unit (BCU) – one BCU per battery pack, monitors the battery voltage and the cell module loop and takes action to prevent charging or discharging if there is a fault.
2) Cell Modules – one per cell which can work as passive shunt balancers and link together via our proprietary one wire NC Loop to provide a signal to the BCU if one or more cells is outside its safe voltage range.
The heart of the EV Power system is the analog passive cell balancer/monitor module. Simple and elegant. There is one cell module for each cell in a battery. The cell modules perform the function of balancing and monitoring the cells. Each cell module has a green LED to indicate OK status (when on) and a red LED to indicate when the module is “balancing” the cell.
EV Power developed its unique one wire system that connects each cell module to the next. This provides two ends that interface back to a battery control unit which controls charge and discharge.
Cell Module Features:
- Epoxy Encapsulated to prevent moisture and dust interference. Also keeps out bugs, dropped spanners, loose cables, nuts and fingers!
- Gold plated cell terminal connectors for perfect connection and professional looks.
- One wire link between cell modules. We invented the system.
- Low profile, does not even protrude above terminal bolts.
- Up to 2A shunt current capacity (CBM400).
- No heat buildup when regulating, no bulky hot resistors.
- Small footprint the actual circuit is the size of a postage stamp! It does not interfere with mounting hardware.
- Low power consumption 3+ years to drain a 100Ah idle cell.
- Reverse polarity protected.
- Simple to install and easy to understand.
- Sizes suitable for most prismatic LiFePO4 cells.
EV Power cell modules go through a three stage burn-in testing procedure during manufacture and then a confirmation test just prior to dispatch. Four stages of testing, each and every cell module.
LFP 3.2V Cell Module Datasheet
NCM 3.7V Cell Module Datasheet
BATTERY CONTROL UNIT
The Battery Control Unit is the brains of the BMS. It checks the cells status and also the overall battery voltage, current and temperature. Based on this information it can directly control charge, discharge and also make State of Charge calculations. EV Power manufactures a variety of battery control units from extremely simple (BCU-MICRO08) to remote display models for up to 60V operation.