Speak EV - Electric Car Forums banner

1 - 20 of 66 Posts

·
Registered
Joined
·
2 Posts
Discussion Starter #1
I received my first electric car a kia e nero in May and my average fuel consumption for the first 5000 miles is 4.1 miles per kWh. With motorway driving I could achieve almost 4.0 miles per kWh at 70 mph. In recent weeks this has fallen to about 3.6 at 70 mph and this is reducing my range to about 230 miles. Anyone else having a similar experience?
 

·
Zoe Devotee
Joined
·
7,634 Posts
Welcome to the world Of EV ownership. Rubbish range as soon as it turns cooler.
 

·
Registered
Joined
·
131 Posts
Range is always going to be lower in the colder months. More energy going to battery and cabin heating. Air is thicker. Damp roads. Etc.

However, 3.6 mpkWh at 70mph in an e-Niro sounds about right anyway. Only the Ioniq and the Model 3 with aero wheels are going to see 4+ at that speed
 

·
Registered
Joined
·
2,552 Posts
I think putting fuel in it probably isn’t helping ;)

but yes

I can get 180 (best case) in summer and 120 (worst case) in winter

this should have been something you picked up on through your research before buying.

how many miles per day are you doing? More that 200?

JJ
 

·
Registered
Joined
·
2 Posts
Discussion Starter #6
I waited for a bigger battery (64kWh) model to come out before purchasing my ev. In the 5 months I have had the car I have never had to use a charging station on the journey. My longest journey has been 215 miles. The car is still meeting my expectation even in the colder weather. There is very little information out there for new ev drivers hence my post to discover if my reduction in range is the norm.
 

·
Evezy £50 code - cada7
Joined
·
147 Posts
I waited for a bigger battery (64kWh) model to come out before purchasing my ev. In the 5 months I have had the car I have never had to use a charging station on the journey. My longest journey has been 215 miles. The car is still meeting my expectation even in the colder weather. There is very little information out there for new ev drivers hence my post to discover if my reduction in range is the norm.
I'd hope you did some research and learned about things like that before spending a lot of money on an EV. It's a bit risky if you didn't, but with the fact that you got something with such a big battery and pretty good efficiency I guess you got lucky that it's not caused you any troubles.

When you get into deep winter and you have snow and ice, sub zero temperatures you'll find the range significantly lower, and if you do need to plug in along your route at that point you're looking at slower charging speeds too. Unfortunately this is the case with all EVs.

On a motorway, maybe just slow down a little bit? The difference between 60 and 70 in an EV is pretty big with how it affects your range, and on most journeys the time difference really isn't noticeable. Especially if its the difference between needing to stop to charge and making it with your existing battery level, you'll probably actually end up completing the journey a little faster by slowing down. Sit a safe distance behind a lorry doing a steady speed and not only will you get the benefits noted above, but you'll also end up having so much air pushed out the way by the vehicle in front your efficiency will further rise as a result too.
 

·
Registered
Joined
·
123 Posts
Can any of the sparks, or physicists, on the forum quantify what percentage of the difference is typically thicker air etc that would affect all cars, what is the effect of the battery being charged while cold, and what (if any) is due to the battery being colder as the electricity is used?

I did once ask a rocket scientist (really...) about it, and he couldn’t come up with an answer on the spot.
 

·
Registered
Joined
·
821 Posts
As long as you leave home fully charged and have to stop say after 60+ miles driving at 60 miles plus then the battery should be warm enough to
charge on a rapid on route very quickly.
Its when you get up on a cold morning and find out that you forgot to plugin overnight, and then you decide to go to nearest Rapid that is only 5 miles away ,only to find charging on it is pretty slow.

Batteries like warm weather :)
 

·
Registered
Joined
·
893 Posts
Temperature causes a proportional change in air resistance, so if temp at 0c 273K increases to 20c 293K, there is a 293/273 or about 7% variation in air resistance. As speed is a squared factor, reducing speed from 70mph to 67mph gives a 7% reduction in air resistance. I find that AC is worse than modest heating.

Battery chemistry factors are less clear in maths.
 

·
Registered
Joined
·
319 Posts
I received my first electric car a kia e nero in May and my average fuel consumption for the first 5000 miles is 4.1 miles per kWh. With motorway driving I could achieve almost 4.0 miles per kWh at 70 mph. In recent weeks this has fallen to about 3.6 at 70 mph and this is reducing my range to about 230 miles. Anyone else having a similar experience?
I have had my e-Niro for just over a month now and travelled mainly on motorways at 70 mph. In the current cooler weather I average 3.8 /3.9. I do however use fast / rapid chargers as well as my own home charger. I have travelled about 2200 miles. I use the cruise control a lot of the time. The best economy I have had is 5.1 and the worst 3.8. It is a great car and there are not many competitors in terms of range for the price. I am expecting the range to reduce as the winter weather approaches.
 

