HVAC battery usage when plugged in

[peterjameswass]

Is it right that running the HVAC when the car is plugged in uses the battery as its power source?

I run my overnight charge with a scheduled start time of 12:30am controlled by the car (my home charge point is 'on' all the time). So normally the car reaches its 90% limit by early morning.

I then have a TeslaFi schedule to warm the car using the HVAC at around 8:15am so the car is nice and toasty when I leave for work.

I thought that the power for the HVAC would come from the home charge point but it seems to come (at least in part?) from the battery. For example, running the HVAC for 10 minutes this morning used up 2.56 miles of range -

Is that normal behaviour or am I doing something daft?

 

[MrBadger]

Ours comes from both - but we only do 10A charging so it won't pull the power it needs from only the mains.

 

[peterjameswass]

Yes...should have clarified that my home charge point runs at 32A.

 

[Big Earl]

It will pull as much from the mains as it can. On the Model 3 in cold weather, preconditioning runs the HVAC and battery heating, which total 13 kW at the start of the preconditioning session (the energy consumption drops as the cabin warms up and drops more as the battery warms up). As you know, the max AC input for the Model 3 is 11.5 kW, so the remainder is drawn from the battery pack.

On a 32 amp home charge point, about 7 kW is delivered from the wall and the remaining 6 kW will come from the battery.

I'm not sure which vehicle you're driving since this is posted in a regional forum (UK & Ireland) instead of the relevant model forum (Model S, 3, X Battery & Charging).

 

[Adopado]

Yes...should have clarified that my home charge point runs at 32A.

I should say that I have never noticed a loss of battery charge during any precondition of the car (also 32amp charge point). I don't have Teslafi stats I'm afraid. Did you actually see the loss on the battery percentage in the car with on screen or via the app?

 

[MrBadger]

0.58kWh is less than 1% on a LR and around 1% on an SR.

 

[peterjameswass]

To answer the questions raised...car is a Model 3 Performance...and yes, the range loss shown on TeslaFi is also reflected in the percentage shown in the car.

In terms of battery preconditioning, how long would you have to run the HVAC (let's say in ambient temperatures of 5C or thereabouts) to see any effect on the availability of regen for example? I warm the car for around 15 mins which is plenty to get the cabin warm but I usually still get the 'regen reduced' message and a fair few dots on the left of the power indicator strip.

 

[Jeeves]

Depends on outside temperature. Bjørn Nyland has several videos on this. 30 mins should do it unless it is < -12°C.

 

[Adopado]

I warm the car for around 15 mins which is plenty to get the cabin warm but I usually still get the 'regen reduced' message and a fair few dots on the left of the power indicator strip.

I also tend to regard 15 minutes to be the sweet spot. It doesn't remove all the restricted regen dots but it makes a notable difference. If the car has been unused for 24hrs+ and/or temperatures are getting well below freezing then a longer period could be worthwhile.