HV Heating and Cooling

[Mark Holmes]

Question for someone...an apologies if it’s a stupid question, but does the car use more HV battery if you have the heating turned up hotter and the fans on at a higher speed.
Also does have the cold air use more or less power than heating.
The truth of the question is that I never paid to much attention to the specifics other then when you power on the system your mileage drops, haven’t given to much thought about the impact from the actual settings when powered on..
Can anyone advise?

 

[Mgkev]

I guess you could watch the power consumption reading and compare them to heating and cooling. I’d put money on heating using more power than cooling, one of the reasons range is down in the winter.

 

[Mark Holmes]

I guess you could watch the power consumption reading and compare them to heating and cooling. I’d put money on heating using more power than cooling, one of the reasons range is down in the winter.

Yes I guess, but the amps used bounces about too much to really see what’s truly being used...

 

[Mgkev]

Yeah I’ve just been outside and checked, forget what I said earlier

 

[Chrispydoc]

You don't get "owt for nowt". My impression has been that having the air-con on uses most, followed by heating, followed by just fans. Thats how I imagine it.......but I could be wrong.
Any electricity you use from the 12 volt, will ultimately have to be topped up by the big battery/ re-charging.

Our cars are still far more efficient than ICE cars, I was reminded of this on New Years eve where a lot of folk were waiting for takeaways at our local Chinese restaurant. It was a cold evening so most cars had their engines running. I was sat there nice and warm, listening to the radio and I think my car only used up about 2 miles of range....in half and hour. Not bad at all.

 

[Kithmo]

"owt fer nowt" is the Yorkshire terminology, owt = anything, fer = for, nowt = nothing Chris.
Not sure if the MG has 12v AC or if it's a HV system, but on the Prius the AC electric pump is actually run off the 12v system so uses very little HV battery, heating is obviously off the ICE.
My guess for the MG would be HV heating and 12v fans and AC.

 

[kiltox]

The heater uses the most energy and will consume more if it’s turned up hotter. The fan and air con compressor pale into insignificance, really.

I assume the AC pump is 12V but it doesn’t really matter on a BEV whether it is or not - you’re still using the HV battery to power it.

 

[Mgkev]

@Chrispydoc , The fans are 12v, the A/C pump and heater are fed directly from the HV battery. I’m not sure yet if the heater heats water which is then fed to a heater matrix or heats the air directly. Talking of ICE efficiency, Toyota are proud of their 2.5L 4c engine because its claimed 40% efficient, I guess EVs are around 95%.

 

[Mgkev]

It’s more efficient to use HV directly rather to an convert to 12v as there wil be losses incurred during the process. Old traditional transformers loose around 5-10%.

 

[ging353]

In a word "YES"......more heat less range.

 

[Alan5]

I was having a play with my A/C and heating at the weekend , looking at the amp meter on the car which may not be that accurate the A/C has a very low draw on the battery , I think Bjorn Nyland said you could have the A/C on for over 40 hours with a full battery . I believe the Mgzsev has a PTC heater which is an efficient heater it will use more amps the higher you have the heat setting but I found fan speed is also the key having a lower fan speed means you can turn down the heat setting but still get a lot of heat output. You can also drive in eco mode have the car set to defrost with the fan speed turned down and get good heat from windscreen and side vents , it was also interesting to see that with the heater turned to cold and Aircon off there was no amp draw on the battery , which means although it reduces miles on the GOM with the HVAC on , in theory it's not using any HV battery power (apart from charging the 12volt ) and you could have the HVAC system running drawing air in from the outside to maybe reduce misting of the windows . More testing to do

 

[Mark Holmes]

"owt fer nowt" is the Yorkshire terminology, owt = anything, fer = for, nowt = nothing Chris.
Not sure if the MG has 12v AC or if it's a HV system, but on the Prius the AC electric pump is actually run off the 12v system so uses very little HV battery, heating is obviously off the ICE.
My guess for the MG would be HV heating and 12v fans and AC.

It would be nice to know one way or the other...

 

[Chrispydoc]

One of you clever blokes can get your measuring stuff out then. My electrical theory is even worse that my spelling!

 

[ging353]

We watch with interest.