Heat...did we reach a conclusion on this?

[fjpod]

I can't seem to find the last thread where we were discussing this, but here goes again...

We all know that when turning on the heat, the higher we put the fan speed, the faster the RR goes down. But when adjusting the temp control from green to red, the RR does not change. Does this imply that any temp setting draws the same amount of power? Does Mitsu mix in cold air to get the desired temp as in normal ICE cars?

If so, it would seem to be more efficient to keep the setting high, although many posters state they keep it as low as possible for economy sake. I have not been able to determine if the fuel gauge goes down faster one way or the other. Has anybody measured the power draw of the heater at different temp settings? The amp meter on the dash doesn't seem to vary when adjusting the temp knob.

 

[MLucas]

I find it best to keep the Fan selector (middle knob) on AUTO and use the Temp selector (top knob) to adjust the heat settings. I generally keep the Flow selector (bottom knob) on AUTO which directs the flow to the feet when heating, but sometimes I need it to defrost and move it to one of the defrost settings. If you do this and watch the RR meter, you'll see some of the range return. The range returns because the AUTO select will keep the vehicle at a certain temp and can cycle on and on off, instead of constantly blowing. The amp meter above the speedometer definitely reacts according to the temperature set. The first notch hardly shows anything, the second notch lifts the ampmeter to about an 1/8 of the green Eco zone and the third notch will lift it to a quarter of the Eco zone. If you have your HVAC settings on AUTO the ampmeter will only show the affect when the car is heating.

Yes, the fuel gauge definitely goes down faster the higher the setting. Last night, at -13c /8f I set the heat to the third notch, I had 14 bars on the power meter - after arriving home I had only 1. That was the worst range I had ever gotten, usually I can make it on 8 bars with the heat on the first notch. Part of the decrease in range was also strong winds and extreme cold temperatures, but definitely the other part was the higher heat setting. This morning, I made the same trip and with -13c and the heater on the first notch I made it to work with my normal 8 bars which is my winter average.

 

[fjpod]

I get what you are saying about using auto because it will lower the fan speed automatically. I'm going to try that for a few days.

It has been my observation though that reducing the temp knob itself when you have a certain fan setting does nothing to the RR....which is leads me to think that cold air from outside the car is being used to reduce the temperature. I hope I am wrong about this.

Anybody else?

 

[tonymil]

I had the same worry about the a/c, if you move the temp setting off of "coldest" are you just mixing warm air from the outside with the cold air from the a/c? I didn't really get an adequate response to that either.

With the heater, my practice is to keep the temp setting at the hottest level and manually adjust the fan based on my comfort level. I wear a heated vest so I direct almost all the heater air at my feet/legs and this allows me to keep the fan on only one or two notches from "off" once things have warmed up.

 

[fjpod]

I had the same worry about the a/c, if you move the temp setting off of "coldest" are you just mixing warm air from the outside with the cold air from the a/c? I didn't really get an adequate response to that either.

With the heater, my practice is to keep the temp setting at the hottest level and manually adjust the fan based on my comfort level. I wear a heated vest so I direct almost all the heater air at my feet/legs and this allows me to keep the fan on only one or two notches from "off" once things have warmed up.

That's exactly what I have been doing (but not wearing the vest)...keeping the temp way up and the fan way down...but I have no evidence that this saves more power.

 

[Llecentaur]

My experience is +2 for heat and fan on auto.

Most times i use the setting to direct heat to feet and front while directing two air ducts to my hands on the steering wheel. It does make a difference

I have also isolated the heating system, although the isolation of the main unit is not perfect because i could not take off the black plastic panel fully (clips were breaking !)

There is thread on diesel heating conversion, I think it is a must specially as our batteries will start aging in a few years, diesel or bioethanol heating should allow us to hold on until a new breed of batteries hopefully more powerful and easy to install will be availabke.

 

[Don]

It has been my observation though that reducing the temp knob itself when you have a certain fan setting does nothing to the RR....which is leads me to think that cold air from outside the car is being used to reduce the temperature. I hope I am wrong about this.

Anybody else?

