The rundown on charging your EV’s battery

0 0 November 10, 2022 Edit this post

by Paul Murrell

ONE of the questions we get asked regularly is how to prolong the life of an EV battery? Should you keep it on the charger when it’s not being used? Should you only charge it to 80 per cent? Should you avoid using fast chargers?

There is plenty of advice about the best way to get the longest life from those expensive batteries, and not all of it is accurate.

Most car companies recommend charging the battery to 80 per cent of its capacity. Not only is this good practice to get maximum life out of a battery, it also overcomes that annoying habit of EV batteries taking an inordinate amount of time to get that last 20 per cent of charge into them. The default Tesla setting is to allow the battery to charge to 90 per cent and then stop, although Elon Musk has suggested in a tweet that Tesla owners would be better served charging to 80 per cent.

A Tesla expert recommends charging the battery daily. Jeff Dahn, Tesla Industrial Research Chair and Professor of Physics and Atmospheric Science at the University of Dalhousie, Nova Scotia (he could recharge his battery while listing his full title!) is one of the leading battery experts. He suggests charging to 70 per cent, and only charging to the full 100 per cent before setting out on a long trip. Tesla recommends keeping your battery charged at between 50 and 90 per cent of its capacity for normal driving (you can set the charge limit in the car, or using an app). Before a long trip, charge the battery to 90 per cent and one hour before departure, put it back on the charger to get it to 100 per cent. It’s fiddly and frustrating, but the aim is to avoid the battery sitting at 100 per cent for any significant amount of time. On the road, charge the car to 80 per cent and avoid letting the charge drop below 20 per cent. This will not only extend the battery’s life, but will be faster than trying to charge it to 100 per cent (which takes significantly longer than charging to 80 per cent).

Another good approach is to charge your car at home as much as possible.

Fast charging will reduce battery life, and your home charger is slower. A well-maintained battery pack (one that isn’t drained to zero or regularly charged to 100 per cent) can last up to 400,000km; one that is abused will show signs of degradation within 150,000km. Historical data indicates that a Tesla battery will lose about five percent of its capacity after 80,000km. And since the battery pack is by far the most expensive part of an EV, looking after it will save you considerable expense.