Getting limited regen even after 1 hour of preheating, is it normal?

[hroussel]

I just got my S75D last week, in the coldest temps so far in Montreal this winter.

I read about limited regen and experienced it, but I thought that by sufficiently preheating the car I would get full regen capability. But even with 1 hour of preheating I'm at about 30kw max regen.

So the question is: is it possible to get full regen with preheating alone? BTW the temps I'm talking about are like -17C (1F).

 

[S100D]

I just got my S75D last week, in the coldest temps so far in Montreal this winter.

I read about limited regen and experienced it, but I thought that by sufficiently preheating the car I would get full regen capability. But even with 1 hour of preheating I'm at about 30kw max regen.

So the question is: is it possible to get full regen with preheating alone? BTW the temps I'm talking about are like -17C (1F).

If Range Mode is turned on, turn it off to see if this helps. Range Mode decreases the amps to the battery heater. It is ok to turn on when driving, but in the winter, it is recommended to turn it off when charging.

Most people forget to turn it off when parking the car. It is a shame that Tesla cannot change the code to do this automatically.

 

[TMeister]

I've let the car cold soak to 20F and found that gets me 0 kW regen. Preheating for 20 minutes only dents that a little, maybe to 20 kW. The most economical way I believe to get your regen back is to drive the car. At 30F driving about 20 miles removes the regen limitation.

 

[MocosMan]

The other way to get better regen is to time the night time charge so that it finishes right when you are due to start your trip. I find that about 3 hours of charge time will bring most or all of the regen back. But then when I park at work without charging I drive home with limited regen.

It will be great when Tesla pushes an update that allows more advanced scheduled charging like the Volt has. As it is I have to due the brief math when I park the car at night to figure out what time to start charging.

 

[hroussel]

The other way to get better regen is to time the night time charge so that it finishes right when you are due to start your trip. I find that about 3 hours of charge time will bring most or all of the regen back. But then when I park at work without charging I drive home with limited regen.

It will be great when Tesla pushes an update that allows more advanced scheduled charging like the Volt has. As it is I have to due the brief math when I park the car at night to figure out what time to start charging.

If Range Mode is turned on, turn it off to see if this helps. Range Mode decreases the amps to the battery heater. It is ok to turn on when driving, but in the winter, it is recommended to turn it off when charging.

Most people forget to turn it off when parking the car. It is a shame that Tesla cannot change the code to do this automatically.

Range mode is already off.

I guess I'll have to do some tests on length of preheating time vs how much regen back.

 

[hroussel]

The other way to get better regen is to time the night time charge so that it finishes right when you are due to start your trip. I find that about 3 hours of charge time will bring most or all of the regen back. But then when I park at work without charging I drive home with limited regen.

It will be great when Tesla pushes an update that allows more advanced scheduled charging like the Volt has. As it is I have to due the brief math when I park the car at night to figure out what time to start charging.

OK so at least it's possible to set a starting time for charging? I have to check for that (still discovering the car). Doing the math is fairly simple.

 

[jdw]

The word is, or used to be, that turning on the climate while plugged in would also turn on the battery heater. Based on what Teslafi reports for battery heater status, it does not. According to Teslafi, the battery heater comes on when you put the car in drive, but it may also be that the state of the battery heater doesn't report to the API until you put the car in drive. My own experience says that any benefit of preheating the car is mostly limited to heating the cabin, at least in the shorter times I use it.

Having charging complete shortly before departure remains the best way to eliminate regen limiting. Range mode does limit both battery and cabin heating and is especially useful on multiple short trips in the winter.

 

[Doug_G]

Preheating via app definitely DOES heat the pack. Half hour preheat at -20C is the difference between zero regen and 1/2 regen power.

It only ever heats enough to give you 1/2 regen though. Additional time does nada.

 

[jdw]

Good news - Electrek this morning

 

[josher32]

Good news - Electrek this morning

This is great news and something I had hoped Tesla would add for us cold climate folks for awhile. What would be ideal is for the car to auto turn on battery heaters for a scheduled departure time so we can have full regen from start in cold temps.

