The Li-Ion In Winter: What Cold Weather Does To EV Batteries

A number of you will have bought your very first EV in the past 9 or so months (i.e., when the warmer weather began in spring through to autumn). Now that we’re heading into winter, there are some things that you will need to be aware of as the colder days roll around. This is because EVs don’t behave like ICE (internal combustion engine) vehicles.

You may well be glad that you don’t have to sit there and warm up the engine before you get going (although I have to say that most modern ICE vehicles don’t need you to do this – thankfully!). However, you may find the following scenario has happened to you:

You set out on a chilly morning as usual in your PHEV or BEV and head off on your normal commute.  You had topped up the battery as usual the night before and you’ve got plenty of charge.  However, this morning, you notice that the range seems to be much lower than usual, meaning that you have to plan for an extra stop to recharge. Because you’d planned your time according to what you normally do, you don’t have time to stop off and recharge right now if you want to be in time for work, so you plan for an extra stop on the way back home, meaning that you lose out on some family time.  If you’re really unlucky, you have to limp into the charging station on the last dregs of the battery.  You may wonder what on earth happened to drain your battery so quickly – and you will have a fair amount of time to stop and think about this as you wait at the charging station.

In fact, quite a few drivers have found that in cold wintery weather, battery range can drop by as much as 40%.

Now, one of the reasons why your battery may have drained more quickly in cold winter weather is obvious. If it’s a bit chilly, your natural instinct is to turn the heater on so you don’t arrive at work with a dripping red nose and chilly fingers. Obviously, the heat that comes through the climate control system in your EV has to come from somewhere, as the system can’t use the waste heat from the engine, as is the case in ICE vehicles. This heat has to be supplied by the battery, so that puts extra demand on it, meaning that you end up with less range and a battery that drains more quickly.

Now, you could always bundle up in an extra coat, a hat, a scarf and a set of mittens for your drive to avoid using the heater and spare your battery.  However, there are other options.  The first is to make the most of functions such as heated seats.  Although these will also use the electrical energy stored in the battery, it’s a lot more efficient to heat your back and bottom with a heated seat than it is to heat the air enough to get you comfortable.  With some models of EV, such as Tesla, you can also pre-warm your car while it’s waiting on the trickle charge so that it’s nice and warm when you get in, and the electricity used to heat things up hasn’t drained the battery as much as it would have if the car wasn’t plugged in.

However, this isn’t the only reason why your battery drains so quickly in colder weather.  It’s an unfortunate reality that lithium ion batteries sulk when the temperature drops (it’s all to do with the electrochemical reactions going on inside the battery).  You may remember from back in high school science days that you can speed up a chemical reaction by adding heat and slow it down by cooling things down, and the same applies to the chemical reactions that make the battery work.  Because things inside the battery are sluggish, they don’t produce as much power, so your range goes down.  Just to add to the insult, because of this slowed chemical reaction, regenerative braking doesn’t work as well, which also adds up to an extra reduction in the range.

Now, the designers of EVs have been smart enough to know that if things get too cold, the chemical reaction will stop altogether, so they have included a heating system in the battery pack – which, of course, runs off the battery’s own power.  If you, like many others, have set your vehicle up on trickle charge overnight, you may find in the morning that you haven’t got as much charge overnight as you had hoped. This is because some of the energy has gone to heating the battery. Parking the car inside overnight while it charges can help overcome this problem, as this helps the battery stay in the Goldilocks Zone of temperature (not too hot and not too cold but just right).

Another reason why you may not have got as much charge as you had hoped is also a result of the sluggishness of lithium in the cold.  In cold temperatures, the lithium is slow to release its charge and it’s also slow to receive charge as well (charging is just a reversal of the chemical process). This may mean that you have to allow more time to charge your battery, although it’s important to bear in mind that frequently using superfast chargers will shorten your battery’s lifespan.

Some aspects of winter driving are unavoidable.  You probably will have to use the headlights more often in the darker days, along with the demisters to unfog your windows and the windscreen wipers. These will all put extra demand onto your battery.  If winter in your part of the country means strong winds, these will also put an extra demand on your battery, as getting your vehicle up to speed means that wind resistance will have to be overcome.  However, by following the advice in this article, you’ll be able to claw back a little extra range, so you see a drop of only ~10% rather than 40%.

