Parking outside in very cold weather and not plugged in

[Cottonwood]

I wonder what a webasto circulating coolant heater would do retrofitted to the battery coolant loop....

Try to find a place to tap into it that will be effective...here is the coolant loop diagram from a maintenance screen:

We believe that the valve on the left can go to "series" mode from "parallel" mode to put the inverter/motor into the loop and help heat the battery. Note that this also puts the liquid cooling of the AC chargers in a place where their waste heat can help heat the batteries. If we assume 90% AC to DC conversion, that is almost 1 kW waste heat 40 Amp charging and almost 2 kW waste heat from 80 Amp charging to heat the batteries. This is a good reason to have your charging finish just before departure on cold days and also a good reason for dual chargers and 80 Amp charging at home if you live in a cold climate.

 

[taurusking]

@cottonwood: Thanks for posting the picture and providing a response. I have read some of your posts on charging and you have gone beyond and far in explaining things...

You should write a manual for us Tesla owners :biggrin:

 

[svp6]

Since we had sub-0 temps in sunny Minnesota, and my working place garage is open I can also chime in. Over 10 hours I saw ~10-20 miles drop in range (range mode off, always connected on - it did not matter to me if I lost even more range). The not so nice experiences were:

1. On the coldest day (-8F=-22C when I had to leave) the car would not communicate with the Tesla app, which kept saying "waking up the car". That made for a cold drive home that evening - not happy. The car started normally when I arrived in the garage, had the blue flake next to the battery.
2. The consumption (without range mode on) at those temps is horrendous. Highest I have seen was ~1.7 kwh/mi - and we are talking here 20-50 mph speed. This is for short distance though.

 

[ThosEM]

I wonder what a webasto circulating coolant heater would do retrofitted to the battery coolant loop....

That's exactly what some folks with iMiEVs are installing: http://insideevs.com/video-utilizing-a-combustion-heater-in-a-fully-electric-car-an-users-story/

- - - Updated - - -

Since we had sub-0 temps in sunny Minnesota, and my working place garage is open I can also chime in. Over 10 hours I saw ~10-20 miles drop in range (range mode off, always connected on - it did not matter to me if I lost even more range). The not so nice experiences were:

1. On the coldest day (-8F=-22C when I had to leave) the car would not communicate with the Tesla app, which kept saying "waking up the car". That made for a cold drive home that evening - not happy. The car started normally when I arrived in the garage, had the blue flake next to the battery.
2. The consumption (without range mode on) at those temps is horrendous. Highest I have seen was ~1.7 kwh/mi - and we are talking here 20-50 mph speed. This is for short distance though.

From what I see in moderate Maryland, I can well imagine that things get very dicey below 0F. I can't figure out why we don't hear more about that from all those Norwegians with Model S. And it just seems obligatory to me for any EV used in an arctic climate to have a combustion heater to preserve its electric range. I can make a pretty good case that it is just as bad to heat a car with electric resistance heat as it is to move a car with an internal combustion engine. And there are some fuels available (biogas, biodiesel) that are arguably carbon neutral. So why not use them?

 

[jpet]

We believe that the valve on the left can go to "series" mode from "parallel" mode to put the inverter/motor into the loop and help heat the battery.

That is indeed the case. Here is an example:

 

[Cottonwood]

That is indeed the case. Here is an example:

Thanks for the example of "Parallel" mode. Of course, this looks like a light cooling example with temps around the loop about 30˚ C, 86˚ F.

 

[max35111]

Guys, just to let you know the actual figures for the weekend:
- temperature or -2 celcius during the day and -10 during the nigh.
- first day: loss of 20km
- second day: loss of 10km
- warming up the car: loss of 12km

And a weird surprise: the place where the front camera is was snow-free... See pic

 

[Cottonwood]

Guys, just to let you know the actual figures for the weekend:
- temperature or -2 celcius during the day and -10 during the nigh.
- first day: loss of 20km
- second day: loss of 10km
- warming up the car: loss of 12km

And a weird surprise: the place where the front camera is was snow-free... See pic

Thanks for the detailed numbers.

