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EVs and climate change

We're told that EVs will help reduce the rate of climate change.

Instead of guzzling huge quantities of fossil fuels and belching CO2 from their exhausts, EVs will instead sip gently from the font of renewable energy and ensure that mother nature's vital cycles are protected from harm.

Sounds great -- although in some countries, a fair amount of the electricity used to recharge an EV comes from fossil fuel and even here in New Zealand we're still dependent on the stuff for at least some of our power generation.

Unfortunately, I think there's about to be a real race take place, between increasing global temperatures and EVs.

What am I talking about?

Well the heatwave in the UK and Europe right now has highlighted some deficiencies in the EV concept, sometimes with rather dramatic results.

The problem with lithium-ion batteries, of the type most often used in EVs, is their aversion to high temperatures.

Although, with careful management, they can be operated safely at temperatures up to 60 degrees C, the maximum temperature for safe recharging is generally limited to 45 degrees or so. Fast charging requires that temperatures are maintained below 40 degrees.

Now imagine it's a scorching hot day, such as has been the case in Europe and the UK over the past week or so. With ambient temperatures hovering around 40 degrees it becomes a little bit marginal to drive your EV over bitumened roads which are baking in the sun and may actually reach as much as 30 degrees hotter (70 deg C).

The road surface will be busy radiating that heat straight into the battery tray of any EV driving on it. Then there is the natural heating caused by resistive losses within the battery itself.

Yes, almost all EVs these days have temperature management systems (cooling) for their batteries but these systems only have a finite capacity to cope and the consequences when that capacity is reached can be catastrophic. At best, your EV will go into limp-mode or simply force you to pull over and stop -- while it desperately tries to cool the battery.

A worse scenario probably doesn't need describing.

Even if an EV is able to regulate its battery to less than 60 degrees while in use, zooming down the highway, there's the issue of charging, in particular - fast-charging.

If you're on a trip and need to stop for a quick charge along the way, you may find charging currents hugely limited in high temperatures. The vehicle's battery cooling system will be having to work hard to bring the battery down below ambient and to a level where fast-charging can be safely performed.

There was electric bus fire in the UK last week which also damaged some charging points at a depot. One can only wonder if this may have been triggered by the recent heatwave.

I've heard from at least one Tesla driver who says that the UK heatwave hasn't affected his car but I suspect that some less capable brands may find themselves suffering very real performance and reliability issues if 40 degree daytime temperatures become the norm in Western nations.

Carpe Diem folks!

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