Electric Car Experiences

[CJay]

Rental cars are cheap in the US. $30-40 a day, $200-300 for a week with unlimited miles. Auto insurance alone in most parts of the US will cost you $1000 a year per vehicle for liability coverage alone.

I’ve known non-EV owners who use rental cars for any long trips just because they don’t trust their cheap commuter vehicle.

Rentals can be as little as £12 a day here if you want a small car, I paid £17 a day with unlimited mileage for a Vauxhall Insignia (which I think is a Buick Regal in the US?) when I went to Scotland for a week.

I don't currently have a car so I'm looking at options and at the moment but an EV is working out to be the more expensive option even if I buy second hand.

[boffin]

So, it has no throttle, but reduces engine output by allowing less fuel/air charge into the cylinders.

Isn't that exactly how a throttle normally works?

Effectively, yes. The throttle (on a conventional gasoline engine) controls the amount of air that can enter the intake manifold. This in turn determines the amount of fuel injected into the air immediately prior to entering the cylinder.

Diesel engines on the other hand have no throttle, the power output is controlled by adjusting the amount of fuel injected directly into the combustion chamber.

It's still a throttle, it just meters fuel, not fuel+air.  Also some modern gasoline engines use gasoline direct injection, rather than pre-mixing air/fuel.  (Hydundai have a bunch of GDI engines)

[james_s]

While the term "throttle" is widely applied to any mechanism of regulating power output, technically the term most accurately describes the butterfly valve or other mechanism used to restrict airflow into the engine. As a verb to throttle is to choke or suffocate.

I'm aware of GDI engines, which is why I specifically mentioned "conventional" gasoline engines. GDI is an interesting technology, I'm somewhat surprised it was not more widespread sooner as it has been around for a long time. Many of the German aircraft engines from WWII were GDI, using mechanical injection pumps similar to older diesel engines.

[nctnico]

While the term "throttle" is widely applied to any mechanism of regulating power output, technically the term most accurately describes the butterfly valve or other mechanism used to restrict airflow into the engine. As a verb to throttle is to choke or suffocate.

I'm aware of GDI engines, which is why I specifically mentioned "conventional" gasoline engines. GDI is an interesting technology, I'm somewhat surprised it was not more widespread sooner as it has been around for a long time. Many of the German aircraft engines from WWII were GDI, using mechanical injection pumps similar to older diesel engines.

In general GDI engines have problems with sooth contamination in combination with exhaust recirculation. Mitsubishi can tell you all about their misfortunes when it comes to their GDI engines from the mid 90's. The primary problem is running the engines at low loads which shouldn't happen with the current downsized tubocharged engines.

See: https://www.honestjohn.co.uk/forum/post/index.htm?t=38913

[jmelson]

Interesting system, but yeah. Why do they use nimh in 2018 in the first place ? Why no lithium tech ?

Oh, they DON'T!  Mine is a 2009, they went to Li (something) in 2011, I think.  My daughter has an old Prius, which always had Li batteries, and hers is still going strong on the original battery.

Jon

[jmelson]

Isn't that exactly how a throttle normally works?

The throttle of an Otto-cycle engine puts a restriction in the intake manifold, and the engine has to work against that restriction to get air into the cylinders.  This is called "pumping loss" in the industry, and is a very significant loss of engine efficiency.  The Honda scheme allows the intake valve to stay open later, bridging from the intake stroke to the compression stroke, effectively shortening the intake stroke and the charge in the cylinder.  There is SOME loss there, as air passes the intake valve twice, but there is never any manifold vacuum, so at mid-throttle conditions, the pumping loss is reduced to a tiny amount.  This is a modified Atkinson cycle engine.

They also have a mode where they can shut all 16 valves while running in pure electric mode, and there is zero fuel consumption.  Due to the small size of the motor and battery, you can't drive very far like that - like 1/4 mile down a slight hill, maybe.

Jon

[free_electron]

I own two. I drive a Tesla Model-X 90D with all options and my wife has a Tesla Model-S 90D with most of the options.
I use autopilot on a daily basis to go to-from work. We both charge at home or at work.

For long trips : supercharger. We've done roadtrips to LA, Yosemite and other places. Last weekend we were in Lake County. charged the car fully the night before. Ran nonstop for 3 1/2 hours to Ukiah. Hooked it to the supercharger, went grocery shopping for 40 minutes and the battery was completely full again ( 240 miles ). Then we drove to Soda bay for a 4 day weekend. Drove around the area. plugged it in a regular 110 volt outlet during the night. That gives me about 40 miles in 10 hours. More than enough for the sightseeing and compensate for daily usage. On the way we stopped in Petaluma for lunch while hooked at the supercharger there. In 30 minuted the battery was topped off and we arrived home with 110 miles remaining.

I bought my first one almost 5 years ago Model-S 75. After driving that for almost 6 months i figured out : this is the future , and that is a company i want to work for. ( I was at ST Microelectronics at the time ). So i switched.
After my lease term was up i upgraded to a newer version Model-S. Last year i got married so my wife now drives the S and i got a model X.

