HVAC Energy usage

[JodyS21]

I've been trying to figure out the "exact" energy usage of the various HVAC etc functions, discovered a couple of anomalies.

This was all done today at -2c with the car in Ready and nothing else on, journey & accumulated trips reset, voltage was reading 413v. I just thought, I'm pretty sure the mode was in E still (I really should've made certain).

Rear heated window - uses 1Amp
Heated seats (1or2) - uses 0Amps
Air re-circulate on/off - no difference
Max heat temperature & Fan on 6of6 - uses 1-6Amps(constantly flickers between)
Max heat temperature & Fan on 6of6 & Air Con on - uses 1-6Amps(constantly flickers between)
Now here's the anomaly:
Pressing the Front window demist button - This switches Air Con ON / Directs air to window only / Sets Fan to 5of6 / Turns Rear window heater ON / Air-recirculate is Off.
If I MANUALLY set all of the above - it uses 1-6Amps
If I PRESS the Front window demist button - it uses an ADDITIONAL 10Amps - I cannot hear/identify any difference.

Also regarding the GOM with the above....
MANUALLY setting any of the HVAC/heated window&seats etc on, does not change the GOM.
PRESS the Front window demise button (with the exact same settings as done manually, reduces the GOM by about 10%.

(FYI: at 413Volts, 10Amps is 4.13kWh)

Thoughts/comments????

 

[Nibloprice]

Sounds like the sequence in Apollo 13 where they have to turn on the spacecraft in the right order in order not crash into the planet at full speed...Hope I don't press the wrong button...

 

[macd2401]

I'm sure a few folks have suggested that in eco mode, the heater doesn't feel as warm. Just wondering if the test figures in eco mode are overridden by the auto demist function (the heater maybe having certain levels in different modes)

 

[rbpasapera]

I've been trying to figure out the "exact" energy usage of the various HVAC etc functions, discovered a couple of anomalies.

This was all done today at -2c with the car in Ready and nothing else on, journey & accumulated trips reset, voltage was reading 413v. I just thought, I'm pretty sure the mode was in E still (I really should've made certain).

Rear heated window - uses 1Amp
Heated seats (1or2) - uses 0Amps
Air re-circulate on/off - no difference
Max heat temperature & Fan on 6of6 - uses 1-6Amps(constantly flickers between)
Max heat temperature & Fan on 6of6 & Air Con on - uses 1-6Amps(constantly flickers between)
Now here's the anomaly:
Pressing the Front window demist button - This switches Air Con ON / Directs air to window only / Sets Fan to 5of6 / Turns Rear window heater ON / Air-recirculate is Off.
If I MANUALLY set all of the above - it uses 1-6Amps
If I PRESS the Front window demist button - it uses an ADDITIONAL 10Amps - I cannot hear/identify any difference.

Also regarding the GOM with the above....
MANUALLY setting any of the HVAC/heated window&seats etc on, does not change the GOM.
PRESS the Front window demise button (with the exact same settings as done manually, reduces the GOM by about 10%.

(FYI: at 413Volts, 10Amps is 4.13kWh)

Thoughts/comments????

Nice and useful data. Hope this doesn't sound rude, but volts * amps = KW (power), KWh is for energy.

 

[JodyS21]

Quick update.
Did it again this afternoon after using the car again (so it was "warmed" up)

In ECO mode, pressing the Front window demist button VS all the same settings manually, causes the ~10Amps difference.
In Normal or Sports mode, manually using these settings, causes the higher Amp figure.

One can therefore assume, given the sound doesn't change; that in ECO mode, without the button pressed, the heater probably just doesn't get given full power.


If you want to eek out the range, using ECO mode, if you need heating, just select any/all of the settings manually - do not use the [Front window demist] button. This will ensure you're not using the additional ~4kW, which is ~10% of the cars battery capacity every hour it's on.

 

[Kithmo]

I'm sure a few folks have suggested that in eco mode, the heater doesn't feel as warm. Just wondering if the test figures in eco mode are overridden by the auto demist function (the heater maybe having certain levels in different modes)

In normal mode, mine doesn't show any increase in the heat setting when demist is switched on just an increase in fan speed. So I have to bump up the heat manually, with demist on, first thing to speed up the defrost process then when I turn demist off I have to turn the heat back down to my usual 3 blobs.