To recap:

• Use heated seats and steering wheels rather than the climate control to stay warm.
• Preheat your vehicle while it’s still charging.
• Allow for extra charging time (and possibly more stops at the charging station).
• Park your vehicle inside overnight.
• Wear warm winter clothes inside the car so you don’t have to switch on the heater.

Choosing The Right Driving Posture

When I learned to drive, I wasn’t told much about correct driving posture apart from ensuring that my feet could reach the pedals (obviously) and that my hands were in the “ten past two” position*. However, as time went on and I drove more, I soon came to learn that there’s more to sitting comfortably, and there’s a reason why car manufacturers take so much trouble with designing seats and making them adjustable in many different ways.

If you’ve felt stiff and sore after driving for a long time, then your driving posture might have something do to with it. Sitting down in a car seat is no different from sitting down in an office chair from some perspectives, and it’s important to allow for regular breaks during a long drive so that you can stretch your legs, etc. – just like you would if you were at work. Your office chair is probably not as comfy and cushy as the driver’s seat, unless you’ve done what I’ve done and converted the seat from an old Ford Falcon into an office chair (it’s a pig to move in and out, though, as I haven’t put castors on it).

Although the idea would be to get up every 20 minutes, we all know that this isn’t always possible when driving (every hour is more like it).  However, you can reduce the strain on your body – and it is strain – from holding in one position for ages by ensuring that you’re sitting correctly. If you’ve felt stiff after a long drive, then this might help you.

Everybody’s body is different, so I can’t give precise measurements and angles.  You may have long legs in proportion to your body, a big bum or a long back.  You may be a massive great big dude over six feet tall, or you may be a petite woman reaching five feet in her high heels.  This means that what’s ideal for you probably won’t be idea for someone else.  In fact, what’s best for you might not even be possible in some vehicles, so always test out the seats before you buy a new car.  This means that in the case of a couple consisting of the big dude and the petite lady, you’ll need to compromise (not ideal) or even buy two cars.

OK, to make sure you’re sitting comfortably, let’s begin with some basics. Take your wallet and/or phone and anything else out of your back pocket, because that will have an effect.  Now take time to find out what a neutral spine feels like.  A neutral spine is not a straight back, as the human spine is supposed to have a nice gentle S-bend shape to it.  Stand up and, if you can, check in a mirror side on.  Ensure that your weight is evenly distributed on both feet and don’t fully lock your knees.  Now imagine that there’s a string attached to the top of your head and that it’s pulling you up. 

For more help with knowing what a nice neutral spine feels like, I suggest chatting to your friendly local physiotherapist, taking up Pilates or both.

Now to get into the car.  Oddly, you need to start with the seat in completely the wrong position and then bring it into the right position.  If you’re doing this for the first time in a new car (or a car that you’re considering buying) then move everything as far as it can go – seat angle, steering wheel and all. Push the seat right back as far as it can go.  Now you’re ready to adjust it.

Let’s start with the seat height. In fact, the seat height is the least adjustable thing in many cars, so if you can’t get the height right, you may have to consider another vehicle. Your hips should be about as high as your knees or just a smidge lower (but not too low).  However, you shouldn’t be so high that you hit your head on the top of the car or that you have to crane your head down to see the instrument panel.  If you are too low down, you can use a cushion to get you high enough.  Also check where the edge of the seat is relative to the backs of your knees. If the edge of the seat pushes into your knees, this will restrict your circulation, and riding in that car will be very uncomfortable. Seriously, this matters.  I once owned a car that did this to me. It was great in other ways but the problem with circulation in the feet and legs was so bad that we sold the vehicle (hope it suited the new owner better). Reach down and see if you can fit two fingers between the edge of the seat and your knees. If you can, you’re all good.