I *think* when the heat is turned on (no matter how far into the red you have the temp dial set) the RR meter gives you a number based on the fact that the heater element is drawing current all the time. I *suspect* if it got warm enough in the car for the heating element to begin cycling on and off, the RR meter would begin to give you back some of that range

I certainly *hope* they're not balancing the heat with cold air from either outside or the A/C to control the amount of heat . . . . heat is so difficult to come by that if you had too much, you'd surely cut back on the amps the heater is consuming and not add cold air

Don

 

[Vike]

As far as I can tell, the most efficient behavior I see is fan on Auto and set the temp to desired level; as mentioned elsewhere here, the HVAC cycles accordingly. On my short commute, I pre-heat the cabin at home and run to work w/just seat heater, but blast it on Max leaving my office garage until it's moderately comfortable. I plug in and charge for the minimum 0.5 hours every night so I can pre-heat in the morning. Hopefully all that's not too hard on the batteries.

Didn't get enough summer driving in last year to reach firm conclusions on A/C, but I'm guessing a similar strategy will work there. I do know that even blasting at MAX, A/C draw was nothing like the heater's been. Range-wise, it's just a different (and noticeably more limited) car in the winter.

 

[peterdambier]

Our 2010 i-MiEV does not heat or A/C while charging. That is why I refurbished a portable 2kW heater and put it into the co-drivers foot well. Mostly I run it on 1kW.

The external heater and the i-MiEV temperature sensor step on each other's feet. No automatic. I have to select defog resulting in A/C running or defog plus creature comfort and torn on a bit of heat to keep comfortable and fog free for some time at least but very often I need A/C to keep the windows free.

Interestingly enough when the car is not moving the i-MiEV heater works great.

Relating power consumption and heater is tricky at least. There is a switch in the heater and when it connects it draws power as if I was driving. Most of the time there is heat stored in the heater so it does not consume power at all. That is why you dont see anything changing when playing with the controls. But beware the turtle takes notes and next time she will inform us about our guessed power consumption. :lol:

 

[Don]

I've found that the RR meter separates the heater current from the drive motor current - In other words, you can do one trip with the heater blasting, recharge and the RR meter will give you it's new prediction based only on the current the drive motor used on your last trip . . . . it doesn't count the heater current which would give you a much lower RR calculation

Don

 

[marlon]

Don:

Yes, my experience exactly. The car seems to do two parallel calculations, with and without heat. Turning the heat on or off changes the RR to match. Generally, turning the heater on (I usually turn it full blast) will cut the RR at least 25%, more often close to 33%, and sometimes even more.

I found changing the temp gauge does have some effect on the RR, but its not that dramatic. Most of the change I mention above comes with turning on the fan, raising it to full blast takes some more. Changing the temp seems to change it only slightly.

On a related note, I think the heat current draw is constantly changing based on what it needs. If I run the heat full blast, when I first start up, the amp meter goes about one third into the eco zone (outside temp usually about 25-35 F). After the car warms up it goes down some. However, even after its warm, when I stop at a traffic light, the needle will dance back and forth between almost zero and 25 to 30% of the eco zone.

Does this fit others experience?

I haven't had the miev in warm weather yet (I got it in November) but I remember another post that said 20 minutes of heat costs one bar and 40 minutes of AC costs 1 bar. This seems to indicate AC draws more, contridicting the above. I imagine it depends how hot or cold the day is.

 

[Vike]

I haven't had the miev in warm weather yet (I got it in November) but I remember another post that said 20 minutes of heat costs one bar and 40 minutes of AC costs 1 bar. This seems to indicate AC draws more, contridicting the above. I imagine it depends how hot or cold the day is.

Umm, little problem with the math there. If 20mins heat = 40mins A/C, that means A/C draws half as much power. And that doesn't surprise me - I used A/C last September, even on Max it didn't seem to impact range like the heater does.

 

[aarond12]

When (gently) using heat, I notice the Eco gauge rising a bit at a standstill. Then, after a few seconds, it drops back down. I'm assuming the heat is heating water, and the water is the carrier of the heat to the heat exchangers. I did notice if I pre-heat my car (I love that!) that I can leave the heat on the lowest heat setting and it's adequate. When coming home from work without pre-heat, I have to be more aggressive with the heat setting.

