If you are an E-Bike rider using VRLA (Valve or Sealed Regulated Lead-Acid) batteries or an electric car owner with the latest Lithium-Ion battery packs, its important to understand and mitigate the effects of heat on your pack.
Generally coastal/sea-side cities and towns like Mumbai, Chennai, Kochi and cities in lower altitude like Delhi, Ahmedabad, Thiruvananthapuram, Kolkatta experience hot weather for more than 6 months of the year.
Cities and towns on an altitude like Bangalore, Pune and to an extent Hyderabad have pleasant weather except for the summer months.
So if you reside in any major city or town in India there is no escaping heat.
Valve Regulated Lead Acid Batteries and Heat
Each 8°C rise in temperature cuts the life of a sealed lead acid battery in half. A VRLA battery for stationary applications that would last 10 years at 25°C would only live for five years if operated at 33°C. The same battery would desist after 2½ years if kept at a constant desert temperature of 41°C. Once the battery is damaged by heat, the capacity cannot be restored.
Lithium-Ion Batteries And Heat
Lithium-Ion chemistry is extremely sensitive to high temperatures. Heat causes lithium-ion battery packs to degrade much faster than they normally would. Battery performance begins to suffer as soon as the temperature climbs above 35°C. A temperature above 35°C affects the battery pack performance instantly and even permanently if it lasts many months.
To combat the extreme temperature effects and keep batteries within their optimal temperature range, automakers around the world use thermal management systems relying on either air or liquid cooling. Liquid cooling is generally more likely to preserve a battery’s capacity than air cooling, though performance variations will occur depending on how well a battery management system was designed to control temperature. The Tesla Model S, the Ford Focus EV etc all use liquid cooling to keep the battery packs at a constant temperature of 25°C.
Unfortunately Indian auto makers have not used liquid cooling in any of the EV's sold in the country.
So its imperative for EV users, to take certain precautions and to understand and mitigate the effects of heat on your battery pack in your EV.
Here are certain tips that can be implemented to take care of your batetry pack in your EV.
- Better not to charge upto ‘100 percent’
In hot weather, using an 80 percent charge can significantly improve battery health. As a battery is charged up, its internal resistance increases, making it harder to put more energy into the battery. The harder it is to charge, the more heat is generated in the process, raising the temperature of the battery.
In hot weather, using an 80 percent charge can significantly improve battery health.
- Avoid deep discharges
Running a battery to almost low levels of charge also impacts on battery life and health.
Because power is a function of current multiplied by voltage, and a discharged battery has a lower voltage than a fully charged one, an almost-empty battery has to provide a higher current for a given power level than it did when fully charged.
Increasing the current drain on the almost-empty battery generates more heat, raising the temperature of the battery.
- Reduce Power Consumption
The more energy you pull from your EV's battery pack, the harder it has to work and the hotter it will get. On hot days, resist the temptation to drive hard and fast. Instead, make sure you accelerate smoothly and calmly, draining as little energy from the battery pack as possible.
In really hot weather, if you are using an electric car, you’ll of course want to use the air conditioning, but wherever possible, pre-cool your car when it is plugged into the socket.
Not only will it pre-cool the cabin, but it will dramatically reduce the strain on the battery pack.
- Invest in covered parking
Where possible, try and park in underground parking garages with good ventilation, away from direct sunlight. Not only will it reduce the temperatures your EV's battery pack is subjected to, but it will give the battery pack time to cool down before you next use it.
Also if you have to park your EV in the open, park the vehicle in a spot used by a car or a truck, so that the bottom surface of the parking lot is cooler and will radiate less heat energy onto your EV.
- Charge your EVs at night
Night times are cooler in most Indian cities, so its always better to charge your EV at night, preferably between 12 am and 5 am when it is cooler outside.
- Don't charge your EV immediately after parking it
Its recommended to let the EV cool down for an hour or so and then charge. For example, if you get home from work at 7 pm. You could get back to the parking lot at 10 pm and start the charging process. Heat builds up during discharge (when u drive) and heat builds up when u charge the pack. So its a good practice to enhance the life of a battery pack, especially in our hot summers.
Avoid quick charging
Quick charging works by delivering DC power directly to the battery using special cables that bypass on-board charging equipment. We don't have any major quick charging infrastructure yet in India. Mahindra Reva has showcased DC Quick charging stations at the Auto Expo. These stations will soon be operational in the coming months and it would be tempting to charge your EV fast. Again heat is a problem here , the faster the rate of current that is applied during the charging process, the more heat is generated. So its good to use these stations rarely rather than regularly and preferably avoid using it in our hot summers!
Indian EVs do not have any sort of major thermal management systems in place for the batteries. So its imperative to take precautions in our blazing summers. I hope these simple tips from pluginindia would take care of the battery pack in your clean and quiet EV!