Electric Vehicles: What have you spotted?

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Mandrake
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Re: Electric Vehicles: What have you spotted?

Post by Mandrake »

white exec wrote:
19 Oct 2018, 08:14
Electric buses and warmth
Came across some articles on this issue last week, looking at how to keep all-electric battery bus interiors acceptably warm (or cooled).

What was interesting was that the driving range (155mi_250km/day+) was not an issue with currently available vehicles, but heating remained so. A whole variety of solutions on offer (from old friends like Valeo and Webasto, amongst others). Interesting figure: using the traction batteries for interior heating would require an additional 2000kg of batteries to be carried.

http://www.eliptic-project.eu/news/are- ... sion-buses
https://www.busworld.org/uploads/exhibi ... -buses.pdf
After driving ICE vehicles all your life it's easy to take for granted that heating a car is "free" and has no effect on range or MPG. But it's only free in the sense that the car is throwing away 80% of the energy in the fuel as waste heat into the environment year round even when you don't want heating, and in the winter you can capture say 10% of that to warm the interior and then still throw the other 70% away. :lol:

So it's free if you don't mind throwing away 70-80% of the fuel you buy year round... :twisted: The efficiency of an electric drivetrain is so high (90% is typical including battery, inverter and motor) that there isn't enough waste heat to heat the interior any significant amount - no EV that I'm aware of tries to use drive train or battery heat to heat the cabin, although a few will use the drivetrain waste heat to warm the battery in cold weather to bring the battery up to more efficient temperature.

So you end up having to use your precious traction battery energy to run the heater as well, and this can reduce range by anywhere from about 10% to 30% depending on heater system design. On the plus side, in the summer when you don't need heating there is no additional waste heat being pumped out, so your summer driving is as efficient as it could be.

A surprising number of EV's still just use resistive heaters - which fall into two broad categories. PTC water heater or fan heater.

My Ion uses the old fashioned PTC water heater approach using a conventional heater matrix. This is probably because it's based on a petrol car that was originally designed with a heater matrix. Instead of completely redesigning the heating and cooling system they essentially fitted a 5kW 360 volt PTC water heater which heats a glycol coolant loop that is pumped around the heater matrix and PTC heater. Maximum temperature is about 60 degrees so the coolant loop is not pressurised and it doesn't do anything else other than the heater. (There is a separate coolant loop for the motor and drive inverter which goes through the radiator at the front)

Simple, very reliable and safe, and it works, but very slow to respond as you have a huge thermal mass of the PTC heater, a loop of coolant and the heater matrix itself. So the heater takes a good 5 minutes to fully heat up in the morning (although that's still quicker than an idling ICE first thing in the morning) and is very slow to respond to increases or decreases of the temperature knob - which can take several minutes from when you turn the temperature up or down until you notice a significant change.

There is probably some efficiency loss in having to heat the thermal mass of everything up, because when you get to your destination and leave the car there is still a large thermal mass sitting there hot wasting that stored energy. If you turn the heater off earlier before reaching your destination it stops the coolant pump so you still can't extract the latent heat from the PTC unit. Definitely not my choice of heater.

Some EV's use what is essentially identical to a mains operated fan heater, where you have coils of nichrome wire running directly from the ~360v traction battery heating the airflow as it goes through the ducts. The advantages of this system are super fast response time, (turn the heater on and it is hot in seconds, so you could have your window thawed out in the morning in minutes with no engine running) and very low thermal mass. (not much latent heat loss after turning the heater off and leaving the car)

The disadvantage is probably in making this safe - for safety reasons you'd have to be very careful about bringing the high voltage for the heater element into the cabin, most likely the heater box is located in the "engine bay" to avoid bringing high voltage into the cabin. You do also rely a lot on your pollen filter - the last thing you want is bugs, dirt, dust etc getting into your high voltage element causing shorts, catching on fire etc... Likewise water from a leaking scuttle getting into it would not be good. :shock: Another possible problem might be burnt dust smell that you get on some fan heaters that have sat unused for a long time.

