Any idea why the HEATER draws so much POWER?

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lotusman

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Joined
Oct 12, 2013
Messages
19
After investing so much in making a whiz bang car, the FFE falls flat on its face when simply heating up the passenger compartment.

Seriously, how much does this thing draw, 5,000 watts? For it to drop range so much, it must draw 5,000 to 10,000 watts.

My range here in the winter drops from 65 to 35 when I put the heat on. thats like 10 kw of energy.

I can deal with the limited range, the low top speed, the horribly designed battery placement that eats the entire trunk, but not being able to use the darn heat just kills this car. The other day I had my daughter and wife with me and I was embarrassed to explain why we had to be shivering in daddy's shiny new car.

Good thing I only pay $160 a month for this lease.
 
It's a resistive heater. Very inefficient to be sure. If you can it's best to pre condition either by go times or remote start that way the cabin is at least somewhat warm and your using grid power to heat rather than battery. I do agree about the battery placement but taking out that plastic/foam organizer makes the room not too bad. As far as top speed goes I have no problem with that. I live in LA and I rarely ever touch 80 on the speedo. Kills the range anyway. :)
 
I feel your pain. This would be a major issue for me as well, but I have overcome it by being able to charge almost everywhere I go. I have a portable Level II charging solution, and almost all of my friend's and family's places have a 30 or 50 amp 240V outlet. Without this ability to Level II charge everywhere I go, I would be feeling some regret over the winter range. I realize this may not be a possibility for you, but it has made the car for me.

As far as the heater power draw, I believe 5 kW is the quoted figure. The way I have understood it is that you have to think about how much energy an ICE uses. The EV is very efficient, and thus, using the heat is comparatively a large draw on your battery. An ICE uses much more energy, and throws away a lot of it as heat. So heating the ICE doesn't make a noticeable impact on the range. It was throwing the heat away in the radiator before, and now it's just using it in the cabin. The EV wasn't throwing away the energy through the radiator before, and now it's drawing from the battery to heat the cabin.
 
sefs said:
heating the ICE doesn't make a noticeable impact on the range. It was throwing the heat away in the radiator before, and now it's just using it in the cabin.
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Heating an ICE has absolutely no impact on its range. There is no difference in "draw" in the energy being consumed by the car when heating the cabin. The engine heat, otherwise wasted into the atmosphere via the radiator, is simply re-directed into the cabin.
 
lotusman said:
My range here in the winter drops from 65 to 35 when I put the heat on. thats like 10 kw of energy.
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You mean 10 kWh (kilowatt-hours), not 10 kW (kilowatts).

A watt is just a measure of energy level (somewhat like the rate of which the water might flow from a reservoir). A watt-hour is a measure of actual energy (somewhat like the total volume of water in the reservoir which, in a way, represents the potential for various possible "flows" from it).

The "watt-hour" concept simply normalizes the idea of energy against a fixed duration of time (an hour). Going with our water analogy, a "1 watt-hour reservoir" could drain at the rate of 1 watt for 1 hour, at which point the reservoir would be empty. But the "fixed" nature of the normalization is only conceptual, which is why a watt-hour has nothing to do with an actual hour of time elapsing. The reservoir could also be drained at the rate of 2 watts for 30 minutes, or 4 watts for 15 minutes, or even at 1/2 watt for 2 hours. The amount of energy is identical (1 watt-hour), merely released at different rates, and over different durations.

This is all something like the kilowatt-hours of energy stored in the FFE battery, which the car consumes by the watt, converting various "flows" of energy from the battery (depending on driving needs) into mechanical motion, cabin heat, etc..
 
When something is inefficient, the byproduct of the inefficientcy is usually heat (in particular to the discussion topic). As everyone has stated, ICE cars are extremely inefficient so to heat the cabin comes at no additional cost.
So if the FFE is inefficient when heating the cabin, it would have to be heat that never makes it to the cabin. Which I don't think is all that large. I think the issue is really that it just takes a lot of energy to heat the cabin in cold weather.

I don't know for certain, but I showed my car to an HVAC engineer from another automotive company who believed it was likely an oil heater, which would explain why the current draw is so high when first turned, and then tapers off depending on how much heating it has to do...i.e. how cold it is outside. There is a guage you can configure on your left hand display that shows the instantaneous energy draw for climate control. Open that up and it will give you a better idea of where your energy is going.