·
Registered
Joined
·
2,191 Posts
Here are a few UK realistic numbers to illustrate the affect of lower air temperatures on the power required to push a vehicle through still air:-

Air temp 20C dry bulb 70%RH 1.1860kg/ m3, 8C 85% 1.2455, -2C 85% 1.2974


Using 20C numbers as base, air density had increased by 5% at 8C and 9% by -2C.

As aerodynamic drag is proportional to air density, the power required to overcome this drag will be higher by the same proportion at all speeds for all vehicles.
 

·
I'm not crazy, the attack has begun.
Joined
·
23,090 Posts
The same thing happens with ICE cars, but no-one really notices.
Unsupported fake news.

Show me some evidence of this.

Yes there is an efficiency penalty in the first few miles as the engine block heats through, so if you are looking at short trip efficiencies it's true if not more so for ICE. A trip average will show lower in winter due to the warm-up process dragging the net average down, so by how much will depend on the length of the total averaged journey efficiency. But if you reset your computer after the warm up phase it'd return undetectably different numbers as in summer.

But once the block is heated through there is actually an improvement for ICE because;
-the thermal sink is lower temperature which improves the thermodynamic efficiency of the engine
-the charge density of air is higher, so it can put out more power for lower revs (less swept distance = less frictional losses)
-the injected fuel is cooler and improves charge injection and mixing
 

·
Registered
Joined
·
673 Posts
I used to keep a close check on my MPG in my last petrol car. Over the winter month's my MPG was measurably lower, roughly 46mpg in Summer and 42mpg in Winter. Short trips with a cold block are normal for winter drivers, having to idle for a bit longer to get enough heat through to de-mist the screen. Not heating the cabin to keep the screen clear for the first few miles were normal for me. The wind resistance, stiffer tyres, & more rain all have an effect.

With EV's I think the biggest loss is the reduced capacity of a cold battery, when you do a long trip, the battery is toasty when it's charged and the range improves. On cold days I've generally found 10% of battery power is used for heating with a heat pump heater. I don't usually bother to pre-heat the car which would of course reduce that 10% a bit.

It's worth making your screen wash a bit stronger in an EV, I had the pipes freeze in the bonnet in a particularly cold period a couple of years ago and with so little heat generated by the electronics and motor they only thawed out when the temperature went back up.
 

·
Registered
Joined
·
1,000 Posts
@donald So you are trying to tell me that ICE cars move through different air density? The cars somehow warp the space-time continuum around them and are no longer subjected to the same drag due to colder air?

How about running the heating? Pump, HVAC, etc...

My experience on a regular 150miles trip is similar to @Big277wave, diesel car in summer would manage above 50 mpg and generally in winter will be below 50.

Edit PS: Just to demonstrate how much spare time I have had and geekiness, I have observed that just driving during the night and the day, gives a difference of ~2mpg in favour of the day.
 

·
Registered
Joined
·
1,443 Posts
How about running the heating? Pump, HVAC, etc...
That's where ICE cars are better. In winter there is no penalty for using heat - the hot water is there as a waste product, once warmed up, the pump is always on anyway and it no longer has to drive the aircon compressor.
EVs have to use useful traction power to provide the heat.
 

·
I'm not crazy, the attack has begun.
Joined
·
23,090 Posts
@donald So you are trying to tell me that ICE cars move through different air density? The cars somehow warp the space-time continuum around them and are no longer subjected to the same drag due to colder air?
Did I say that? I think not.

Air density is a negative impact for sure, which roughly balances out the efficiency gains of operating an ICE with a colder sink.

That's why I did not say it was 'better', but 'measurably no different'.

How about running the heating? Pump, HVAC, etc...
Obviously, an EV suffers badly with that in winter and an ICE gets 'free' heating.

In summer, the ICE will need to use power to run the AC, hence that is another relative benefit to ICE in winter which also mitigates the air density increase.

There are also wetter roads, which sap all cars, again not hugely noticed by ICE because they are not at the limits of operating efficiency.

My experience on a regular 150miles trip is similar to @Big277wave, diesel car in summer would manage above 50 mpg and generally in winter will be below 50.
50.1mpg to 49.9mpg doesn't sound that big a difference? Do you want to be more precise to help clarify an assessment of that comment?
 

·
Registered
Joined
·
42 Posts
The average commute is 16 miles. Therefore for the majority, the cold weather will have a measurable effect on ICE mpg. I changed from ICE because of my short commutes. Over the winter I saw a drop of 15% in mpg.
 

·
Registered
Joined
·
1,000 Posts
50.1mpg to 49.9mpg doesn't sound that big a difference? Do you want to be more precise to help clarify an assessment of that comment?
If you really really want, winter efficiency was 47 to 49mpg. Summer was 52 to 54mpg. That is seat leon, 1.6tdi with a 6speed DSG. 150 miles one way generally using 70mph cruise. Average speed ~ 58mph plus or minus 2. Data collected across 3 years and ~30 journeys.

And I never said heat generation, I said running a pump through the HVAC to deliver heating. That includes fans generally running harder than in the summer.
 
1 - 20 of 66 Posts
Top