System

The wider system and it’s requirements are fundamental to the design of a battery pack. This means we need to understand the power electronics and how they operate, what they require, their failure modes and any legislative requirements.

Different applications have different system requirements, duty cycles and use cases.

  • Mobile applications
    • Passenger Cars
      • MHEV
      • HEV
      • PHEV
      • BEV
    • Commercial Vehicles
    • Railway
    • Aviation
    • Maritime Applications
    • Industrial Vehicles
    • Construction Vehicles
    • Light Electric Vehicles
    • Bikes
    • Defence
    • Racing
    • Aerospace
  • Stationary (BESS)
    • Off-grid Systems
    • Home Storage
    • Industrial Storage
    • Charging buffer
    • Grid Booster
    • Grid Balancing
  • Consumer electronics
    • Smartphone and tablet
    • Wearables
    • Computer & Notebook
  • Industrial and medical
    • Power Tools
    • Medical Devices
    • Microelectronics

Battery Pack Metrics

A Pugh Matrix is a good way of making a high level comparison between applications and the key pack metrics.

In the case of mobile consumer products such as a mobile phone the lifetime of the battery is perhaps not as important as it would be in the case of a grid storage system. The mobile phone has a 2 to 3 year life before most are upgraded. A grid storage system needs 20 years of operation.

Road Vehicle Power Demand

Let’s look at the road vehicle power demand for the simple steady state condition. We will look at the tractive effort and power required:

  • Aerodynamic forces
  • Rolling resistance
  • Acceleration
  • Gradients
  • Hotel loads

Auxiliary systems and their power consumption in a vehicle especially an electric vehicle have a big effect on the vehicle range. The Range is decided by the battery capacity in kWh. Battery capacity is primarily used to provide traction power through AC or DC motor. Efficiency of motor, drivetrain and battery can tell you how much power is available out of the total for propulsion. But there are also many auxiliary systems in an electric vehicle which consume kW power which in term reduces the power available for traction.

Cold Climate EV Range

There are a number of factors that will impact the vehicle range and it is not totally due the battery as this is a two axis problem with the vehicle energy consumption also playing it’s part. Hence, let us break this into battery energy and vehicle energy consumption at the highest level and then list the factors under each.

  • Vehicle energy consumption
  • Battery energy

Mixed Chemistry Battery Pack

A look at the power density versus energy density graph. This shows that high power tends to be at the expense of energy.

Hence, the question: “what if we could combine two technologies?”.

Battery Value Chain

The battery value chain looks at the whole eco system from mining the raw materials through to recycling.

Battery versus System Voltage

When we look at the battery versus system voltage we have to remember that these are working together. In fact we have to look at the complete system and all components to ensure they can work together over the maximum and minimum voltage range. This will normally be the maximum charge voltage and the minimum voltage will be the under load transient condition.