We've had a very warm January and February so far here in Dallas. Today's high is going to be around 70°F, which is way over the normal, so my heat usage has been minimal. Nice to hear that the A/C uses less power. As a Texas resident, though, I don't turn on the A/C until it gets around 90°F. :twisted:

 

[marlon]

Dear Vike:

You are right on the heat and AC. I reversed my numbers.

Marlon

 

[jaraczs]

I can attest to Marlon and Aarond12. The vehicle has 1/2 gallon of heater fluid that needs to be warmed up first. So, even at the first notch, the heater draws maximum (5 kW, I think) power to reach that "lowest" temperature. After that, it cycles as controlled by thermostat.

In addition, you can get a feel of the heater fluid temperature when you reach down on the driver side
and locate the aluminum pipes that direct the hot fluid in-and-out the heater core. The more notches on heater setting, the hotter the liquid/pipes.

In opposition to fjpod, I tend to use the lowest temperature setting possible because I believe the bigger temperature gradient will cause more heat leak in the system, although my heater and pipes are all insulated. To save on heating, I found the recirculation helps although it causes the windows to fog, starting from the back. The recirculation is very simple (=clever) system located behind the glove box (also cabin air filter). It controls whether the air coming into the heater core will enter from outside or inside. If it comes from inside, it is already pre-warmed, hence using less energy.

During one of the coldest nights in January 2013, when temp. -8 to -10C (14-17F), I had to resort to gloves and hat and used NO HEAT to conserve energy to complete the travel mission at speeds of max 45 MPH. I made 62 miles with 5 on RR. Still beating EPA but not comfortable, although I was surprised myself that I could sustain the inconvenience.

My take on winter driving is (aligned with many from this forum) that: Why should I use electricity to heat my car when I use fossil (natural gas) to heat my home? Electricity is expensive for heating!! Particularly when it comes from a fancy battery. Our iMiEV is so super efficient in converting electricity into vehicle propulsion but electric heating is not. And it cannot be. Heat pump - maybe but you cannot use it below - say 40F. Pure electric EV with no room for gas is purist's request. For practical life, the fuel required to warmup the battery to restore its full capacity and keep passengers warm would have not less than 112 MPG efficiency, the best usage of fossil or biofuel in a car.

Winter driving for all EV's (including Tesla) provides the shortest range and it determines all year long range. So, if your daily need is 60 miles, it is of no relevance that iMiEV will make 90 miles in summer. Drivers will have hard time to make 60-mile distance in Winter with heater on.

 

[BenBrown]

I haven't heard from dealer/about shipping my car yet, but am trying to learn everything I can before it gets here... Topic HEAT!!!
My main default source for the present is 120v that I've plugged into to charge a car shared Leaf. Secondary source is a pv bank that supplies a Level 2 system with about 12 plugs.

We've had some nasty cold weather in Michigan (-12F) with serious winds. Normally I heat the Leaf and enjoy the warmth while charging. I generally don't turn on the heat. With such bitter cold, I actually had to drive around a bit, before the battery seemed warm enough to charge normally. Once charging normally I could turn the heat on low, the seat heating and be comfortable within 10-15 minutes.

Somewhere I saw a post, of the i-miev heater unit. It did not look like it came from the maker with much insulation. Any idea why not? Somewhere else here someone posted photos of isolating/insulating the heater core. I wonder has anyone tried that here and what difference was noticed? Was it hard to do?

That Really has my interest.

Ben

 

[Don]

Somewhere I saw a post, of the i-miev heater unit. It did not look like it came from the maker with much insulation. Any idea why not?

Cost I'm guessing. When the car as introduced, it was a basic $12K econo-box converted to an EV . . . . but with a $30K price tag. Every dollar you add to the production cost just made things worse. Why spend money which A.) Most owners would never notice because of their milder climates and B.) Money which doesn't really buy you much more heat or range?

Somewhere else here someone posted photos of isolating/insulating the heater core. I wonder has anyone tried that here and what difference was noticed? Was it hard to do?

There are a couple of extensive threads here discussing this very thing

Don

 

[sandange]

Hi Ben

Here is the link to insulating the heater and pipes.

It's a long thread with other ideas in it as well.

http://myimiev.com/forum/viewtopic.php?f=9&t=224&start=30


Personally I found it just wasn't enough for our climate.