[carthick1000]

Recently the Dutch EV startup Lightyear published a blogpost about the factors affecting the real world range of EV's. Though most of the things are widely known in the EV community, it will provide a good overview for non-EV drivers.

A very short comparison between a regular car and electric one is that a petrol powered car burns fuel to produce energy, while an electric car carries around its energy in a battery. But the different way in which an electric car stores and recharges on electricity means that it carries comparatively less energy with it. This makes one metric particularly important to an electric car enthusiast, and that is efficiency.

Basically, the more efficient an electric vehicle is, the further it can drive, on the same amount of energy. Greater efficiency, greater range.

So what affects an electric vehicle’s range?

Lightyear One energy consumption for 3 drive cycles:



Temperature
Unlike its fossil fuel counterpart, an electric vehicle transforms nearly all of its energy into motion. Although this makes electric vehicles more efficient overall, it can also lead to some decreases in range during winter. This happens because only 40% of the fuel that enters an internal combustion engine serves to turn the car’s wheels. The rest produces heat. Although this can be considered a waste during summer, it can’t be more perfect for wintertime. During the cold months, this heat can be reused to warm the car and its passengers without increasing fuel consumption.

On the other hand, an electric vehicle is too efficient to produce heat ‘accidentally’. Instead, it has to warm the driver and the compartment using energy that could have otherwise been used for driving. This means that an electric vehicle's range will see a decrease when driving in the cold, because the energy from the battery needs to be used for something other than driving. And we don’t know about you, but with Lightyear One, we like to keep our passengers as cozy and as warm as possible.

Rolling Resistance
At low speeds, the main source of energy consumption is rolling resistance, which is the friction between the tyres and the road. The heavier the car, the greater the friction. This becomes a problem when electric vehicles have to carry heavy batteries: the bigger the battery, the more battery you need to drive around for significant ranges. The Importance of lightweight materials in electric vehicles



Another element that can increase rolling resistance is temperature: the colder it is, the stiffer the rubber in the tyres becomes, decreasing its performance. To prevent any problem that might arise from rolling resistance, Lightyear One goes through a lightweight cycle. The main goal of it is to make the car lighter, starting with lighter motors. We accomplish weight reduction all across the board, and, by making one part of the car lighter, we can make the rest lighter, as well, all leading to increased efficiency.

And yes, this is the core of Lightyear’s approach: we reach exceptional ranges through efficiency rather than a big battery.

Wind Resistance
At high speeds, wind resistance is even more important than rolling resistance. The faster a car moves, the more air it has to move through, and the more energy it wastes fighting against the wind. In winter, when the air is colder, it becomes denser, so wind resistance increases, affecting the car’s range even further. That is why a focus on aerodynamics is essential to maximising an electric vehicle’s range.

The solutions we came up with for Lightyear One are replacing the side mirrors with smaller side cameras, an elongated shape, and a streamlined design. We also moved the motors in the wheels, which cut the requirement for a transmission system, which, at the end, smoothened the underbelly. Because Lightyear One isn’t just a car, but a statement and a showmanship of amazing engineering. All these aspects reduce the wind resistance, giving Lightyear One a record breaking aerodynamic coefficient and increasing the car’s range at high speeds.



Of course, the range of your electric vehicle is dependent on environmental factors and the way you drive, but by maximising efficiency all across the board, we can help you reach exceptional ranges, no matter how cold it is or how fast you drive.

So, instead of explosive acceleration and the biggest battery pack, isn’t it simpler to trim down on the unnecessary, and just opt for the car that will bring you the furthest?

source

[GTO]

From the point-of-view of the "idiot" behind the wheel

- Aggressive driving truly kills an EV's range. It's more like a turbo-petrol in that sense, rather than a turbo-diesel which still gives good FE with a heavy foot. EVs are very sensitive to throttle input.

- Consumption of onboard electronics, including the air-conditioner, headlights etc.

- Surprisingly, EVs give either the same FE in the city compared to the highway, or better FE in the city. No regen braking, but there are more reasons. This is unlike ICE engines which will give you 50 - 100% more fuel efficiency on the highway. Of course, that could change with 2-gear EVs which have a taller ratio for the highway (e.g. Taycan).

- Tesla batteries are aging well, but they are pretty much the gold standard. I expect the cheaper batteries of mass-market EVs to deteriorate faster than Tesla's high-end no-expense-spared batteries.

Also linking to my must-read thread on EVs (Electric Cars...through the eyes of a diehard petrol-head).

[V.Narayan]

Thank you carthick1000 for this most apt thread. Apt for the times that are coming.