 

[JodyS21]

Just for clarification purposes:
Pressing the Front window demist button Does Not change the cold/heat setting. It will be on whatever you had left it on.
BUT if you have the temp turned on hot (as I did), I think the extra 10Amps must be it allowing more juice to the heater (only does this in eco mode).

 

[Lovemyev]

The blower fan in the HVAC unit is powered directly from the 12 volts battery is my view.
In Eco mode the heat supplied to the cabin is reduced in an attempt to save power being drawn rom the HV battery.
The bigger demand for heat, the more range is lost from GOM ( predicted range ) instantly.
Try this, as you boot up the car ( normal and regen level 3 ) make sure the HVAC is fully turned off.
Keep an eye on the GOM and turn on the heater blower to number 1, but make sure there is NO demand for heat set on the HEAT control.
Increase the speed on the blower motor, click by click.
The impact on the range will be almost nothing because the power used by the heater blower motor is very small.
Now, leave the blower switch on say....... number 3.
As you start to increase the demand for heat ( on the heat control ) watch how the GOM reacts as the switch is increased higher and higher to provide heat to the cabin.
By the time you have reached MAX heat, you will have witnessed a huge loss in range as a result of the increase in demand for heat, easy to loose 30 miles from the GOM very quickly.
More heat, means less range - pure and simple I am afraid, that is the trade off.
That is why a lot of EV owners like the heated seat option.
The effect of running the heated seats is almost nothing, compared to the cabin heater.
Another big winner, is being able to preheat the car when it is still plugged in to the wall box.
It will draw power from the wall box to provide power to the heater, without affecting the range.
A heat pump would help, but these are an expensive option that not all EV's have.
The heat pump option on a Golf was over £1,000.
I believe Tesla are now fitting heat pumps to the latest model 3's as standard equipment now.

 

[JodyS21]

The blower fan in the HVAC unit is powered directly from the 12 volts battery is my view.
In Eco mode the heat supplied to the cabin is reduced in an attempt to save power being drawn rom the HV battery.
The bigger demand for heat, the more range is lost from GOM ( predicted range ) instantly.
Try this, as you boot up the car ( normal and regen level 3 ) make sure the HVAC is fully turned off.
Keep an eye on the GOM and turn on the heater blower to number 1, but make sure there is NO demand for heat set on the HEAT control.
Increase the speed on the blower motor, click by click.
The impact on the range will be almost nothing because the power used by the heater blower motor is very small.
Now, leave the blower switch on say....... number 3.
As you start to increase the demand for heat ( on the heat control ) watch how the GOM reacts as the switch is increased higher and higher to provide heat to the cabin.
By the time you have reached MAX heat, you will have witnessed a huge loss in range as a result of the increase in demand for heat, easy to loose 30 miles from the GOM very quickly.
More heat, means less range - pure and simple I am afraid, that is the trade off.
That is why a lot of EV owners like the heated seat option.
The effect of running the heated seats is almost nothing, compared to the cabin heater.
Another big winner, is being able to preheat the car when it is still plugged in to the wall box.
It will draw power from the wall box to provide power to the heater, without affecting the range.
A heat pump would help, but these are an expensive option that not all EV's have.
The heat pump option on a Golf was over £1,000.
I believe Tesla are now fitting heat pumps to the latest model 3's as standard equipment now.

That makes sense, I'm going to hazard a guess that everything is powered by the 12v battery except for the heater.
It's all adding up! Everything is probably standard car parts - running at 12v, except for the heater which isn't standard/required on an ICE car and requires lots of power so is running from the HV battery...

 

[Lovemyev]

That makes sense, I'm going to hazard a guess that everything is powered by the 12v battery except for the heater.
It's all adding up! Everything is probably standard car parts - running at 12v, except for the heater which isn't standard/required on an ICE car and requires lots of power so is running from the HV battery...

Yep - That's pretty much the size of it !.

 

[Jeps]

Today on my 140 km (2x70) trip I tried to use the ECO mode on the first leg and on the home leg I used Normal. I noticed the N mode gave me a better heating, that was needed because the temperature was around -5 degrees today. I used more energy in Eco mode but that was due to headwind. In winter time I estimate the range to drop 25-30%. That is on par with our previous EV( Peugeot iOn)