MG ZS EV MY 21 - form of heating. Battery or reverse cycle?

[Colin E]

For the MY 21 model, is the air-con heating via the battey or via reverse cycle air conditioner. The user manual does not tell me.

 

[Coulomb]

I believe that the Mark 1 (pre face lift) uses a kettle (resistive heater), though that may depend on location sold. My Australian Mark 1 takes a minute or so for the heat to come through. I would expect a reverse cycle heater to take less, say 10 seconds.

 

[fred12345]

For the MY 21 model, is the air-con heating via the battey or via reverse cycle air conditioner. The user manual does not tell me.

Beyond me but what instruction manual says is that it uses the stuff below so someone else might be able to figure out what kind of system uses it...

Air conditioning refrigerant, g R1234yf 540±20

10A Electric Air Conditioning Compressor

 

[peterseddon]

My Mk2 uses the air con to cool and a resistive electric heater element in the airflow to heat the incoming air. The climate control balances to two systems the control the temperature to the set value.

 

[fred12345]

My Mk2 uses the air con to cool and a resistive electric heater element in the airflow to heat the incoming air. The climate control balances to two systems the control the temperature to the set value.

yes, the manual seems to show electric heater under No. 2

 

[Tim Green]

I think both Mk1 and Mk2 use the same basic system, although the mk2 has automatic climate control.

 

[pollenface]

The AC cools/dehumidifies the air then blows it through a resistive heating element, very inefficient.

Heating typically uses 3-4 times as much power as just running the AC in cool mode

 

[Tim Green]

You can just heat the air without cooling it first, but you will get condensation .

 

[MickeySw]

You can just heat the air without cooling it first, but you will get condensation .

As @pollenface stated, it’s the inefficient heater that’s the problem, using a heat pump instead of a resistive load is a better solution but that adds complexity and costs more.

 

[Aidanw]

The heater at least isn't just binary on/off in terms of power use.

The cold/heat is graduated for power consumption. Ignoring the blue, the white in the middle doesn't engage the heater, and then the first pale red segment will engage the heater at a low level, power cycling it frequently on/off, then at the full red heat end it is using a high power level and the power cycling keeps the heater engaged much longer.

 

[Colin E]

Thanks for all the informative responses. I'm 'cool' now without reverse cycle aircon!

 

[Deleted member 17430]

Harsh to say resistive heating is inefficient. It is generally considered that doing anything other than heating with electricity is inefficient because there will be losses to heat. Whereas heating with electric is nigh on 100% efficient.

The problem is simply that it takes a lot of energy to heat stuff up.

With a heatpump you take some (hopefully most) of that energy from somewhere else - the air outside.

No more efficient, just a different process, reducing battery consumption.

But I know what you meant ;-)

 

[Tim Green]

But any heat pump is only on or off, therefore has to be controlled on a timed on or off which is not good as the heating goes from hot to cool to try to keep a stable cabin temperature. In a word, it is not a good system for heating a car.

 

[MickeySw]

But any heat pump is only on or off, therefore has to be controlled on a timed on or off which is not good as the heating goes from hot to cool to try to keep a stable cabin temperature. In a word, it is not a good system for heating a car.

Same principle applies to a PTC heater, but curious what would you consider to be a good heating system for an EV?

 

[Deleted member 17430]

But any heat pump is only on or off, therefore has to be controlled on a timed on or off which is not good as the heating goes from hot to cool to try to keep a stable cabin temperature. In a word, it is not a good system for heating a car.

A heat pump can have variable power by using a variable speed motor... typically called an inverter heat pump. Very efficient, very quiet and avoids inrush. Quite common these days.

Even if it were a simple 100% or nothing sotuation (a common situation for a billion fridges and home heat solutions) then the on/off cycles would be smoothed by the controllor monitoring the temperature of the evaporator and condensor radiators in order to switch on before the thermal inertia has been used up. Ensuring relative comfort. At least in my Leaf I have never noticed warm and cold cycles.

But as Mickey says, a ptc is clicking on and off to keep the cabin snug just the same...

Definitely blowing fresh air over a nice warm ic engine is the best way to heat a car. Because you can choose just how much warmth you want to keep just the right temperature.

That is, if one can ignore the fossils burned to make that heat, the rest of it going off to happily warm the planet, the CO2 (and the rest) spurting out the funny pipe at the back and the money spent on acheiving all that!

 

[Coulomb]

Definitely blowing fresh air over a nice warm ic engine is the best way to heat a car.

Except also that heating is non-existent to reduced over the first few minutes of a journey. Rarely a problem for me in sunny Queensland, but it must be annoying in very cold climates.

 

[Tim Green]

in theory I suppose one could us one heat/cool heat pump as in the common aircon/heaters found in properties. But this would be expensive and as in most vehicle applications, it comes down to cost/benefit analysis. There is nothing cheaper than a length of resistance wire in an airflow, even if one adds a cheap switchmode regulator. Add in the potential repair costs and it becomes a no-brainer, especially for low cost cars such as the MG.

 

[MickeySw]

There is nothing cheaper than a length of resistance wire in an airflow

Would be surprised if MG has it working like that in an EV? Usually the PTC is used to heat water which is pumped through a heat exchanger that ‘sits’ in the airflow?

True, the heater itself can be efficient, but the heat transfer water/air isn’t and therefore requires a lot of energy to keep you cosy.

 

[Deleted member 17430]

Except also that heating is non-existent to reduced over the first few minutes of a journey.

I was being ironic.

 

[Deleted member 17430]

And yes, the air-conditioning is the heat pump in the Leaf. One system.