As GTO put it EVs will not give us lower range (or FE if you might) in city driving which is such a boon for most of us most of the time. Also, I expect, in the near future (3 to 4 years) we will see cars made more of the newer lighter materials - carbonfibre, new lighter aluminium alloys because every kilo saved in body weight will translate to either greater range directly or to increased battery carrying capacity. The second area I expect technology to clutch in, albeit over a slightly lioner time frame, is in rolling resistance - literally the rubber meets the road bit.

One possible positive outcome, fingers and toes crossed, is that speeding & rash driving at least within city limits might get dampened by car and two-wheelers as gradually (hopefully) everyone will get more aware and concerned about range. In India that is a hope.

[gkveda]

Simple electrical engineering basics tell us more current outflow leads to more battery drain.

1. More speed requires more current. So battery drains fast. This has two effects. One, more drain due to motor speed combined with wind resistance that adds to increased load. So more current to overcome wind resistance.
2. More gizmos - more current consumption.
3. More accessories - more leakage current
4. Fatter tires - more resistance to move leading to more current consumption
5. More turns on the road(ghat sections) draws more current to drive steering motor and indicator lights, (These things count because, there is no alternator to recharge the battery as in case of ICE Cars)

[flanker]

Originally Posted by GTO

Tesla batteries are aging well, but they are pretty much the gold standard. I expect the cheaper batteries of mass-market EVs to deteriorate faster than Tesla's high-end no-expense-spared batteries.

I wouldn't say that Tesla batteries are better. They have been using 18650 and 2170 cylindrical cells (Panasonic manufactured or in collaboration). 18650 was readily available and cylindrical cells are easier/cheaper to produce. Cylindrical are also most efficient in terms of volume. The downside is the higher internal resistance and thermal properties. The design to cool the cells from the side isn't the best but given the tab connecting the terminal is a thermal bottleneck there isn't any other way. Tesla's new 4860 tabless cell solves these two problems. It offers much lower internal resistance in a cylindrical package and will allow for more efficient cooling system from the bottom of the cell.

Most other EV manufacturers have tended towards prismatic cells. These are more difficult/expensive to produce but don't have the resistance and thermal issues of conventional cylindrical cells.

Some EVs like Leaf have shown worse life not because of cell technology but because of relying on passive cooling of the packs.

As for LFP(lithium iron phosphate) chemistry, only few companies have the technology. Tesla Model 3 LFP uses cells manufactured by CATL. CATL also makes the battery packs for all MG EVs.

[TrackDay]

I guess proper planning might also be a factor. For instance before setting out on a journey, should I do it during the day or night ? Night driving means consumption of energy for mainly the lights, where day time driving could cause the A/C to draw more power due to the daytime heat.

Another factor could be to keep phones charged before a journey rather than charge it in the car.

Keeping cars clean could also turn out to be an important criteria. Junk inside the car and boot can easily add on weight to the car. Similarly dirt and muck on the car exterior and underbody could be addon in weight.

[Kosfactor]

As we all know weight is the enemy of things that move. Somehow we need to invent a light weight battery that is cheap to make as well as fast to charge. Imagine an EV pack that bolts into the engine bay and fuel tank space of a Baleno, gives the same performance and range, as well as charges in a few minutes. It would be nice to have.

I`m wondering why in the last few hundred years we have not seen such a battery.

As our country is adding more and more expressways to aid economic progress, we need vehicles that are fast as well. Reach places faster, do more things and get back home just as fast.

Right now we can fill up in 5 minutes, have a tank range of 700 Kms while maintaining 100+ speeds in the comfort of AC and all other accessories. New technology (if at all it is) should be better, no compromise whatsoever.

[DarthVeda]

Originally Posted by GTO

- Consumption of onboard electronics, including the air-conditioner, headlights etc.

The impact of AC is overblown on the range, we are looking at reduction of 10 to 20km on a journey of 200km, something that we can live with if the outside is resembling oven. I would not worry about electronics, headlights as they are too miniscule to the scheme of things.

- Surprisingly, EVs give either the same FE in the city compared to the highway, or better FE in the city. No regen braking, but there are more reasons. This is unlike ICE engines which will give you 50 - 100% more fuel efficiency on the highway. Of course, that could change with 2-gear EVs which have a taller ratio for the highway (e.g. Taycan).

In other words, FE of EV is dependent on speed, acceleration/deceleration patterns. Please don't use the word "regen is absent" in highway for less efficiency like this journalists tend to use. The reason highway efficiency is low is because you are on constant speed of 80 and above. Go at 40 to 50kmph on highway and you will see insane efficiency. Regen only recuperates lost energy (30% of it or so), it does not generate electricity out of nowhere. The best way to utilize energy is to not lose it at all, i.e, coast on highway as much as possible, minimize hard braking etc.
[/quote]

[SKC-auto]

Originally Posted by TrackDay

.
Another factor could be to keep phones charged before a journey rather than charge it in the car.