I am writing this as a driver. Not as employee.

The only adaptation needed : a power outlet in the garage. As for daily driving : the battery is so large it is a non-issue.
For roadtrips : you can drive 3+ hours nonstop at highway speed. Then it is time for pipi and a starbucks anyway. Plug it in, visit restroom and grab a coffee and the thing is full.
Sure you can fill gasoline faster. But it is more fun to stretch the legs for 30 minutes. you arrive less tired at your destination.

Again : full disclosure : i work there , but i bought my first one before that. Am writing this purely as a driver of an EV. And no, there are no employee perks. All you get is free air in the tires.

[james_s]

Oh, they DON'T!  Mine is a 2009, they went to Li (something) in 2011, I think.  My daughter has an old Prius, which always had Li batteries, and hers is still going strong on the original battery.

Jon

My partner has a first gen Prius, it's a 2002 which is in every way I can determine, identical to the 2001 it replaced after somebody rear-ended her and totaled it. To my absolute amazement, the original battery is still going strong after 16 years. I replaced the 12V battery after it failed several years ago but never touched the traction battery. It's easily one of the most boring driving experiences I can ever recall but in terms of getting from point A to point B I have been astonished at the dependability. Of course now that I said that it will probably break down.

[james_s]

They also have a mode where they can shut all 16 valves while running in pure electric mode, and there is zero fuel consumption.  Due to the small size of the motor and battery, you can't drive very far like that - like 1/4 mile down a slight hill, maybe.

What is the purpose of closing all the valves? Does the engine not disengage from the transmission in pure EV mode? I'd have thought even with the compression acting like a spring that the friction losses of spinning an engine with all the valves closed would still be huge but I don't really know.

[Kevman]

They also have a mode where they can shut all 16 valves while running in pure electric mode, and there is zero fuel consumption.  Due to the small size of the motor and battery, you can't drive very far like that - like 1/4 mile down a slight hill, maybe.

What is the purpose of closing all the valves? Does the engine not disengage from the transmission in pure EV mode? I'd have thought even with the compression acting like a spring that the friction losses of spinning an engine with all the valves closed would still be huge but I don't really know.

All this talk about gas and diesel engines in an EV thread. 

Anyway, what's the alternative? If you hold the intake valve open like an unloaded air compressor the piston will hit it at TDC and there's all kinds of losses associated with opening and closing the valve over and over for no reason.

[jmelson]

What is the purpose of closing all the valves? Does the engine not disengage from the transmission in pure EV mode? I'd have thought even with the compression acting like a spring that the friction losses of spinning an engine with all the valves closed would still be huge but I don't really know.

In the Honda Civic Hybrid, the traction motor/generator is built into the flywheel of the IC engine.  So, Honda cheaped-out of the drivetrain.  (Probably to not infringe on the Toyota Prius drivetrain.)

The motor is permanently connected to the IC engine, if one is spinning, the other is, too.  With all valves closed, the friction in the engine is amazingly small.

If you want to check this out, you need an OLD car, pre-computerized drivetrain.  Put the transmission in LOW, and accelerate to, maybe 30 MPH.  Turn the ignition  off and simultaneously floor the accelerator.  Let the car coast for a few seconds, then take your foot off the accelerator.  The difference is the pumping loss of the engine throttle.  You will be amazed at how well the car coasts with the throttle wide open, and how quickly the engine brakes the car when you close the throttle.  (Note:  Do not turn the ignition back on while the car is moving, or you will likely blow the muffler up!)

So, it seems that they DID know what they were doing, and got quite low friction with all the mechanical works spinning.

The Honda Civic Hybrid does not really have a "pure EV mode", you cannot start from a standstill in pure EV, but you can run for very short distances or down a slight hill as a pure EV, or just coast with NO energy input, when plain inertia and potential energy are sufficient.

Jon

[james_s]

Well all of my cars qualify as old in that sense, newest I've ever owned is a 1990, every car I've had has a proper manual gearbox. I think I'll take your word for it though rather than actually trying that.

[nctnico]

Still I think it should read 'all valves open' and probably only the exhaust valves as to not damage the throttle and inlet because the inlet is usually made from plastic nowadays. With the valves closed you'll get compression and thus losses in the engine.

[james_s]

That was my first thought, but most modern engines are of the interference design so if the valves are left open the pistons crash and that's a really ugly situation. It may be that the valves being closed causes the pistons to behave like a reasonably efficient spring, the energy spent compressing the air is returned to the crank on the downstroke since no pumping is taking place.

I don't want to derail the thread more than I already have though.

[nctnico]

That was my first thought, but most modern engines are of the interference design so if the valves are left open the pistons crash and that's a really ugly situation. It may be that the valves being closed causes the pistons to behave like a reasonably efficient spring, the energy spent compressing the air is returned to the crank on the downstroke since no pumping is taking place.