Now bring the seat forward so you can reach the pedals (and the footrest) while keeping your back snugly against the seat.  You should have a small bend in your legs, as locking your legs for long periods isn’t all that good for them.  Your heels (in bare feet or ordinary shoes, not high heels) should be on the ground rather than dangling, and you should be able to push the pedal down with your heel on the floor as the fulcrum of a lever.  It’s possible to buy pedal extenders so you can do this if the car is perfect in every other way.  Of all the things that make driving tiring, an accelerator pedal that you can’t operate with your heel on the floor is the worst, and I’ve driven a couple.

If you can adjust the tilt of the seat, play around a bit until you find the position that gives you a neutral spine.  Women will naturally have a more forward tilt than men thanks to the shape of the female pelvis (high heels were invented to exaggerate this) but not too extreme.  Modern car seats have been designed to prevent “submarining”, which is when someone slides out under the seatbelt during the sudden stop in a crash, but this slightly backward angle isn’t all that good for our backs.  There’s not much you can do about this, so get the tilt as close as you can to what gives you a neutral spine.

Now for the seat back. This should not be at right angles to the ground (straight up and down) but it shouldn’t be so far back that it forces you/allows you to slouch your chest, head and shoulders forward.  Keep that spine in neutral position.  If you have lumbar support, this should sit snugly into your lumbar lordosis (the curve in your lower back just above your pelvis).  Some cars don’t have height-adjustable lumbar support (bad luck), and just have lumbar support that’s adjustable in terms of depth.  If your car doesn’t have lumbar support or if it’s in the wrong place for your body (I have a long back in proportion to my legs, so this happens to me a lot), then a lumbar cushion is worth buying and fitting to your car.

Moving on up, make sure that your shoulders can press against the back of the chair, then adjust the head rest. The head rest is supposed to be a head rest, not a neck rest, so sit with a neutral spine and ensure that the head rest touches the back of your head.

Now to adjust the steering wheel. You should be able to get both hands on it with a slight bend in your elbows – driving with straight arms puts strain on your shoulders and neck.  The best position isn’t “ten to two”, as I was taught, but quarter past nine (nine and three) down to seven and five.  Adjust the height of the steering wheel to suit you.

In a perfect world, we’d be able to customize everything so that it suited our bodies perfectly, especially when it comes to female bodies. Traditionally, car seats have been designed to fit the average male, but manufacturers have seem to have woken up to the fact that half of the population has a female body and are factoring this into their seat designs and safety features (Mazda and Volvo, for example).  That’s a topic for another day (and one I’ve discussed before) but in the meantime, if you aim to have a neutral spine and to keep a gentle bend in your arms and your legs while driving, you should be about right.

And don’t forget to allow for regular breaks to get up out of your seat during a longer journey.

One Thing They Don’t Tell You About EVs When The Rubber Meets The Road

The thing that a few of the proponents of EVs don’t often tell you about is about the tyres.  They’ll tell you about how EVs produce less in the tailpipe emissions department and about how quiet they are and how much better the range is these days, but if you’re new to the world of electric vehicles, you may be in for a surprise the first time you have to change the tyres.

What they don’t tell you is that EVs need special tyres and fitting the sort of tyre that worked perfectly well for an ICE vehicle of the same size or even the same weight won’t work on an EV. The tyres on an EV have to cope with a number of the characteristics of electrical motors. Specifically, the tyres have to cope with the increased torque, the weight of the battery pack, the need for better energy efficiency and the need to reduce road noise.

Because electric motors behave differently from internal combustion engines, they have much higher torque figures. Torque, as we should remember from our high school physics class, is rotational force (as opposed to linear acceleration), so it bites in where the rubber hits the road – literally.  The more torque, the more force is applied.  Now, I like a good bit of torque in a motor, but tyres don’t like it as much, and too much can wear them out more quickly. This means that an EV has to have tougher tyres. They also have to have more grip to avoid slipping when accelerating, especially in wet or slippery conditions.

