Maximizing efficiency of the climate control in 2014 model

[johnr]

My understanding is the 2014 model has an actual heat pump to serve as heater and air conditioner. Brilliant idea, and should use a lot less energy than resistive heating! So how does the temperature knob work? Does it actually adjust the settings of the heat pump, or does it simply combine hot and cold air like in a gasoline powered vehicle? To maximize efficiency of the climate control, would it be best to turn the knob just slightly to hot or cold (as the case may be) and turn the fan on high? Any thoughts from someone with more information on how it works?

 

[JoeS]

johnr, I wasn't aware of Mitsubishi making any changes in their heating/cooling system - much as we'd like a heat pump (like the change Nissan made in the Leaf), I'm afraid what we have is still quite basic. Whereas the aircon is relatively efficient and has only a small effect on range, the heater is a plain old resistive water heater that sucks significant energy out of the main pack. I'd love to be proven wrong - where did you hear about the heat pump?

 

[Mart]

Sad really, and an ode to large bureaucracies, that Mitsubishi makes some of the most efficient home heat pumps in the world, but can't cross barriers among business divisions to get them into the automotive sector.

 

[sandange]

Having recently bought a new i Miev

I looked at a Leaf and discovered that the
base model Leaf does not include the heat pump heater, fast charge capability or the smart phone remote control.

There also was a price difference of more than $5,000 (here in Quebec Canada)
Between the i Miev and the base model Leaf.

I believe they are keeping things status quo - trying to keep the pricing down.

 

[PV1]

Easy way to find out if there is a heat pump. With the car in READY, turn the fan on low and turn the heat on, about a minute or two at each heat position. You can't really hear the heater's water pump, but you can definitely hear the AC compressor run while parked. Just listen for the compressor to kick on. If the car is throwing heat and you don't hear anything, it's still a resistance heater like the 2012.

Anybody else find it amusing that the AC compressor almost makes the i-MiEV sound like an idling 3-cylinder?

 

[fjpod]

I never hear my AC compressor while in the car...and never really noticed it outside either.

 

[offgridQLD]

Making it sound like a heat pump (or R cycle valve) on refrigeration pump is a big deal. It's so common and simple (like being wowed that your TV came with a remote control ). Its hard to find a home air conditioner without RC feature. It's more or less standard.

Its not the cost or complexity I would say its more to do with the limitations of a heat pump to operate effectively in very low temps.Even a low temp Optimized heat pump is only good to it rated capacity down to about 5 deg C and down to only 60% capacity at -8 deg C. Conventional heat pumps are only good for full output down to about 8 deg C .

I would love a RC valve on the air conditioner on my Imiev but I live in Subtropical area with mild winters temps below 8C are only for a few hrs overnight on a cool clear night and winter day temps 15C would even be rare . So a RC valve would work well. Some parts of the world would most likely still need the (kettle) resistive water heater for cold conditions at or below freezing.

Kurt.

 

[johnr]

I was going by what was said in the news release, "Comfort and convenience features included on every Mitsubishi i-MiEV include a specially-designed highly energy-efficient HVAC system consisting of an electric manual air conditioner with micron filter and an electric compressor cabin heater" - see http://media.mitsubishicars.com/releases/31f1c4c1-3f67-479a-8bbe-edc0cdebe8b9

But apparently they either had changed the specifications prior to production and failed to edit the wording, or something got lost in the translation - seems it's a plain old resistive heater after-all. Well, at least we have heated seats!

Well I'd still like to find out how I could increase the fan speed without causing the A/C or heater to use more energy. I used to have a Leaf and if I increased the fan speed it would cause the A/C to use more energy, so I was wondering whether this car is the same in that respect. Has anyone developed an energy meter that can be installed in the car? If so, I'd get one and figure this out myself.

 

[PV1]

Has anyone developed an energy meter that can be installed in the car? If so, I'd get one and figure this out myself.

Yep. It's an app called CaniOn. All you need is an Android phone and a bluetooth OBD adapter, such as the scantools OBDLink MX.

A few months ago, heater consumption was added, and just recently AC usage was added. This is also a great tool in watching battery temperature, voltage, energy consumption, energy regenerated, instantaneous and average energy efficiency, everything you want to know about the car's high-voltage system.

 

[HParkEV]

...
Well I'd still like to find out how I could increase the fan speed without causing the A/C or heater to use more energy. I used to have a Leaf and if I increased the fan speed it would cause the A/C to use more energy, so I was wondering whether this car is the same in that respect. Has anyone developed an energy meter that can be installed in the car? If so, I'd get one and figure this out myself.

Wouldn't we all love that... unfortunately you are asking for a free lunch.

Laws of thermodynamics say that if you put more air through a heat exchanger (fan speed higher) then you will pull more heat out of the heater or put more heat into the A/C evaporator. Therefore, the device will have to work harder (longer duty cycle) in order to maintain the temperature gradient you selected on the temperature knob. Therefore, it must draw more energy.
If you want to draw roughly the same energy with a higher fan speed, then the only solution is to at the same time decrease the temperature gradient (turn up the temp in A/C mode or turn it down in heater mode).

 

[johnr]

PV1:
I was just reading about CANiON. Hadn't realized it also shows energy usage now - this sounds very useful. I'll have to either upgrade my phone first (it's running Android 2.3) or get a new Android device. I was thinking of ordering a new GPS stereo unit which runs Android 4 - this would be one more reason to do so.

@ HParkEV:
Thanks - so it seems I should be able to minimize the energy usage by increasing the fan speed and setting the temperature closer to the neutral point rather than the coldest setting. But just to make sure - it's not going to try mixing in a little heat from the heater if it's set to recirculating mode and the temperature is set near the neutral point?

 

[Don]

Thanks - so it seems I should be able to minimize the energy usage by increasing the fan speed and setting the temperature closer to the neutral point rather than the coldest setting. But just to make sure - it's not going to try mixing in a little heat from the heater if it's set to recirculating mode and the temperature is set near the neutral point?

After 3 hot summers, we've found the best comfort/energy usage combination is to set the A/C temp dial one click from neutral and the fan speed at the midpoint. Even on 95 degree days this seems to do fine and reduces the range by only about 10%. When we get into a hot car, we hit the 'MAX' button for 2 or 3 minutes and then turn it off

The fan speed has a greater effect on power use than the temp dial in my experience

Don