Battery Heating May Have Changed

[hybridbear]

Last night after my car cold soaked during the Super Bowl party for 7 hours the pack was cold enough to need the heater. I had put the car in range mode before arriving so that I could see how it behaved. The API data in TeslaFi shows that the pack heater didn't turn on until I turned off range mode. This matches what I observed for power draw when stopped and looking at the dash power meter. It appears the API data is correct for when the pack heater is active.

 

[David29]

The pack heater comes on when you preheat from the remote app, period. Regardless of whether shore power is present or not. It has always worked this way and still does.

I don't need an app to tell me this. Simple observation - I live in a place that routinely sees -20C weather (or colder).

With a cold-soaked battery I will have no regen.

In the same conditions, if I preheat (shore power or not) I will have 50% regen.

I see this all the time.

So why would the Owner's Manual say it only comes on if you are plugged in? Do you suppose Tesla is trying to encourage people to plug in to avoid drawing the battery too low?

 

[JasonA-EV]

I've never seen the pack heater come on with or without range mode when using the Tesla app and NOT PLUGGED in. Now this is on my 70D watching both the CAN data, pack temps, etc...

If the pack is cold (any temp, whatever) I can remotely kick in the interior climate control and make it nice and toasty and run that thing for hrs and hrs and pack will stay STONE COLD. and not rise up ONE single degree.

If the car is plugged in, then the pack will slowly rise up but not that fast. Took 1 hr to go from 48* to 61*. There's alot of thermal mass to increase!

 

[Andyw2100]

Last night after my car cold soaked during the Super Bowl party for 7 hours the pack was cold enough to need the heater. I had put the car in range mode before arriving so that I could see how it behaved. The API data in TeslaFi shows that the pack heater didn't turn on until I turned off range mode. This matches what I observed for power draw when stopped and looking at the dash power meter. It appears the API data is correct for when the pack heater is active.

So that would seem to indicate that the field / API worked --for you--. It is definitely not working that way for many of us.

 

[hybridbear]

So that would seem to indicate that the field / API worked --for you--. It is definitely not working that way for many of us.

How cold has your HVB been? Have you seen the power draw on the dash from the pack heater but the API data saying "false"?

 

[AWDtsla]

It has long been the common belief here on TMC that if one preheated the cabin, while on shore power, with range mode off, the battery pack would also be heated, provided the pack was cold. (if the pack had been charging, it may not have been cold.)

I think there is a chance that this behavior has recently changed. I am saying that because of some posts in another thread. Here is one of the relevant posts:

TeslaFi.com

Basically using TeslaFi, we can see when our battery heater is on. And it appears it may not be turning on when preheating the cabin.

Additionally, it seems that the battery heater may not come on 100% of the time the battery is cold and a drive is started with range mode off. The common belief here had always been that the battery heater DID come on in this situation, which was one of the reasons wh/mi numbers are quite high during short, cold drives.

It would be great if others with the ability to monitor the battery heater weighed in on this.

Thanks!

Just tried this. It is Teslafi.com (or the API call) that is wrong. My pack heater was clearly on during preheating.

 

[Doug_G]

So why would the Owner's Manual say it only comes on if you are plugged in? Do you suppose Tesla is trying to encourage people to plug in to avoid drawing the battery too low?

I suppose it's possible things have changed with one of the software updates. It definitely preheated unplugged before.

There really hasn't been a lot of uber-cold weather this year. I'll repeat my experiment at the next opportunity.

 

[AWDtsla]

There really hasn't been a lot of uber-cold weather this year. I'll repeat my experiment at the next opportunity.

Pack only has to be under 50F to turn on the pack heater. It's not that hard.

 

[Doug_G]

Sure, but I'm not looking at data bits that may or may not be interpreted correctly. I'm looking at the impact on regen availability.

 

[AWDtsla]

Sure, but I'm not looking at data bits that may or may not be interpreted correctly. I'm looking at the impact on regen availability.

Just look at consumption when stopped. ~5.5kW fixed load in addition to anything else. i.e. You'll go from 6-11kW draw if you're preheating the cabin too. No other way to draw that much power standing still.

 

[ArtInCT]

Each morning I activate climate via my iPhone app and start the heater to 68F. Recently the unheated garage temperature has been averaging in the high 20F range when the climate was invoked. My S is always plugged in to the HPWC.

I am a long time TeslaFi user.

I can see the TeslaFi raw data and at NO TIME does the "Battery Heater ON" field indicate TRUE while the climate was on.

However, once I am on the road, for my first trip of the day, I do notice the TeslaFi data shows TRUE for about 6 to 11 minutes regarding the Battery Heater On field if the temperatures are cold.

Thought I would just throw this out there with my observations.....

Note: on my first trip of the day in the cold winter weather, my cabin heater, heated steering wheel AND my seat heater are ON.

Does State of Charge have anything to do with Battery Heater On use by the S?

