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Maintaining EV battery health

By autotech-nic on July 19, 2021

Alex Johns, from battery data specialists Altelium, on how you can advise electric car owners to keep their Electric Vehicle battery in good health

The most valuable component of an electric vehicle is its battery; yet few owners know how to keep the battery heart of their cars in good health.

As drivers tend to be primarily focussed on battery range or charge, manufacturers tend to give little information about how to keep an EV battery in good shape on a daily basis. In fact, EV owners are more likely to be given advice on finding charging points or battery range, which is useful, but perhaps not as valuable long-term.

By offering EV owners good advice on battery health, you’re offering them a long-term benefit – and in turn, building a good reputation amongst the growing EV community.

Most of us are used to keeping an eye on the state of charge on our smart phones, making sure it is always charged, or discussing the benefits of one big charge versus ‘topping up’ through the day. This is a great comparison to use when explaining battery health to customers. In practice, the same principal applies to the electric battery in your vehicle but obviously with vastly more energy involved.

In some ways, understanding battery State of Health (SoH) is the key to longevity. Battery state of health is described as the current capacity of your battery as a percentage of its original capacity. Alex Johns oversaw the Tesla taxi trial at Gatwick airport before he joined the battery data specialists Altelium, and he knows more than most about battery SoH:

“When I oversaw the trial of five Tesla electric taxis stationed at Gatwick Airport in 2019, each vehicle had 300,000 miles on the clock when the trial concluded, but the batteries were still at 82% State of Health (SoH),” he explains. “They were still working really well with many years life left in them. There is no question over the quality of the batteries, but we were given clear guidelines on how to use them and charge them.”

So, what can you tell EV drivers to do, to best maintain battery ‘heart health’?

Alex first suggests fast charging on DC chargers for no more than 30% of all your charging. Charging has a large impact on battery health so try to charge at home wherever possible, using a household plug or A/C slow/medium rate charger.

Secondly, try not to let your battery run completely flat, it is best to keep it in the middle range as much as possible where the chemicals in the battery are held at optimal conditions. A car battery computer will be set to do this as far as possible, but drivers can certainly help by not running it down completely.

Additionally, if you find that you are running your battery all the time (for example in a taxi role or delivery operation), then let it rest – not charging or driving – once a week at a moderate state of charge (30-50%).

Another good tip is to keep electric cars in the shade on sunny days. The optimal temperature for a battery is at 21-21.5⁰C and extreme heat or cold will really impact the range of that electric car battery. While extreme cold will reduce battery performance, the effect of heat is more important from a health and longevity point of view.

Altelium uses battery data to facilitate second life uses to electric vehicle batteries, for example in Battery Energy Storage Systems (BESS), through warranties and operational data analytics. Altelium believes good battery management and understanding is the key to maximising the life of batteries and the environmental credentials of electric vehicles.

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