So the Tesla wants to keep and eye on things while waiting. :biggrin: I guess that is a nice, little secondary defroster for the camera, as well...

 

[jpet]

So the Tesla wants to keep and eye on things while waiting. :biggrin: I guess that is a nice, little secondary defroster for the camera, as well...

That's indeed quite interesting. Isn't an infrared beam used to detect rain on the windshield? But I assume the area would be much smaller if it's only that sensor.

 

[green1]

And a weird surprise: the place where the front camera is was snow-free...

That's... odd... There is a small defroster wire in the windshield in that location, but I've always assumed that it was only on when the car thought it was needed while driving, I'm a little concerned to see that it was on while parked and obviously for quite some time if it either prevented snow buildup in that location, or managed to clear it there.

 

[hybridbear]

1. On the coldest day (-8F=-22C when I had to leave) the car would not communicate with the Tesla app, which kept saying "waking up the car". That made for a cold drive home that evening - not happy. The car started normally when I arrived in the garage, had the blue flake next to the battery.

Is this a common occurrence with the Model S when temps get that cold? We've had this on occasion with our Ford plug-ins on the coldest days, but usually they don't lose their connection until the air temp is at least -10 F or colder. And, even at those temps it is unusual. Opening their app every hour or two will keep them connected, even on the coldest days. I would hate to not have preconditioning.

 

[DCGOO]

Is this a common occurrence with the Model S when temps get that cold? We've had this on occasion with our Ford plug-ins on the coldest days, but usually they don't lose their connection until the air temp is at least -10 F or colder. And, even at those temps it is unusual. Opening their app every hour or two will keep them connected, even on the coldest days. I would hate to not have preconditioning.

No, it is not. I have always been able to turn on the heat. TBH, it has not been to -10 here yet. Going to -2ºF tonight.

 

[green1]

Is this a common occurrence with the Model S when temps get that cold? We've had this on occasion with our Ford plug-ins on the coldest days, but usually they don't lose their connection until the air temp is at least -10 F or colder. And, even at those temps it is unusual. Opening their app every hour or two will keep them connected, even on the coldest days. I would hate to not have preconditioning.

I would bet the no communication thing had zero to do with the temperature, and was just one of those things that the app does intermittently. I've never had a problem, and yes, I have used it after the car sat all night outdoors at -23c

 

[Andyw2100]

Could someone please explain the significance of the passive cooling target, the active cooling target, and the active heating target?

I'm very interested in how, if at all, this relates to battery temperature, preheating, and the regenerative braking limit.

Thanks!

 

[Cottonwood]

Could someone please explain the significance of the passive cooling target, the active cooling target, and the active heating target?

I'm very interested in how, if at all, this relates to battery temperature, preheating, and the regenerative braking limit.

Thanks!

My understanding is the following:

• Passive Cooling — Using the "radiator" to get rid of heat by putting it into the surrounding air without using the heat pump.
• Active Cooling — Using the heat pump (similar to an air conditioner) to actively pump heat from the batteries into the surrounding air.
• Active Heating — Using the resistive heater to warm the battery using energy from the battery or shore power, if available.

What is not mentioned is what I will call "Passive Heating." Using the diagram, it is certainly possible to use waste heat from the Inverter/Motor and the AC Charger(s) to warm up the batteries. I propose that the Tesla engineers have included this mode. For example, with 80 Amp AC charging, there is almost 2 kW available in "waste heat" from the Chargers that could be used to warm the battery.

See Reading Battery Voltages and Temperatures via CAN on Model S. I have one of these on order, and I recommend that others interested in the details of winter battery warming order one as well. By looking at the details of the battery temperature during charging, we can better understand how the battery thermal management works.

 

[green1]

I propose that the Tesla engineers have included this mode. For example, with 80 Amp AC charging, there is almost 2 kW available in "waste heat" from the Chargers that could be used to warm the battery.

