Teslafi and pre-heating the car

[WannabeOwner]

Would the battery still have some residual warmth after 3 hours?

Doubtful. I reckon it can get cold parked up for an hour visting a client, in Winter.

Dunno if outside / inside temperature history in TeslaFi is any guide to how cold it was?

Either way, probably need more "data examples" to form a view

 

[vitesse]

3.0C yesterday outside and 3.5C this morning at time of departure. That half a degree might be it.

 

[LukeT]

I drop the Charge Limit by 10% for charging over night, and then raise it (and restart the charging) for hour-before-departure to try to heat the battery (and then heat cabin for 15 minutes before departure)

Dunno how much difference that makes. When I set off without doing that the time before Full Regen is available seems a lot longer. Bit subjective though.

The new/forthcoming update's "Precondition for departure time" rather than "Start charge AT" might do more?

I would be interested to see whether moving to say 30 or 45 mins heating the cabin makes a significant difference to you given your greater experience. Scheduled departure appeared to use this tactic.

 

[vitesse]

I would be interested to see whether moving to say 30 or 45 mins heating the cabin makes a significant difference to you given your greater experience. Scheduled departure appeared to use this tactic.

I'm only pre warming for 15-20 minutes to demist and make the cabin toasty for my missus. I can try 45 minutes tomorrow morning. But I do wonder if charging would be more effective than heating?

 

[LukeT]

I'm only pre warming for 15-20 minutes to demist and make the cabin toasty for my missus. I can try 45 minutes tomorrow morning. But I do wonder if charging would be more effective than heating?

Intuitively I thought charging the battery would warm the battery better than the otherwise only tangentially related operation of warming the cabin, however scheduled departure appears to me to take the opposite approach with good effect (gave me immediate full regen on a cold morning). Perhaps it's just that home charging battery temperature is nowhere near optimal driving battery temperature.

 

[vitesse]

Intuitively I thought charging the battery would warm the battery better than the otherwise only tangentially related operation of warming the cabin, however scheduled departure appears to me to take the opposite approach with good effect (gave me immediate full regen on a cold morning). Perhaps it's just that home charging battery temperature is nowhere near optimal driving battery temperature.

If you think about it 7kW sounds a lot until you realise it has to feed 4000-odd cells. Generating heat is not the primary objective of charging!

 

[NorfolkMustard]

If "scheduled departure" is doing similar to supercharger preconditioning, then it's separate from both cabin heating and charging

Intuitively I thought charging the battery would warm the battery better than the otherwise only tangentially related operation of warming the cabin, however scheduled departure appears to me to take the opposite approach with good effect (gave me immediate full regen on a cold morning). Perhaps it's just that home charging battery temperature is nowhere near optimal driving battery temperature.

I'm guessing ScheduledDeparture is doing more than we could do on our own. i.e. in addition to charging the batteries and heating the cabin, it's also doing what it does for Supercharger Preconditioning on the Model3 - heating coolant via the motor stator, and using that to heat the battery.

We need Bjørn to hook up his scanner for us

 

[vitesse]

If "scheduled departure" is doing similar to supercharger preconditioning, then it's separate from both cabin heating and charging


I'm guessing ScheduledDeparture is doing more than we could do on our own. i.e. in addition to charging the batteries and heating the cabin, it's also doing what it does for Supercharger Preconditioning on the Model3 - heating coolant via the motor stator, and using that to heat the battery.

We need Bjørn to hook up his scanner for us

Optimising the pack temperature surely has to be done by using the same heating system that warms the cabin? The pack temperature is regulated by liquid circulated by the climate control system - so it's cooled when it's hot and heated when it's cold. Fans supplement this when the pack gets particularly hot.

What's not clear to me is whether or not 'Conditioning' in Teslafi signals something fundamentally different to 'Heating'. Does running 7kW of cabin heating provide modest pack warming and does 'Heating' mean the power drawn is prioritised for heating the battery over the cabin? I know Musk has said that it may be better to use the seat warming and (if fitted) the steering wheel heating than the cabin heating.

Oddly, unlike some rival cars, Teslas don't use heat pumps, which seems inconsistent with Tesla's design sophistication.

 

[NorfolkMustard]

I thought (Model 3 specific perhaps?) :-

Cabin heater is a bog standard resistance heater, like a toaster, not liquid ?

Battery pack cooling/heating is done with liquid - cooled by radiator (+ fan when needed) and heated (in M3 at least) by dumping energy into the stator

 

[vitesse]

I thought (Model 3 specific perhaps?) :-

Cabin heater is a bog standard resistance heater, like a toaster, not liquid ?

Battery pack cooling/heating is done with liquid - cooled by radiator (+ fan when needed) and heated (in M3 at least) by dumping energy into the stator

You probably know more than me but yes, I understand the Model S (which I have) has a dedicated battery heater but the M3 doesn't.

 

[phillcom3]

Yeah, on each parking event there’s a separate calculation of kWh and range used by conditioning

Can you send me a teslafi code?

 

[NorfolkMustard]

Sent. Cheers

 

[vitesse]

This morning I pre-warmed the car for 41 minutes before my wife drove to work, instead of 20 minutes previously. The outside temperature was half a degree warmer (4C) but the roads were still wet from overnight rain - it was actually still slightly drizzling.

Instead of 500wH/mile, the consumption was 450wH/mile. There was still limited regen at the start of her drive. Average speed was the same on both days.

According to the smart meter the load started at 7kW but only stayed there briefly before dropping back to 3kW. The Teslafi 'battery heating' icon didn't come on.

It's very unscientific but let's say the pre-heating averaged 4kW over 41 minutes, that's about 2.7kWh.

If the car saved 50W per mile on a 15 mile journey, that's 750Wh

The cabin is warm enough after 10 minutes pre-warming so the extra 30 minutes isn't worth it in this example.