Parking under shaded spots, minimising use of fast chargers are some of the ways to protect EV batteries

Several reports have confirmed that EV battery packs degrade quicker under exposure to prolonged high temperatures (fig. 1). The rate is accelerated at temperatures exceeding 45 deg C, especially when the consensus seems to be that the ideal operating temperature for EVs is 21.5 deg C.

Fig. 1: Drop in EV driving range with changes in temperature | Image: Geotab

The problem is that a battery pack houses inherently reactive metals and the system has a degree of chemical reactions that are active at all times. It is designed in a manner that minimises the loss of the metals (for both the cathode and the anode) when the vehicle is stationary or in storage. But high ambient temperatures increase the total energy in the system because the metals’ ions absorb the excess heat and are able to move about more freely.

Their higher total energy also makes it more difficult for them to be absorbed at the other terminal, and the greater forces with which they strike the component surfaces leads to an elevated rate of physical wear and tear. This is irreversible and the batteries lose a significant amount of range in the immediate and the long term.

How to protect EV batteries from heat

The key to minimising a permanent loss to batteries’ performance is thus to shield them from the heat in the first place. This can be done through a combination of the following:

  • Parking under shaded spots
  • Keeping the battery charged to around half of its capacity if the vehicle will be in medium to long term storage
  • Using the vehicle’s cooling system to cool the battery pack before it is taken out for a drive on a warm day
  • Using battery packs that are made of lithium iron phosphate, rather than lithium-ion
  • Driving well within the vehicle’s design limits to lower the strain on the batteries
  • Minimising the use of fast charger

The last point is still not a cause for concern for most Indian customers, as the country does not have many fast-charging stations to begin with. Yet it must be kept in mind by EV owners as the frequent use of the process could degrade battery performance, since it pumps in current at a rate at or close to the battery’s maximum input capacity.

The fact that the above steps work can be found in an example from Austin, Texas, where even after owning an electric truck for around 10 years, the owner did not find any drop in its driving range or performance.

Implications for India

Unfortunately this issue does not bode well for India. It seems that the country is experiencing more frequent and more extreme heatwaves with every passing year, which will put a greater strain on its EVs’ battery cooling systems. Finding a parking spot that’s not directly under the sun in the country can also be a challenge, unless the EV owners have access to charging points that are set up under solar panels, or are shielded from direct sunlight (fig. 2).

Fig. 2: Parking EVs under shaded spots, such as under solar charging points, is ideal when it comes to minimising battery degradation from extreme heat | Image: Ecoflow

Nevertheless, the careful planning of trips and charging the vehicles during the cooler parts of the day would be a good start. The extent to which this issue is tackled will also depend heavily on the quality and the chemistry of the battery packs used by the OEMs going forward.