A heat pump would be a better option as there is no oil to pre-heat (assuming it is an oil heater). Other heating system alternatives are just alternate ways of storing energy for heat.

Anyway, I don't think the FFE heater is any different than Volt or Leaf. It simply draws alot because its cold outside.
 
davideos said:
Anyway, I don't think the FFE heater is any different than Volt or Leaf. It simply draws alot because its cold outside.
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The energy draw also seems to be more than 5 kW since the energy display scale indeed goes to 5 kW, but then also has a little plus sign (+) that will turn on if you watch it carefully. We don't know how much more the plus sign indicates, but lets hope that it is only marginally more.
 
davideos said:
A heat pump would be a better option as there is no oil to pre-heat (assuming it is an oil heater). Other heating system alternatives are just alternate ways of storing energy for heat.

Anyway, I don't think the FFE heater is any different than Volt or Leaf. It simply draws alot because its cold outside.
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I believe that as of the 2013 model the Leaf uses a heat pump. Volt uses resistive, but it has the gasoline engine as a backup. It would have been good for Ford to have used a heat pump.
 
My HVAC friend who is familiar with the EV heating and cooling in general, not specifically the FFE, said that a heat pump is great because it can be used for heating and cooling; however, it is difficult to implement because of all the valves and hoses needed. This was not an extensive analysis. When they finally do it, the end result will probably save some weight since it will be a 2 in 1. How much savings in energy that will be realized is unknown, but I can't beleive it would be all that much. However, that said, my comment is based on simple thermo dynamic principles and not on these systems in particular; and the Leaf owners seem to be pretty happy with theirs....with respect to energy consumption. I'll have to find a non biased article on the difference in efficientcies between the two.

Edit
Ok, I found a source. What I forgot to consider was that a heat pump doesn't generate heat, but rather, it moves heat. For resistive heat, the coefficient of performance is 1.0...or in other words, one joule of electrical energy produces 1 joule of heat. A heat pump has a coefficient of performance that is 3 to 4 times greater...and the warmer it is outside, the higher the COP. Anyway, Wikipedia has a lengthy article on it.

So yeah, I'd much rather have a heat pump :)
 
I also read new Leaf uses heat pump.

I have a mini split heatpump heating an addition on my house, its an inverter model, so it adjusts draw depending on requirements. I heat a 400 SF room and it consumes between 1,400 and 6,000 watts on high.

So they seem to be much more efficient.
 
I read that the leaf does actually have it.

The heat pump should be much better; however, if temperatures drop too low, the performance nears that of resistive heating. So for those of you with temperatures below zero, your energy savings wouldn't be as much.
 
The converse of the heater and its terrible inefficiency is the air conditioning in the FFE. Not only is amazingly efficient, but I had it in Palm Springs in 110 degree heat and it cooled the interior faster than any car I have owned. If not for the cost, I would think that all manufacturers would move to electric compressors.
 
I know my idea would have little effect on a stationary vehicle but I don't understand why we couldn't harness the motion of the car it's self. Driven off the drive shafts (somehow... remember I'm thinking, and that's dangerous) to turn a fluid turbine of a sort. There are many fluids that can react to pressure by generating heat, or by friction with heat being a by product. Heck even harnessing the heat from the brakes to the cabin is an idea, though I doubt most people would ride the brakes hard enough to do such a thing. Also i'm aware that my ideas only work above a certain temp while in motion at that. Magnetics and fluids can work wonders, take ferofluid for example.

Just thinking out loud.
 
Anything you do to create heat from a moving portion of the car is just going to take more energy to move the car. Harnessing energy from brakes or even the batteries, motor, or controller electronics, probably won't yeild enough to keep you warm. Although the electric heater isn't the most efficient method, it isn't too far away from what a heat-pump can do; especially at freezing temperatures. Most of the energy savings from the heat pump is the initial heat-up period.