On top of that, the tyre has to handle the increased weight. You might not realise this, given that most EVs tend to be smaller urban vehicles (although this is changing).  However, EVs weight more because of the battery pack. In fact, the battery pack can make up to quarter of the weight of an EV – and yes, this outweighs the bits that aren’t in an EV, such as the radiator, the fuel tank, the exhaust system and so forth. The battery pack also needs to be protected against mechanical damage (such damage is very bad news for the battery and is the leading cause of electrical car fires). This extra weight applies to hybrids as well as to purely electric vehicles (battery electric vehicles or BEVs). This means that the sidewalls on the tyres for EVs need to be stronger and heavier to carry the weight.

These two factors alone would be enough to indicate that putting regular tyres on an EV or hybrid vehicle is a bad idea, as the tyres would wear out more quickly – a lot more quickly! In fact, some have argued that if you are concerned about the environment, you should bear in mind that although EVs produce less from the tailpipe, they create more particulate matter from tyre wear. This is why several of the big-name tyre manufacturers have created special tyres for EVs.

If you’ve ever looked at the tyres made specifically for EVs, you may notice that they are taller and thinner. This is to decrease the rolling resistance.  Going back to high school physics once more, something that’s heavier has more inertia and thus requires more force to get moving (think about how easy it is to kick a soccer ball rather than a medicine ball).  Naturally, a tyre that’s stronger and more resistant to wear will be heavier, which would mean more inertia and thus rolling resistance. Making the tyre narrower will reduce the drag and thus the rolling resistance. This is important, because if you have waited half an hour to charge up your EV from a public charging station, you want that charge to last as long as possible before you have to do it again, so reducing the drag and the rolling resistance will be more energy efficient.

Lastly, there’s the noise issue. In an ICE vehicle, the rumble of the engine drowns out the road noise.  In an EV, there is no rumble, so road noise is the only thing you can hear.  Road noise isn’t quite as soothing as engine noise (most of the time), and that’s the only thing that you can hear in an EV, especially if you’ve switched off the sound system to save power and extend the battery range.

You can put tyres designed for other cars on EVs and hybrids, but three things need to be borne in mind.  Firstly, you have to be sure to get something that can handle the extra weight.  Secondly, a regular tyre will reduce the range of the battery.  Thirdly, the tyre will wear out a lot more quickly, meaning that you won’t actually save anything by putting regular bog-standard tyres on an EV. 

It’s best to put the proper tyres on an EV, as you will get better range and longer tyre life out of them.  Admittedly, these tyres are more expensive (like performance tyres on a splashy sports car).  They will also wear out more quickly, but not quite as quickly.  This is something that tyre manufacturers such as Michelin are working on but you will have to factor in if when deciding if an EV is right for you and your budget.  Despite being built tougher, these tyres still need to be maintained correctly – checking the pressure and rotating them regularly.

As with all things, the issue of battery weight and tyre wear are things that researchers are looking into and trying to improve, so we can look for things to get better (and hopefully cheaper) as time passes.

Extending The Life Of EV Batteries

One of the big questions that a lot of people have about making the shift from ICE (internal combustion engine) vehicles to EVs of any sort is the issue of battery life.  In this context, battery life doesn’t refer to how many kilometres the batteries will take you (this is technically known as battery range) but the actual lifespan of the battery unit itself.  If you’ve had any experience with any kind of rechargeable battery – which most of us have had – then you’ll know that even though you can recharge a battery a certain number of times, you can’t do it forever and eventually the battery will die, never to be recharged again.

Having said that, the lifespan of EV batteries is pretty good. In fact, the manufacturers claim that batteries can last for about 10–12 years, which is longer than the average lifespan of a whole car in some countries (although those who like second-hand cars or who are into classic cars may raise an eyebrow at this statistic). They’ve also got warranties to ensure that they last for a certain amount of time.

However, people researching rechargeable batteries don’t tend to measure the lifespan of batteries in terms of time (partly because no scientist in a rapidly developing field wants to spend 10 years running an experiment). Instead, they measure the lifespan of a rechargeable battery in charge–discharge cycles. To understand why they do this, we need to understand a bit about the science of a rechargeable battery.  Don’t panic – I won’t get into too much detail, partly because I don’t have a PhD in it and can’t wrap my head fully around some of the minute details.