The third approach is to use a heat pump, which can increase the coefficient of performance by up to about 3 - so you can get the same cabin heat from 1kW that a resistance heater would need 3kW for. A heat pump can bring the range penalty in winter down from 25-30% to more like 10-15%. The disadvantage is heat pumps don't work well in very low temperatures (below about -10C) so still need a resistance heater to work in conjunction with it at very low temperatures. Not really a problem in the UK though, mainly an issue in places like Canada.

Heat pumps are just AC's running backwards of course so make a little bit of noise and do eventually wear out or break down whereas a PTC or fan heater style heater basically lasts forever.

Interestingly while new Leaf's, Hyundai Ioniq and Kona and many other EV's have heat pumps either as standard or as options, Tesla have decided to stick to fan heater style resistance heaters. Not entirely sure why, but it means that a Tesla will lose more range as a percentage in winter than an EV with a heat pump.

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white exec
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Re: Electric Vehicles: What have you spotted?

Post by white exec »

Lots of interesting detail there, Simon.
Ironic that a stumbling block for a good EV is not traction, but keeping the passengers warm!

One thing you didn't mention was 'pre-warming' on a cold morning, before the journey begins. Buses are doing this (depot mains), I wonder whether and e-cars are? There seems to be an advantage not in just stepping into a warm and de-misted/de-iced car, but also having its interior structure warm, so a smaller heating unit (or less power) can be used en route.

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Re: Electric Vehicles: What have you spotted?

Post by Mandrake »

Good point. Most EV's do support pre-heating while plugged in.

So you plug your car in to charge over night then either manually (in the car or via a smartphone app) or on a timer turn the heater on a while before you're planning to leave in the morning and it will run the heater on full blast from mains power, thus not using up any range to initially heat the car. And of course no engine is running, only the blower fan and possibly a heat pump if the car has one.

So you go out to a silent, still locked, warm toasty car with all the ice melted off the windows ready to go. No scraping ice off windows, no temptation to drive off before it has warmed enough to avoid fogging with drivers breath and no idling engine to upset your neighbour.

Some EV's will let you remotely pre-heat even when not plugged in. That doesn't save any power of course but can save time - for example if you were leaving work it would be the difference between arriving at a freezing car covered in ice waiting for it to warm up enough to de-ice and drive it, and arriving at one that is already warmed up and de-iced so you can just get in and drive.

Sadly my Ion is too old and basic and can do none of the above! :( :lol: It won't let you run the heater while the car is plugged in, so my morning routine when there is ice on the window is to go out about an hour before leaving time, unplug it, use the second key to leave the car locked but turned on with the heater on full blast for about 10-15 minutes, then come back out, turn it back off and plug it back in. By the time I leave for work it is at 100% charge again and while it's cooled off a bit it will still be ice and fog free and warm up very quickly. (The PTC heater is still quite hot due to its thermal mass, so the heater warms up very quickly when setting off compared to if it had never been on and the PTC heater was starting at -4C...)

Pre-heating is a must have feature that I will make sure I get on the next EV I buy... :twisted:

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Re: Electric Vehicles: What have you spotted?

Post by Hell Razor5543 »

I don't know if this would help, but I have found that Rain-X seems to help on cold mornings. As water does not stick well to a treated windscreen neither does ice. I can normally brush any ice from the windscreen, as opposed to scraping it off.

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Re: Electric Vehicles: What have you spotted?

Post by Mandrake »

Hell Razor5543 wrote:
19 Oct 2018, 11:52
I don't know if this would help, but I have found that Rain-X seems to help on cold mornings. As water does not stick well to a treated windscreen neither does ice. I can normally brush any ice from the windscreen, as opposed to scraping it off.

I've never had much luck with RainX. Tried it, didn't like it...

I don't think I've ever had to scrape ice off the Ion - inches deep snow yes, but not ice. I just put the heater on full blast for about 10 minutes (and the rear demister) as described above and even in the coldest parts of last winter with a complete sheet of ice on the windscreen that was enough to fully deice all the windows in the car. On the Xantia I mainly used bottles of warm water over the windows as it took too long to wait for the heater to de-ice at idle as even after 15 minutes of idling the heater wouldn't be hot enough.