You have a point there but the laws of thermodynamics may not agree with an closed of cylinder being an efficient spring. When a gas is being compressed, it gets hot so there must be more to it than just keeping the valves closed. But yes while interesting, this is off-topic.

[jmelson]

Still I think it should read 'all valves open' and probably only the exhaust valves as to not damage the throttle and inlet because the inlet is usually made from plastic nowadays. With the valves closed you'll get compression and thus losses in the engine.

But, the compression is (almost) exactly balanced by expansion, so the only losses are mechanical friction.  Anyway, this whole system actually works quite well, and has been rock-solid reliable, which pretty much amazes me.

Jon

[f4eru]

Yes, but it's pretty much obsolete by today's standards.
Because the entirety of the primary energy is still only gasoline, with it's very bad efficiency in a car engine of about 15%

Today, in state of the art vehicles and systems the primary energy required for moving the same car is reduced by a very huge factor:
- factor 2.5x reduction supposing an unlikely using 100% fossil fuels based electricity feeding a BEV through the grid
- factor 8x reduction supposing wind or hydro energy based electricity feeding a BEV through the grid

[boffin]

Still I think it should read 'all valves open' and probably only the exhaust valves as to not damage the throttle and inlet because the inlet is usually made from plastic nowadays. With the valves closed you'll get compression and thus losses in the engine.

But, the compression is (almost) exactly balanced by expansion, so the only losses are mechanical friction.  Anyway, this whole system actually works quite well, and has been rock-solid reliable, which pretty much amazes me.

Jon

It will be with the exhaust valves open.  Compressing air 9:1 generates a lot of heat taking energy out of the system.

[james_s]

It will be with the exhaust valves open.  Compressing air 9:1 generates a lot of heat taking energy out of the system.

Doesn't letting that air expand absorb most of that same heat? Obviously this is not 100% efficient but nothing is. With the valves open there will be pumping losses due to the restrictions, with the valves closed there will be increased friction losses due to the greater mechanical forces on the pistons and crank but some of the energy used compressing the air will be recovered as the air expands.

I'm not an expert on these matters but I'm going to assume the Honda engineers knew what they were doing and performed extensive testing to verify the scheme had a net positive result.

[jmelson]

It will be with the exhaust valves open.  Compressing air 9:1 generates a lot of heat taking energy out of the system.

Believe me, I have studied what Honda did with the Civic Hybrid, they close ALL valves during shutdown and coasting.  This actually has lower losses than with some valves open, as passing gas past open valves causes fluid friction.  If you compressed gas and then let it escape, it sure would cause losses.  (That's what big trucks do when using engine braking, they compress intake air and then let it out by opening the exhaust valves early.)
But, with all valves closed and the pistons QUICKLY cycling up and down in a hot engine block, very little energy is lost from the air to the block.
The trick is the heat of compression is almost totally balanced when the cylinder charge expands as the piston goes back down, just milliseconds later.

The Honda scheme does it by using engine oil to push the cam followers sideways so they don't push on the valve tips.  Also, engine oil is used to drive the rotary cylinder that alters the intake cam timing.  Damn intricate system, but I've never heard of it going wrong.

Jon

[f4eru]

Yay, Model 3 production is running well now :
https://www.bloomberg.com/graphics/2018-tesla-tracker/

[GeorgeOfTheJungle]

If you open the exhaust valve of a cilynder that's inactive exhaust gases would try to enter the cylinder because there's a higher pressure in the exhaust than in the cylinder.

[GeorgeOfTheJungle]

Let's try again to put this into the EV fanboys' heads: to the kWh/km figures you see on the dashboard, you've got to add the charger+battery round trip losses, this guy says the overall efficiency of a Model 3 is ~80%, which means to get the real figure you've got to divide the dashboard numbers by 0.8. For example, if your EV dashboard says 233 Wh/mile the real thing is 233/0.8 = 291 Wh/mile, or 18 kWh/100 km for the europeans.

https://youtu.be/x0MjZOR89Fk

Note that that ~ 80% figure is an average though, the real losses in a supergharger are more than that, JFYI, and charging repeatedly at a supercharger shortens the life of the battery, or, IOW, damages it. Hyundai says it very clearly in the ioniq BEV owners' manual, Tesla, IDK.

[mtdoc]

It takes a special kind of EV hater to spend their time looking through youtube videos about EVs just to find one to try and support a lost argument from weeks ago. And then to post it in multiple threads

Get over it George. It doesn’t matter whether round trip charge efficiency is 80%, 85% or 90%.  The energy effiiency and cost of ownership of a typical EV will still be far better than a typical ICE only vehicle.

We get it. You are opposed to EVs. This thread was meant to be for people with personal experiences with EVs.

[GeorgeOfTheJungle]

It takes a special kind of EV hater [...] We get it. You are opposed to EVs. This thread was meant to be for people with personal experiences with EVs.

Look, you're making things up: my twizy is now almost 7 years old. I just want the EV fanboys to learn how to count kWh. Take it easy.