A recent article by Quartz explores the connection between fast charging of electric vehicles and battery degradation over the lifetime of the car. It’s still unknown how many years it will take before a steep drop in battery capacity is seen, but for now, experts know that over the first few years of life, the battery will experience a steady, shallow decline.
They state that “on average, EV batteries lose about 2.3% per year—or 23 miles for an EV with a 200-mile range over five years.” The article also mentions that not all brands decline at the same rate. To see the comparison of different makes and models, view Geotab’s EV battery degradation comparison tool: https://storage.googleapis.com/geotab-sandbox/ev-battery-degradation/index.html
The main driver of battery degradation was tied to higher ambient temperatures and DC fast charging. Therefore, the thermal management system of the battery pack is critical.
There are three main types of cooling used in EVs on the road today:
1. Passive Air-Cooling
A battery designed with passive air-cooling relies on outside air and the movement of the car to remove heat from the battery through heat radiation. This is the lowest cost method and leads to higher uncontrolled temperatures in the battery pack as it relies on the ambient temperature, which varies greatly.
2. Active Air-Cooling
Utilizing fans or blowers, active air-cooling is a step forward in thermal management while still being relatively inexpensive. Depending on the design, ambient or conditioned air is used. This still leads to higher overall temperatures in the battery pack as the response to convective cooling is still quite slow and access to every cell is troublesome.
3. Liquid Cooling
Removing heat through conduction is the most efficient means of thermal management. Liquid cooling systems have come down in both cost and weight. The key to efficient liquid cooling is limiting the amount of thermal resistance from the battery cell to the liquid cooling plate. This is typically handled using liquid dispensed two-component gap fillers.
Using Thermal Management Materials to Limit Thermal Resistance
While it’s crucial to select the right type of cooling for your design, another important aspect to consider is the use of thermal management materials. Commonly used thermal interface materials are liquid-dispense, cure-in-place gap fillers and pre-cut, pre-cured thermal gap pads, both of which have their own benefits. High thermal conductivity and low viscosity gap fillers have become more and more popular over the few years to assist in removing heat from EV battery packs.
To learn more about our thermal management offerings, visit lord.com/CoolTherm.