Tesla has stated they use waste heat from the motor and inverter to warm the pack, but I have never heard anything to indicate they are able to use waste heat from the chargers, also keep in mind that not all of that waste is within the chargers, some is in the wiring and/or EVSE.

 

[Cottonwood]

Tesla has stated they use waste heat from the motor and inverter to warm the pack, but I have never heard anything to indicate they are able to use waste heat from the chargers, also keep in mind that not all of that waste is within the chargers, some is in the wiring and/or EVSE.

The motor/inverter waste heat is available while driving and the charger(s) waste heat is available while charging. Both the motor/inverter and charger(s) are in the same cooling loop. It would only make sense to use the charger heat to warm the battery while charging, but we have not confirmed that process. It would be a real shame if Tesla did not use the charger waste heat...

Although there is some waste heat in the EVSE and the wiring, the vast majority is in the charger itself. Look at some 80 Amp numbers:

1. 2*50' or 100' (30 meters) of #3 copper wire at 80 Amps — 80A[SUP]2[/SUP] * 0.1*0.197Ohm/1000' = 0.13 kW
2. 90% efficient charger, 10% waste heat — 240V * 80A * 10% = 1.92 kW

As you can see comparing 1.92 kW to 0.13 kW, the waste heat from the charger overwhelms the heat in the wiring. The waste heat in the EVSE should be comparable or less than the wiring. After all, it's just a big GFCI with a couple more safety interlocks.

 

[dabbler]

It was -7 F. last night with -20 F wind-chill temps here is SE Wisconsin. I am planning to charge outside with a dual charger set up and the HPWC for a few hours, about 5 hrs. Then move my MS to a garage (out of the wind) and plug into 110V to keep the battery warm.

As an option to the above, does it make sense to park my MS over two layers of pink sheet foam insulation, lower it down on the insulation with the air suspension during the fast charge to assist maintaining heat in the battery while remaining outside for the night?

 

[Andyw2100]

My understanding is the following:

• Passive Cooling — Using the "radiator" to get rid of heat by putting it into the surrounding air without using the heat pump.
• Active Cooling — Using the heat pump (similar to an air conditioner) to actively pump heat from the batteries into the surrounding air.
• Active Heating — Using the resistive heater to warm the battery using energy from the battery or shore power, if available.

Thanks for the response, Cottonwood.

So focusing just on the Active heating for the moment, what happens above and below the target of 8 C? Does the target of 8 C mean that if the pack falls below that temperature, the resistive heater will be used to keep it at the target temperature, so in theory our pack temperature should never fall below 8 C?

Thanks!

 

[Cottonwood]

[/LIST]
Thanks for the response, Cottonwood.

So focusing just on the Active heating for the moment, what happens above and below the target of 8 C? Does the target of 8 C mean that if the pack falls below that temperature, the resistive heater will be used to keep it at the target temperature, so in theory our pack temperature should never fall below 8 C?

Thanks!

The answer is not quite so simple, and depends on the state of the Model S and its settings.

Please understand that the following answers are my best guesses based on intelligent observations by me and others on TMC and what I would propose are good engineering practices.

Here are a few cases and what I think is (should be) happening:

1. Car Driving, Range Mode Off, Battery Temp Below 8˚C. — This is the case where it seems most likely the resistive heater is warming the battery.
2. Car Driving, Range Mode On, Battery Temp Below 8˚C. — Here, the heatlng is either less or the active threshold is lowered.
3. Car Off, Not Plugged In, Battery Temp Below 8˚C. — Many have observed that the car does not use the battery and resistive heater to warm the battery in this case. This would drain the battery pretty quickly.
4. Higher Powered AC Charging Active, Range Mode Off, Battery Temp Below 8˚ C. — The Model S does use the resistive heater to warm the battery.
5. Lower Powered AC Charging Active, Range Mode Off, Battery Temp Below 8˚ C. — This is a question mark. Several have observed no net charging at low temps, implying that the resistive battery is active.

This is a complicated subject with many cases, but one thing is for sure: If the car is sitting in the cold, off, and not connected to any power, the battery will get much colder than 8˚C.