Actually you can charge couple of phones, laptops and cameras without any worry. For every 1km you can charge 6 phones or 4 laptops.

The only care you should take to increase the mileage is avoid hilly terrain, drive slow for aerodynamic reasons and use brakes by anticipating traffic.

IIRC, the aerodynamic drag increases exponentially, 70kmph is far better than 80kmph which is far better than 90kmph.

Phone 24wh battery is 1/1250th of Nexon battery
Laptop 40wh battery is 1/750th of Nexon battery

[flanker]

Everything adds up, specially when you are trying to maximise the comfortable /usable range on a long trip.

For example, for MG ZS EV just the side lights and headlights are 160w. Which amounts to 1KWH in 6 hours night drive. Equivalent to about 8 to 10 km depending on other conditions and driving style.

I have swapped out most of the halogens to Osram LEDs cutting about 100w. This might not be much, but as range is already limited every 5 to 10 kilometers can make the difference in making the fast charger or destination charger comfortably.

[carthick1000]

Originally Posted by flanker

For example, for MG ZS EV just the side lights and headlights are 160w. Which amounts to 1KWH in 6 hours night drive. Equivalent to about 8 to 10 km depending on other conditions and driving style.

I have swapped out most of the halogens to Osram LEDs cutting about 100w.

Good to know that MG ZS EV chose to use Halogens in an electric car. Either they must be thinking ease of replacement or too confident about the range of their battery pack. But it is pretty good that you chose to replace with LEDS. Smart .

[flanker]

Originally Posted by carthick1000

Good to know that MG ZS EV chose to use Halogens in an electric car. Either they must be thinking ease of replacement or too confident about the range of their battery pack.

Yes, besides just the headlamps, the sidelight cluster has 3 halogens per side, making 6 in total. And 2 for the number plate. It is beyond me why they would use halogens in an EV.

Nexon EV also has halogen headlamps. Not sure about taillight cluster and how many halogens for sidelights.

At least both the cars get projectors and any half decent LED should produce a glare free pattern

[shaheenazk]

Originally Posted by gkveda

(These things count because, there is no alternator to recharge the battery as in case of ICE Cars)

This got me thinking that why there is no alternator in the EVs to recharge the batteries on the go? Or perhaps a dynamo on each wheel will do the trick? This should help in getting more range. Pardon me if my suggestion sounds silly.

[carthick1000]

Originally Posted by shaheenazk

This got me thinking that why there is no alternator in the EVs to recharge the batteries on the go? Or perhaps a dynamo on each wheel will do the trick? This should help in getting more range. Pardon me if my suggestion sounds silly.

No question or suggestion is silly.



An EV does not have an engine. As you see in the pic above, an Alternator is driven by an engine, more precisely by the crank pulley. So mechanical energy produced by rotation of engine is converted to electricity by an Alternator. It is not very efficient.

EVs use a much better and efficient solution for this. EVs use DC-DC converter to convert 400V DC(or sometimes 800V DC) from the main battery pack to 12V DC used by normal 12V equipment on the car. I suggest you this link, if you want to know in detail why an alternator is not used in EVs.

For your suggestion about Dynamos in each wheel, you don't need this in an EV as the Electric motors driving your wheel double up as alternators and regenerate energy while braking or if you release the accelerator pedal. An old article from Tesla explains this in a crisp way.

[Holyghost]

Originally Posted by flanker

As for LFP(lithium iron phosphate) chemistry, only few companies have the technology. Tesla Model 3 LFP uses cells manufactured by CATL. CATL also makes the battery packs for all MG EVs.

I think it would be more apt to say "only few companies still manufactures LFPs". LFP is one of the oldest Li battery technology and most companies moved over to other Li-Ion chemistries except a few in China. Remember the older Reva cars (Predecessor of E2O) used LFP batteries when they switched from Lead Acid to Li-Ion.

The cost and availability of Nickel/Cobalt and battery longevity/safety for EVs has brought LFPs back to mainstream since these are the type of Li-Ions that do not catch fire and can also be recharged upwards of 3000 cycles.
LFPs are still a very inefficient battery when it comes to Volumetric and Gravimetric energy densities. But for low range EVs, LFPs are still a good choice as they do not have to worry about the weight and size of the batteries. Both my E2O and Nexon EV uses LFP batteries.