One of the projects that Ford is involved with is a thermal battery by MIT, which will not even use the electric battery: http://www.technologyreview.com/news/513466/novel-heating-system-could-improve-electric-cars-range/

But don't think we're the only ones freezing while not using our heaters. This was an interesting read...
http://www.greencarreports.com/news/1089040_life-with-tesla-model-s-east-coast-road-trip-freeze-in-slow-lane-or-languish-at-nissan-dealers

Anyway, in a few years, there will be better heaters out there. Hopefully someone will make me a retro-fit kit :)
 
az erik said:
I know my idea would have little effect on a stationary vehicle but I don't understand why we couldn't harness the motion of the car it's self. Driven off the drive shafts (somehow... remember I'm thinking, and that's dangerous) to turn a fluid turbine of a sort. There are many fluids that can react to pressure by generating heat, or by friction with heat being a by product. Heck even harnessing the heat from the brakes to the cabin is an idea, though I doubt most people would ride the brakes hard enough to do such a thing. Also i'm aware that my ideas only work above a certain temp while in motion at that. Magnetics and fluids can work wonders, take ferofluid for example.

Just thinking out loud.
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Unfortunately that wouldn't help. If you harness the motion of the car (or any of its moving parts) you add to the drag, and ultimately the energy comes from the battery. It's actually more efficient to use the inefficient resistive heater (heat pump is better, of course)

The exception would be if you could somehow capture heat that is wasted, for example heating of the motor or battery. But on cold days, the battery needs to heat itself. But maybe capturing otherwise wasted heating loss of the motor could be of some benefit.

But as I said, I think the first and easiest step is to scrap the resistive heater and replace it with a heat pump...like Nissan has already done.
 
davideos said:
But don't think we're the only ones freezing while not using our heaters. This was an interesting read...
http://www.greencarreports.com/news/1089040_life-with-tesla-model-s-east-coast-road-trip-freeze-in-slow-lane-or-languish-at-nissan-dealers
Click to expand...

What a great article. So nice to see that we are not alone with the range issue. I've toyed with the idea of trying to make a long distance trip in the FFE. After seeing the range drop so much in the winter, that would have to be a summer project. And I guess I could complain about the lack of Level 2 chargers around the Midwest. I am envious of Canadians with their well placed charging stations.
 
How can I make the HVAC system remember the way I left it when I turned the car off?
When I wake the car up for a new trip, usually the fan comes on 'way higher than I ever want it, even though I had that system OFF when I parked and shut down, and I must reach over and reset it every time: wasteful (and swearing at it does not help, evidently).
Better if it would stay off until I want it to run.

Is there an option I have not seen yet?

(Slightly off topic, by my Search did not turn up a relevant match just now.)
 
When I just want some outside air, I typically turn the temp to LO and then the AC off. The fan will come on full. I then turn that all the way down to 1 bar. If I turn it off and back on again by the HVAC switch, it always comes back on full. If I just press the decrease-fan-speed-button, it will come back on low, just the way I had left it.

Not exactly your scenario, but maybe there is some experimenting you can do in that regard.
 
JTCalif said:
How can I make the HVAC system remember the way I left it when I turned the car off?
When I wake the car up for a new trip, usually the fan comes on 'way higher than I ever want it, even though I had that system OFF when I parked and shut down, and I must reach over and reset it every time: wasteful (and swearing at it does not help, evidently).
Better if it would stay off until I want it to run.

Is there an option I have not seen yet?
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No, it's just buggy, and you're probably suffering from this:
http://www.myfocuselectric.com/forum/viewtopic.php?f=14&t=1256

Whenever this happens to me (which is once every few weeks, or sometimes more often), I reboot MFT by pulling it's fuse. While MFT is "disabled" (the fuse pulled), you'll notice that turning on the car simply always starts with climate off, no matter what state you left it with (proving, IMO, that MFT is responsible for restoring the climate state, and is thus also responsible when the climate starts to misbehave). Anyway, after you put the fuse back it, and once MFT reboots, you should find the climate goes back to remembering its previous settings whenever you turn the car on (well, until it starts forgetting again).

I've been through this routine several times. Rebooting MFT works like a charm for this every time. (Just like they say in Anchorman, "60% of the time, it works every time".)

Also, another trick to using the climate, is to always turn it on by pressing the "fan low" button (instead of any other button, like the power button or the A/C button). If you press the other buttons, the climate will come on on full blast. If you press fan low, for whenever reason, it comes on not full blast.

----

Edit: You can actually use either the manual "fan low" or "fan high" buttons to turn on the climate, and it will come on at the lowest fan setting.
 

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