Should I only charge my EV to 80 per cent every time?
Broadly speaking, this is a good thing to do – not only will it save you a bit of money, especially if you’re using public charging, but it can help extend the useful life of your battery. Research by Alteium, a company that provides after-market warranties for electric car batteries, shows that lithium-ion chemistry (the most commonly-used electric car battery chemistry thus far) responds best to being charged to 80 per cent, and not being allowed to fall below ten per cent charge.
The fact is that every time you use a battery – whether that’s charging or using it to power the vehicle – you’re degrading it slightly, and electric vehicle batteries are generally considered to be past their best once they’ve lost between 20 and 30 per cent of their original capacity, which is why car makers tend to offer warranties which guarantee such performance for the first eight years or 160,000km. The good news is that, so far, batteries are in general performing much better than was originally anticipated.
The other good news is that lithium-iron phosphate (sometimes called LFP) batteries are gaining in popularity – BYD, the giant Chinese car maker, uses only LFP batteries, while Ford will shortly launch a Mustang Mach-E with an LFP battery – and are much more robust. At the cost of a little less energy storage per size and weight of battery, LFP batteries can, for the most part, be charged to 100 per cent pretty much as often as you like without (so far, anyway) causing any serious issues.
Your EV questions answered: Am I better to drive my 13-year-old diesel until it dies than buy a new EV?
Your EV questions answered: Is it okay to leave an electric car sitting for a while? For how long?
Can I really do a long journey in an electric car?
EV Q&A: Is it possible to reduce the environmental impact of building an electric car?
Can an EV battery be fixed if it’s damaged in a crash – or does it need to be replaced?
Generally speaking if your EV has been in a crash big enough to damage the battery (which is usually located directly under the passenger compartment and well away from the front and rear crash structures) then it will have to be scrapped. It’s possible that individual cells might be repairable, but pretty much any insurer will immediately write off such a car and its battery, because of the potential danger of a thermal runway fire from a damaged battery. In fact, insurer AXA is calling for new legislation, or an extra element to the independent Euro NCAP crash tests, to highlight this potential battery vulnerability, and has even recommended that car makers should fit additional underbody armour: “for example by providing the underbody with a titanium plate or similar materials with high resistance”.
Can you replace a few cells in a battery or do you need to replace the entire unit?
Yes, you absolutely can and this is how most electric car batteries will be repaired, as opposed to replaced, in the future. This is actually one of the key concerns flagged up by AA Ireland. In a survey of Irish drivers, it found that the majority reckoned that electric car batteries only last for 100,000km (not the case) and that any damage or degradation to one part of the battery pack means an instant and total replacement of the entire pack.
Jennifer Kilduff, Head of Marketing & PR for the AA said: “It is disappointing to see that these myths are continuing to circulate. Modern batteries have sophisticated Battery Management Systems that increase the life of the batteries to not just many years, but potentially a few decades. When they complete their purpose in cars, they will be used in energy storage projects, before finally being recycled. It also needs to be pointed out that an EV battery is not just one big chunk of metal. It is made up of many modules that get combined into a battery pack. In most instances you would not replace the whole battery if there was an issue, you’d replace the individual modules at a fraction of the cost.”
What’s the realistic range for my EV?
How long is your piece of string? Sorry to be vague, but that answer involves a huge number of variables. We’ll try to give as useful an answer if we can.
EVs fall, broadly, into three categories when it comes to battery size – small (up to a around 50-55kWh capacity), medium (60-80kWh) and large (bigger than 90kWh). While you have to work in all of the imponderable variables – such as your own personal driving style, where you’re driving (town? country? motorway?), the weather, the traffic conditions and so on – we can come up with a rough average of ranges.
So for small battery cars, the quoted official range is likely to be around 400km, and the realistic day-to-day range, allowing for all those imponderables, to be closer to 300-320km. As with fuel economy, some drivers will do better, some will do worse.
For medium-sized battery models, the quoted range is likely to be around 500km or just over, with a realistic range of around 400-450km. For reference, the bestselling EV in Ireland is the Volkswagen ID.4, which uses a 77kWh battery and which has, in our hands, a real-world observed range of around 450km against a claimed range of 535km.
When you get into bigger battery models, the picture becomes cloudier as you’re dealing with increased weight, not just from the size of the battery itself, but also because these bigger-battery cars are more likely to be luxurious models with high-end fixtures and fittings. So the results are more mixed.
These cars are likely to claim at least 550km, and often more than 600km, but perform far less impressively in real-world conditions. So, the big BMW i7 claims a range of 621km but we struggled to get more than 450km out of it. Conversely, the Mercedes-Benz EQS boast a range of more than 750km, but will easily do more than 600km in real-world conditions. The big, heavy Audi Q8 e-tron is probably the worst offender here – against a claimed range of 555km, we couldn’t get it to deliver more than 400km, and often saw indicated range on a full charge of around 360km.
The best advice is to not go high-rise. SUVs are inherently less efficient than sleeker saloons, and again VW provides a good example here. Using the same 77kWh battery as the ID.4 SUV, Volkswagen’s sleeker ID.7 saloon boasts a range of 615km, and will easily provide more than 500km of running in real-world conditions.
Will my EV run out of juice if I get stuck in traffic?
It could happen but it’s very unlikely to, unless you get caught in traffic with only a single-digit percentage charge and it’s a massive traffic jam. Research has shown that, when stationary with air conditioning or heating running, an EV will consume around 1-1.5 kilowatt-hours of energy.
Given that even the smallest EV batteries hold around 45kWh of charge, and assuming you’ve hit the back of this notional traffic jam with more than 50 per cent charge, you can sit there for at least 15 hours before your battery will run flat, possibly longer. In other words, you’ll need a sandwich or a wee long before your battery gives up.