First time EV buyers are often worried about range anxiety - that feeling of being caught short on flat batteries miles from a charging point. Yet also of concern is the actual life of the battery pack. Experience with mobile phones, tablets and laptop computers has taught consumers that, over time, the batteries powering them can lose efficiency, resulting in the need for more frequent charging. So should you be worried? Well the good news is EV cells are more resilient than you’d think, plus there are ways to make sure your car’s batteries will survive better than most.
Electric car battery life
After range anxiety, battery life is one of the most common concerns for people making the jump from internal combustion-engined cars to EVs. All batteries degrade over time and with use, meaning they become less efficient as they age and, ultimately, the range of your car is reduced. Furthermore, battery technology doesn’t come cheap, and by the time the cells are in need of replacement they will cost far more to buy than the car will likely be worth - which is why we tend to replace mobile phones in their entirety rather than replace the battery pack. Yet it’s not all bad news, because there are ways to increase the lifespan of your car’s battery, keeping it healthier and more efficient for longer. More importantly, while performance may degrade over time, ultimately the cells should still be providing at least 70 percent of their capacity even after 200,000 miles. As an example, a number of Tesla Model S taxis operating from Gatwick airport racked up over 300,000 miles each over three years, with all retaining at least 82 percent of their batteries’ health.
Why does an electric car battery lose charge or degrade?
Continual advances in battery technology mean that issues surrounding degradation of performance are being reduced all the time. However, even the latest lithium-ion cells aren’t completely immune to losing performance over time, with a number of factors playing a role. Perhaps the biggest single contributor to the decline in efficiency is the cycle of use and charging. Frequent draining of the cells followed by a full charge can, over time, damage the battery’s ability to maintain its optimum energy storage - it’s why manufacturer’s typically recommend charging only to 80 percent and never letting the range drop to zero miles.
Rapid charging also plays a part, because channeling so much electrical energy and so quickly generates much higher temperatures in the battery pack. Liquid cooling of the cells helps mitigate this, but use a rapid charger frequently and over time these extreme heat cycles will cause damage to the lithium ion packs. In a similar but less extreme way, cars that are used in hotter climates tend to suffer a subtly greater reduction in performance than those in cooler conditions.
How can I care for my electric car battery?
Happily, there are ways you can help preserve the power and efficiency of your battery over time. One of the major ways of protecting the cells is by carefully managing the charging and discharging of the cells, which in an ideal world means trying to avoid capacity dropping below 20 percent and not adding more than 80 percent when charging - above the latter figure is when batteries tend to get hottest, which takes a toll on the cells’ delicate chemistry.
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As a matter of fact, I recently replaced the battery in my Samsung galaxy S5 and it cost £9. So no need to replace the phone.
Seems to me that the best way to mange your electric car battery is to top up overnight at home using a 13 amp socket - effectively a trickle charge. This should usually suffice if you're only doing short trips, as the battery will never get desperately low so the oft-quoted 40 hour charge times will not apply.
This will also avoid using a dedicated home phone charger. These chargers will in future allow power companies to bill you more per unit because they know it's for car charging - the extra to be passed on to the government in lieu of fuel tax
In short then...
To preserve battery life, you should only use 60% of the available capacity, avoid rapid chargers and avoid using the full performance of the vehicle.
It seems that battery longevity hasn't so far been an issue, but with increasing pressure on manufacturers to extend EV range and reduce charging time (and with incresed availability of rapid chargers), perhaps it will be a problem in future?
Interestingly this week's Autocar quotes a usable capacity of the MG5's battery of 48.4kwh, some 93% of its actual capacity. Perhaps the article above is being too cautious in its advice?
This is also why wireless charging of cars is an appalling idea with current technology. The waste and losses are huge compared to plugging in a cable so the energy required goes up (think of the impact on the national grid and emissions) and the heat generated destroys the batteries quickly.