4th generation coming 2015!

Telsa and Leaf take a huge range hit. Volt also use gas when below 60 deg F (?). It can preheat from plug but still use gas for heat shortly after driven off. Efficiency drops either ways.

My PiP average EV efficiency (year round average) was 132 MPGe in NY. Gas was 56 MPG. NJ traffic yields better but I don't have a full year data yet.

It is very rewarding to use each fuel when they are most suitable.

 

As I said, efficiency in cold takes about an additional 10% hit over a gas car. Average over the winter is about a 30% range reduction. Gas cars take about a 20% hit to range, although that is less of an issue.
The Volt's gas engine doesn't kick in until 28 or 15 degrees depending upon user settings. Not sure where you got 60 degrees from.

 

The next ICE will be 40% or so thermally efficient. That's under ideal operating conditions. So 60% or more of the energy in the burned gasoline is getting wasted as heat. Might as well use it to heat the cabin.

The Prius already has already supplemental electric heaters for when the ICE isn't heated up. Ones large enough for heating will cost more and just suck the SOC down. Then the ICE has to start up to replenish the charge. Less energy losses is just firing up the ICE for heat.

Heat pumps may start appearing in future hybrids. Right now, their cost is only warranted in BEVs, because the battery electricity is their only source for heat.

 

Thanks all for the info.

I still suspect (a feeling, not a fact)(I am not an engineer) that a very small, dedicated auxilliary air-cooled power source, running at a constant optimum speed, burning the cleanest fuel possible (hydrogen, natural gas, propane, whatever) with no chore other than to run a generator, would be a potential solution. The generator would only charge the battery, supplemented by plug-in, re-gen downhill, coasting and breaking.

The Tesla battery weighs 1200 pounds (according to the Velocity Network highlighting the Tesla S). There is no need to lug around a 1200 pound 300 mile charge battery when only running the children to school, or the grocery. Have a dash dial to select when low battery needs are anticipated. Another setting when extreme winter heating and summer cooling are anticipated, and another for distant travel. The small power source would run only in accordance with the battery need commensurate with the driver's expectations. As it currently stands, engineers are having to design for the most stringent, maximum SOC for high demand conditions, when the vast majority of our needs are low demand. IOW, designing to offset range anxiety, when the vast majority of our travel is low.

Just a thought.

 

Yup, cogeneration of both heat and power. For EVs, the heat loss is at the power plant and there is no way it'll make it into the cabin.

That's why PiP EV miles are designed for short trips with speed below 62 MPH.

A small pack doesn't rob cargo space nor gas MPG.

You also don't have vampire loss for having a big battery pack.

Different design goals. Pure EV enthusiasts didn't get the point. All they cared for was all continuous electric range.

 

From a pure efficiency standpoint, I agree completely with you. Hauling around a battery pack that is big enough to handle all your needs is less efficient than only hauling around as much battery as you need for the immediate rquirements.

Humans don't work that way though.
How often do you only put as much gas in the tank to get you as far as you need to go that day?
It really is no different, only the scale is larger.

The generator running at a constant, most efficient speed, is a great idea, although that generator is still less efficient that an electric motor.

In the case of Tesla, the battery pack isn't simply dead weight. It adds to the handling and safety of the car as well.

Yes, the weight is a negative, but unlike a gas tank, it uses that weight as a positive as well. Overall, the Model S weighs only slightly more than the Mercedes S class and other large luxury cars.

 

Here is a blurb about the first Leaf heater

but things change in the 2013 or newer that has a heat pump

 

i wonder how much juice that setup uses.

 

depends on temperature difference. As much as similarly sized A/C in Prius with similar diff.

 

wow, that's excellent.

 

A heat pump is much more efficient that the old fashioned heater.
Keep in mind though, the AC has a smaller temperature difference to overcome than the heater.
This is the bulk of the reason for the 10% additional efficiency loss for EVs in the winter.

 

hmm, mine loses 10% without heating.

 

Sorry, I guess I wasn't clear. EVs, mostly because of heating, loose 10% efficiency in winter in addition to the efficiency hit all cars take in the winter.

 

ah, thank you. that seems a bit more than prius a/c. but surely, the heat pump is much more efficient than resistance?

 

Good discussion. I learned something.

Remember the old VW bug with the heaters extracting heat (a very little heat) off of the air cooler engine? Even in the south, the inside never got comfortable.

 

How are you doing, compared to EPA rating of the Model S?

 

It is much more efficient than using a resistance heater for the entire cabin. That is the reason the 2011 & 2012 Leaf had a much heavier range hit from winter.
Once they switched to a heat pump it got better.

The seat heaters (which I believe are resistance) are the most efficient, because you are heating up the surface of the from seats only. The gains from heating such a small area outweigh the lower efficiency.

 

Unless you are "stealing" energy from the ambient air, electric heat is the same, pump or just resistive. Kind of hard to efficiently steal energy from -20 deg. air. There is a hint here. Note that no manufacturer tries very hard to sell electric cars in Canada. Other than Vancouver, where it doesn't get cold.

 

Anecdotally with 3 winters on one car, 2 on another.
The range loss varies depending upon temperatures. Winter in Southern California will have much less impact than winter in Minnesota.

I have spoken with numerous other ev owners as well. For any EV that uses heat pumps it seems pretty consistent.

*******edit*******

Here is a good example: EV Winter Range Loss Is Both Fact & Fiction

My experiences come from very little change to typical winter behavior learned from driving an ICE for all my life. I tend to use cabin heat moe than seat heaters, the car is parked in an insulated, but not heated garage. I preheat the car about 25% of the time.

Those that have a heated garage, preheat while plugged in more consistently, make better use of the seat heaters, typically see less of a range hit. Those that park outdoors, never use seat heaters but blast cabin heat would, I would guess, see more of a hit.

While it is true you are taking heat from ambient air, a heat pump takes much less energy to provide that heat than resistance heating.
You raise an excellent point about temperature though. At about 5-10 degrees (Fahrenheit) a heat pump is no longer more efficient than resistance heat.

 

I should have been more clear.

For the total miles you have on the Model S, what is your average MPGe? If you don't have lifetime figure, a full year of data is just as good.

I also wonder how you did with other cars. Were you able to beat EPA figure or always lower?