 

[gavine]

This is great news and something I had hoped Tesla would add for us cold climate folks for awhile. What would be ideal is for the car to auto turn on battery heaters for a scheduled departure time so we can have full regen from start in cold temps.

And you wouldn't necessarily need to pre-heat the cabin because the heater will use the warmth from the battery to heat the cabin once you turn it on. I don't believe in pre-heating the cabin because the electric heater heats-up very quickly and the pre-heating in the cabin mostly escapes once you open the doors, especially falcon wings. A waste of energy in my opinion, but not a waste when you directly heat the battery and regain most if not all+ of that energy with full regen being available. Looking forward to this new app update.

 

[MP3Mike]

And you wouldn't necessarily need to pre-heat the cabin because the heater will use the warmth from the battery to heat the cabin once you turn it on.

No, they do not use the heat from the battery/inverter/motor to heat the cabin. They are separate coolant loops.

the pre-heating in the cabin mostly escapes once you open the doors

Sure the pre-heated air escapes quickly, but the point is to pre-heat the actual mass inside the car, so that once you close the door the air comes back up to temperature more quickly and you don't have to sit on/hold something that is frozen.

 

[hroussel]

Preheating via app definitely DOES heat the pack. Half hour preheat at -20C is the difference between zero regen and 1/2 regen power.

It only ever heats enough to give you 1/2 regen though. Additional time does nada.

Thanks, that seems to confirm my observations for the last couple of days.

I also noticed the other day, after having parked for a full day (8hours) inside a heated garage at 12C (54F), that regen was still limited to roughly 30kw. I guess one really needs 20C (68F) and above to get immediately full regen?

 

[SMAlset]

We're in SFBay area so no where near as cold as you OP and this is our first year with car too. Oct 12 hubby first noticed the regen limit pop up and we weren't even near freezing then.

Great heads up on the winter battery update in the works. The tech can be what gives you headaches (as with anything with it in it) but really nice when they can give you features or extra power on your car at ofher times.

 

[gavine]

No, they do not use the heat from the battery/inverter/motor to heat the cabin. They are separate coolant loops.

Thanks for the correction. I’m very surprised and disappointed by this.

 

[N..8]

Preheating via app definitely DOES heat the pack. Half hour preheat at -20C is the difference between zero regen and 1/2 regen power.

It only ever heats enough to give you 1/2 regen though. Additional time does nada.

Doug, Do you think that doing this is actually heating the pack or just passively heating it due to the drain on the battery pack from the cabin heater being used.

 

[Nick B]

Thanks, that seems to confirm my observations for the last couple of days.

I also noticed the other day, after having parked for a full day (8hours) inside a heated garage at 12C (54F), that regen was still limited to roughly 30kw. I guess one really needs 20C (68F) and above to get immediately full regen?

I also heat my garage to 10 celcius and start off with usually half the regeneration. I've toyed with the heating and you really need 18-20 for full regeneration which, in my mind, is not really energy efficient (heating the garage to 18 that is). Also, if you have half the regeneration available, the car does not behave very differently from a fully available 100% regeneration. The real challenge, I find, is starting with zero regeneration which makes the car a little scary to drive!

 

[Doug_G]

Doug, Do you think that doing this is actually heating the pack or just passively heating it due to the drain on the battery pack from the cabin heater being used.

No, it's not passive. The power draw on app preheat is 2X the draw of just the cabin heater at full power. Also there's no way the battery pack is anywhere near that inefficient (any inefficiency results in heating).

 

[Doug_G]

Thanks, that seems to confirm my observations for the last couple of days.

I also noticed the other day, after having parked for a full day (8hours) inside a heated garage at 12C (54F), that regen was still limited to roughly 30kw. I guess one really needs 20C (68F) and above to get immediately full regen?

My best estimate - you get full regen when the pack is at or above approximately 7C (45F). (Definitely < 10 and > 5).

 

[N..8]

No, it's not passive. The power draw on app preheat is 2X the draw of just the cabin heater at full power. Also there's no way the battery pack is anywhere near that inefficient (any inefficiency results in heating).

Doug, Thanks....I just read your Blog, nice info. One question, you said that the battery and cabin heaters pull around 12 kW is that kWh?