In any battery, an electrical current is generated when ions (particle with an electrical charge) move from the negatively charged anode through an electrolyte to the positively charged cathode. This keeps going until everything balances out and the electrochemical reaction stops.  You can do this yourself with a copper coin (if you can find one these days), a zinc-coated nail and a lemon. Attach a wire to the coin and the nail, maybe connecting fairy lights in the middle, stick them in a lemon and watch the lights glow. However, in a rechargeable battery, this processed can be reversed, shuttling those ions back to the anode again.

In a rechargeable battery, every time the reaction comes to an end, i.e., complete discharge, that’s considered to be a full cycle.  In the lab, to test a battery’s lifespan, researchers charge and drain and charge and drain and… until the material in the anode and/or cathode starts to deteriorate, which all things do over time.  They also measure capacity decay. Over time, any rechargeable battery will lose the amount of charge it can store. Again, this is related to the number of charge–discharge cycles.

So what does that mean for EV batteries?  Although the manufacturers measure lifespan in years, this figure is based the ideal battery user.  If you charge your battery the right way and use it in the right way, then you’ll get the maximum lifespan from your EV’s battery pack. However, if you don’t, you’ll shorten the lifespan of the battery.

You can imagine the number of charge–discharge cycles in a battery as kind of like lives in a computer game.  You’ve got a lot of them, but every time, you get those hit points down to zero and have to “respawn”, you’ve used up another life.  However, unlike a computer game character’s life, hitting either extreme (full charge as well as full discharge) will shorten the lifespan because it puts stress on the battery – kind of like keeping a bow fully strung and at full draw most of the time, which, as any archer will tell you, isn’t good for the bow.

This means that ideally, you should avoid hitting these extremes.  This means that exhausting your battery’s charge completely is a bad idea.  However, so is topping it up to 100% all the time.

At this point, those of you who are familiar with rechargeable NiCad batteries will be scratching your heads because you’ve heard of “battery memory”.  NiCad rechargeables (these are the sort that you buy to put in things that come with the label Batteries Not Included) do have a “memory”, meaning that if you are in the habit of recharging the batteries when they hit 10% charge, they’ll start acting as though 10% is the new zero.  However, lithium ion batteries don’t have a battery memory effect, meaning that you won’t reduce their charging capacity if you top up the battery’s charge when it dips below a certain level.

In fact, what manufacturers recommend for preserving the life of a battery sounds rather like the principles used for managing blood sugar in Type 1 (insulin-dependent) diabetes.  You don’t want things to drop too low, but you don’t want them to go too high, either.  The ideal is to keep batteries between 80% charge (which is why the charging times given by EV manufacturers are usually the time taken to reach 80% charge) and either 20% or 40% charge. On top of that, rapid charges and rapid discharges also stress the battery.

In practice, this means the following:

• Don’t recharge your EV to overnight every night. However, you need to balance this against what you know about how and where you’ll be driving and where the accessible chargers are.
• Don’t let the battery drain too quickly. This means that you have to be very careful when it comes to things like towing, going uphill and running too many things that require electricity at once.  In other words, if it’s a freezing cold rainy night when having the lights, wipers and heaters going is a must, then you have to decide if it’s really worth it to use the sound system as well.
• Although DC rapid charging is convenient, it does stress the battery, so reserve this for when you absolutely have to.  DC rapid charging isn’t catastrophic for your EV’s battery and you can do it now and then without putting a serious dent in your lifespan, but it does put a bit more stress on it than slower AC charging, so don’t do it all the time.
• Extreme temperatures make the lithium in the batteries do funny things.  Getting too hot is the most dramatic, but most modern battery packs (thank goodness!) have cooling systems to ensure that they don’t overheat (these systems use the battery’s own charge to operate).  Getting too cold is also a problem, as the electrochemical reaction producing the charge is slowed right down, which translates to reduced range and slower charging times. Some battery packs, notably in Tesla vehicles, have systems that keep them at the ideal temperature – though at the cost of range. However, these can drain the battery more quickly, which shortens the lifespan.
• If your EV has to go into long-term storage, keep it on a trickle charger or a smart charger to ensure that it stays about half charged.