BTW, I am on 2.52.22

 

[Doug_G]

Just look at consumption when stopped. ~5.5kW fixed load in addition to anything else. i.e. You'll go from 6-11kW draw if you're preheating the cabin too. No other way to draw that much power standing still.

Both heaters are variable power. I only get 11 kW if it's stone cold.

 

[Kalud]

Each morning I activate climate via my iPhone app and start the heater to 68F. Recently the unheated garage temperature has been averaging in the high 20F range when the climate was invoked. My S is always plugged in to the HPWC.

I am a long time TeslaFi user.

I can see the TeslaFi raw data and at NO TIME does the "Battery Heater ON" field indicate TRUE while the climate was on.

However, once I am on the road, for my first trip of the day, I do notice the TeslaFi data shows TRUE for about 6 to 11 minutes regarding the Battery Heater On field if the temperatures are cold.

Thought I would just throw this out there with my observations.....

Note: on my first trip of the day in the cold winter weather, my cabin heater, heated steering wheel AND my seat heater are ON.

Does State of Charge have anything to do with Battery Heater On use by the S?

BTW, I am on 2.52.22

The battery heater flag (from the API) does not turn on when the car is no driving. Still the battery heater always turns on when preconditioning (or driving) when the pack is bellow 8C in normal mode (-10C in range mode). Those are the active heat target. It does that plugged in or not plugged in. Those targets are valid for normal >50% SOC. Its get progressively more aggressive (targets raises) as SOC go down. That's why, even in range mode in cold temperature, at low SOC (like less than 10%) the pack heater turns on with a target around 15C or more.

Once you start to drive, the API Pack heater flag turns to true if its (still) heating.

So, while parked (drive rail off), the API pack heater flag is ALWAYS false regardless of pack heater status.

 

[AWDtsla]

Both heaters are variable power. I only get 11 kW if it's stone cold.

Evidence? I've never seen the pack heater consume less that 5.5kW. Nor is there ever any reason to do so. It's enormously undersized. Max battery heating is usually well over an hour any time in the winter.

edit - and you can see the electronics pack mounted on the heater core to regulate power output, but the pack heater has nothing on it except HV leads.

 

[Doug_G]

I'm talking about the combined draw of the pack heater and cabin heat. I can only see the combined current.

 

[AWDtsla]

I'm talking about the combined draw of the pack heater and cabin heat. I can only see the combined current.

There's only a 1kW range where there is ambiguity about if just the cabin heater is at full power or it's at 1kW with the pack heater on. 99% of the time it's pretty unambiguous.

 

[Doug_G]

Okay so today was -8C to -10C. Not super cold but after 8 hours the car would have had little or no regen available.

I preheated via remote app for 20 minutes, with the car unplugged. I had just shy of 50% regen (approx. 28kW) available upon startup.

Last week the car sat at -10C all day, I did not preheat, and it had no regen.

I think it's pretty clear that it still preheats the battery pack regardless of whether it is plugged or not.

 

[ram1901]

If battery is colder than X (unknown value (?17F)) it will preheat prior to charging.
If battery is colder than X (unknown value(?17F)) while driving there will be little to no regen as it preheats.
If battery is colder than X (unknown value(?17F)) and car is plugged in it will use shore power to pre heat before charging.
If battery is colder than X (unknown value(?17F)) and car is moving it will use battery power to pre heat before providing regen.
If battery is warmer than X (unknown value) pre heat will not be necessary and regen will be available at some level.
That's my story and I'm stickin' to it..

 

[Kalud]

Fixed:

If battery is colder than 32F it will preheat prior to charging. (Can't charge bellow 32F. Heat target depends on charging power, about 34F for 115V 12A to about 25C and more to SuperCharge)
If battery is colder than 32F while driving there will be little to no regen as it preheats. (same as above, no charging = no regen as its the same)
If battery is colder than 32F and car is plugged in it will use shore power to pre heat before charging.
If battery is colder than 46F (non range mode) or 14F (range mode) and car is moving it will use battery power to pre heat before providing regen.
If battery is warmer than 46F (non range mode) or 14F (range mode) pre heat will not be necessary and regen will be available at some level.
added: If battery is colder than 46F (non range mode) or 14F (range mode) and car is parked, starting cabin preconditioning will use battery power (or shore power if available) to pre heat pack.
That's my story and I'm stickin' to it..

All those true for SOC > 50% approx. Bellow that, all targets increase progressively.

Also nice thing to know. If plugged in outside in the cold, it will start charging every 24h and thus, pre-heat the pack if bellow 32F (can't charge bellow 32F). So pack will always be somewhat warmer than ambient, unless its SUPER cold and it drops to ambiant in less than 24h. But regardless, it will re-heats it up to above 32F then charge, then wait 24h.

 

[Doug_G]

-14C, unplugged, total draw 10.64 kW.