Everything you need to know about EV batteries

We want to help all drivers make more conscious decisions when choosing their next vehicle and become better educated on the possibilities in store when choosing an electric vehicle. This guide covers all of the information that prospective buyers would want to know when starting to research EVs, such as:

    • What type of battery is used in an electric car?
    • What is the size of an electric car battery?
    • What is the lifespan of an electric car battery?

It is important to remember that the way you maintain your electric car battery will affect its performance, range and lifespan. Before getting into the guide, we would always recommend being mindful of how you use and charge your battery, keeping it in a garage to maintain a constant temperature and avoid exposing it to extreme temperatures.

What type of battery is used in an electric car?

There are three types of rechargeable batteries that are suitable for electric car use: lead-acid batteries, lithium-ion (Li-ion) batteries, and nickel-metal (NiMH) batteries.

Lead-acid batteries

Benefits:

  • As they have been used in all types of vehicles since the 19th century, lead-acid batteries are cheap to produce and widely understood by most mechanics.

Disadvantages:

  • They produce dangerous emissions whilst being used and can potentially explode if overcharged.

Nickel-metal (NiMH) batteries

Benefits:

  • Given their high energy density, a lot of energy can be packed into a smaller battery.
  • They are easy to recycle as they do not contain any toxic metals

Disadvantages:

  • Generate a lot of heat during fast-charges
  • High self-discharge (losing their charge when not being used) of around 50%
  • Battery performance can degrade if stored at a high heat

Lithium-ion batteries

Benefits:

  • Lightweight
  • Higher energy density than NiMH and lead-acid batteries, ideal for storing lots of energy to power electric vehicles.
  • Lithium-ion batteries have a much lower self-discharge rate (the likelihood of batteries losing their charge when not being used) than other rechargeable batteries.
  • Some experts maintain that lithium-ion batteries the best contender for powering electric cars.
  • Though they used to be the most expensive type of rechargeable battery, their cost has plummeted in recent years, making them economically viable.

Disadvantages:

  • Lithium-ion batteries require protection from being overcharged. Luckily, most battery management circuitry means they can be left on charge and will cut the supply once the battery is full.

What is the size of an electric car battery?

Below is an example of the average number of units of energy that different size electric car batteries can carry.

Metric Small (subcompact) cars Mid-sized family sedan Luxury Tesla models
Battery kWh 30-35kWh 40-65kWh 65+kWh
Typical range 99 miles 155 miles 375-mile range for Tesla S Model

 

The reason that Tesla models have oversized batteries boasting 60-100kWh is for their infamous extended driving range and high performance. However, for a 60kWh electric car battery, the size and weight required to get 250 miles of EV range, drivers will have to bear a pack weight of nearly ½ ton of battery.

Given the fixed size of a vehicle, EV manufacturers face many challenges in accommodating for larger batteries to provide more range whilst not compromising on space for passengers.

What is the lifespan of an electric car battery?

Lifespan is one of the main factors that makes drivers reluctant to switch to an EV. However, advancements in technology mean that the latest electric car batteries have a longer lifespan than ever before. Most manufacturers offer 100,000 mile/8-year warranties on their EV batteries.

However, EV battery warranties are varied in length across the market. For example, BMW has an eight-year (100,000 miles) warranty and will repair lost capacity below 70% for free during that period. Meanwhile, Tesla offers an eight-year, unlimited-mileage warranty on their batteries.

There are four main triggers that can hinder the lifespan of an electric car battery:

Overcharging or high voltage

Overcharging your electric car battery can cause it to overheat. It is also harmful because of the chemical changes it can cause inside the battery. If you keep your battery constantly fully charged and plugged in, it will build up an internal resistance that can cause its lifespan to reduce.

Overheating

The heat caused by charging your electric car battery or keeping it fully charged or high ambient temperature can reduce the capacity of a lithium-ion battery.

High discharge and charge current

Pulling too much current from your electric car battery for a short amount of time can have detrimental effects on its lifespan. For example, selecting Ludicrous Mode in Tesla Model S allows the car to get from 0 to 62mph in 2.6 seconds. When drivers select this mode, a warning is given on the Model S car screen to explicitly tell drivers that it will negatively affect their electric car battery’s lifespan.

Deep discharge

The battery in an electric car will last longer if you avoid draining the majority of power in one drive. Heavily draining your battery can affect its lifespan. It’s advisable for electric car batteries to operate between 50-80% charge, rather than using it from 100% to 20% in one go.

Tips to increase the lifespan of your electric car battery

    • Charge between 20% - 80% - Going beyond these limits can increase the rate of degradation of the battery
    • Don’t leave it charged at 100% for too long – again, the battery will degrade with time
    • Reduce the number of charging cycles
    • Reduce your Charging Speed where possible and drive efficiently – reduces the load on the battery and keeps it healthier.

It is important to note that as EV batteries and thermal management systems improve, these problems will eventually disappear. You can trust at Tonik that we will report on updates to the industry and give our members refreshed advice on how to take the best care of their EVs.

How do you charge an EV battery?

From July 2019, all government-funded home EV chargers must use smart technology that can help reduce high peaks of electricity demands. This means that charging an EV battery has never been simpler.

Our new ‘zappi’ eco-smart EV chargers from myenergi allow drivers to charge their EV with their solar panels. Zappi can detect when solar energy is available and charges when possible to help reduce EV charging costs. Our eco-smart EV chargers can also monitor household energy consumption whilst charging to balance any conflicting demand. In a rush? Zappi’s boost function also gives drivers superfast charging so they can get off in no time.

Find out more about our new top of the range EV chargers and in-house installers that are Rated 5* Which? Trust Traders now.

 

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