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Re: Electric Vehicles: What have you spotted?

Post by CitroJim »

You and your Rain-X James!!! How's your shares in the company that makes it doing? ;) :twisted: :lol:

I guess they must have gone down a bit recently if you're plugging it again!!!

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Re: Electric Vehicles: What have you spotted?

Post by Hell Razor5543 »

:D I don't have any shares in Rain-X; I just find that it meets my needs very well.

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Re: Electric Vehicles: What have you spotted?

Post by CitroJim »

Hell Razor5543 wrote:
19 Oct 2018, 14:32
:D I don't have any shares in Rain-X; I just find that it meets my needs very well.



Maybe you should James ;)

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Re: Electric Vehicles: What have you spotted?

Post by Peter.N. »

5 kw probably gives good heat but knocks about 15 miles of the range per hour, I know you are not going to need it on full all the time. The auxiliary heater in the 406 I think only runs at about 1 kw which is probably about all the alternator can supply but its quite good and heats up pretty quickly.

Peter

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Re: Electric Vehicles: What have you spotted?

Post by myglaren »

Lots of Leafs and Zoes today, and an Ionic.

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CitroJim
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Re: Electric Vehicles: What have you spotted?

Post by CitroJim »

The BBC ran this article today about the ban on petrol and diesel vehicles.

https://www.bbc.co.uk/news/uk-40726868

The car in the picture that accompanies the article... This one...
BBC News Website
BBC News Website
Looks to me a bit like an electric Saxo...

Is it?

Or is it my imagination?

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Re: Electric Vehicles: What have you spotted?

Post by Gibbo2286 »

Hang one of these in the car overnight, it worked in our outside lavvy. :)
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Re: Electric Vehicles: What have you spotted?

Post by CitroJim »

Gibbo2286 wrote:
19 Oct 2018, 18:26
Hang one of these in the car overnight, it worked in our outside lavvy. :)

Image


Indeed, I can remember my dad doing the same when I was a kid...

And having to break the rime of ice in the toilet bowl first-thing in the morning :lol:

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Re: Electric Vehicles: What have you spotted?

Post by Peter.N. »

I can remember when people put them alongside their cars at night - to save the battery. :)

Peter

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Re: Electric Vehicles: What have you spotted?

Post by Zelandeth »

CitroJim wrote:
19 Oct 2018, 18:20
The BBC ran this article today about the ban on petrol and diesel vehicles.

https://www.bbc.co.uk/news/uk-40726868

The car in the picture that accompanies the article... This one...

leccysaxo.jpg

Looks to me a bit like an electric Saxo...

Is it?

Or is it my imagination?

Image



Does indeed! Never seen an electric Saxo in person, but have done plenty of miles in an electric 106, so I'd assume they were out there at some point.

Really liked them...our ones at work solved the thorny issue of heating with a tiny petrol burner which heated a liquid loop and a standard heater matrix. The heater in them was absolutely epic, heated up in next to no time and got to levels of hot that only Lada's, Saabs and Volvos usually manage. Tank was a gallon and used to last several months of daily use...so the environmental impact of burning a little bit of petrol for heat can't have been too massive.

I have to admit that I'd really love to find one for local duties...but remember having a look a couple of years back and decent ones seemed to change hands for way more than I could justify.

One of our neighbours seems to have recently traded up from their Kia Optima to a Model S. Thought it was black originally until I saw it in direct sunlight today, it's actually a really deep pearlescent green. Tan leather and really dark wood trim, looks lovely. P100D spec, so the "full fat" version it seems.

Still want one...for all they do have their flaws and the styling being a love/hate thing...I just *like* them. I'd really like a chance to have a proper like around a Model X. Only had a very brief sit in one at the Detroit Auto Show a few years ago, but would like to have a better look at one. There's not a huge difference in size between it and the S, but I remember the feeling of space reminding me of the first time I climbed aboard a first generation Espace...so I'd really like a proper look.