Riddle me this (battery still cold after 5 hours L2 charging)

[pcons]

So one thing I'm increasingly a bit dissatisfied with is some of the cold weather quirks with the model 3 that I haven't experienced with other EVs. Most are not even worth griping about publicly, but tonight a perplexing one happened.

I basically charged for 5.5 hours at 30A/240V in the cold and after that you would figure the battery would be warm enough to have no Regen dots, but half the Regen bar was still full with dots. See attached pic.

It is cold out now, but I don't get how 5.5 hours of charging doesn't leave me with a warm battery. As you can see in the pic it's not like I charged to 100% where the charge rate tapers drastically. The car was still pulling a full 30A when I unplugged, and when I got in the car to drive away I got a reduced Regen message....so does that mean that once it's below -10c consistently there will be no way to have no Regen dots (other than driving for an hour I guess?)

Ok, rant over. Still love the car

 

[Lon12]

I wish we had a display of the battery temperature somewhere. Would really help us understand what’s going on.

 

[bijan]

I believe running climate especially while plugged in can warm the battery. I believe I got to no regen dots doing that though it wasn't as cold.

Otherwise the car isn't using power for heating it explicitly as that would slow charging and waste energy. Battery just warms up a bit as a side effect.

 

[pcons]

I believe running climate especially while plugged in can warm the battery. I believe I got to no regen dots doing that though it wasn't as cold.

Otherwise the car isn't using power for heating it explicitly as that would slow charging and waste energy. Battery just warms up a bit as a side effect.

I guess maybe they makes sense if the heating loop is tied to the battery heating loop. In the Volt they are separate loops independent of one another.

It still makes no sense why they wouldn't heat the battery while charging. I hate to keep saying it, but the Volt and Bolt don't do this also the battery heater in those cars only draws 1-2 kW, and doesn't need to run constantly.

If tesla is babying the batteries by limiting Regen, why not just warm the battery since it will always be happier warm. Also, given the huge phantom losses (again compared with the Volt and Bolt) I'm surprised it isn't heating the battery while plugged in. It should basically run like having a block heater on an ice car. 12A/120V or 6A/240V is all you need, and it doesn't need to be on all the time just until a threshold is reached. Say a 10C battery temp.

 

[pcons]

It occurred to me after writing my last post that the battery heater may have actually been working but it may just have been set to a setpoint like 10 degrees. That's the problem with not having a battery temp or at least a battery coolant temp. Maybe the level of regen dots that I saw indicates the battery is only at 10 degrees c and they're still limiting reagent at that temperature.

On the Chevy Volt forums one of the main engineers for the volt was an active member and he would answer technucal questions like this quite often, or at least provide some insight. Too bad Tesla doesn't have somebody like that on these forums. Then again this individual did it on his own, it's not like it was part of his job description. But he was a good source of information on how the volt worked under the hood.

I still think that charging for 5.5 hours should leave you with no Regen dots. Otherwise even if you have charging at work you will basically never see full Regen in the winter.

 

[bijan]

I guess maybe they makes sense if the heating loop is tied to the battery heating loop. In the Volt they are separate loops independent of one another.

It still makes no sense why they wouldn't heat the battery while charging. I hate to keep saying it, but the Volt and Bolt don't do this also the battery heater in those cars only draws 1-2 kW, and doesn't need to run constantly.

If tesla is babying the batteries by limiting Regen, why not just warm the battery since it will always be happier warm. Also, given the huge phantom losses (again compared with the Volt and Bolt) I'm surprised it isn't heating the battery while plugged in. It should basically run like having a block heater on an ice car. 12A/120V or 6A/240V is all you need, and it doesn't need to be on all the time just until a threshold is reached. Say a 10C battery temp.

I think they heat the battery when snowflake icon is there, which is what I'm seeing at work. Charging rate is below the normal but amps and voltage are normal. But I think once that is over they don't heat it any more. Again I think it is so that you get maximum charge per time. Like if you can charge to 90% in 8 hours, it might take longer if they had to heat the battery to the point of no regen dots (that energy is going to heating the battery and not into the cells). When you do pre-conditioning with the car plugged in they can use all the power for heating cabin plus heating battery.

I believe the model 3 has no dedicated heater battery heater but it can run power wastefully through the engines or other systems to generate heat and I don't think that is triggered fully when recharging with no snowflake icon, but is triggered when pre-conditioning especially when plugged in.

 

[bijan]

I still think that charging for 5.5 hours should leave you with no Regen dots. Otherwise even if you have charging at work you will basically never see full Regen in the winter.

Again I think if you have charging at work you can run climate while plugged in half an hour or so before you leave and you will get a warm battery.

I can test it out today

 

[puzz1ed]

Similar story here. Haven't seen no dots in a while. Perhaps it's more efficient to not fully warm the battery. After all, sub-zero temperatures probably take a lot of energy to actively counteract on a continuing basis even when driving.

 

[dusdev]

I think you may be making an assumption that the regen function is strictly related to the battery temperature. It could also be related to the temperature of the motor and the components between the motor and the power system. During charging the on-board charger to the battery will be heated. But the motor and related components are still cold soaked. I suspect it's all going to play a role in the regen-ability.

That said, this morning I warmed the car for 1 hour before departing. Car is parked in garage. I also started it charging for 10 minutes before departure. Prior charge completed 1 hour prior. There were some regen dots but nominally no regen limited message and regen was pretty strong feeling at low speeds.

 

[bijan]

Actually seems to be running the battery heating system even now that the snowflake icon is gone, but it might be because part of my battery is still marked as blue.

 

[ItsNotAboutTheMoney]

30A@240V =7.2kW
90% efficiency => 10% loss
7.2kW × 10% = 0.72kW
That's not a powerful battery heater.
As other suggest, I think that cabin heating would have directed more of the power away from charging to heating the coolant loop that helps heat the battery.

 

[bijan]

30A@240V =7.2kW
90% efficiency => 10% loss
7.2kW × 10% = 0.72kW
That's not a powerful battery heater.
As other suggest, I think that cabin heating would have directed more of the power away from charging to heating the coolant loop that helps heat the battery.

I got to work with snowflake icon and part of my battery marked blue and efficiency for the past half hour has been 50%... So I think if battery is very cold it does push more power to the battery heating loop, but if not I think you're right and it is pretty efficient.

 

[ewoodrick]

30A@240V =7.2kW
90% efficiency => 10% loss
7.2kW × 10% = 0.72kW
That's not a powerful battery heater.
As other suggest, I think that cabin heating would have directed more of the power away from charging to heating the coolant loop that helps heat the battery.

When full, the charge currents should be a lot lower, which does suggest that the power is going somewhere else. I was charging for a trip to 100% and the current was still really high, even though the car was full and the garage was about 70.
It feels that there's a bug somewhere

 

[EV Powers]

On the Chevy Volt forums one of the main engineers for the volt was an active member and he would answer technucal questions like this quite often, or at least provide some insight. Too bad Tesla doesn't have somebody like that on these forums. Then again this individual did it on his own, it's not like it was part of his job description. But he was a good source of information on how the volt worked under the hood.

Mechanics and consumers have access to full diagnostic tools to work on Volts and Bolts.

Unfortunately the same level of diagnostic tools are not available to work on Teslas.

That makes a big difference in what technical info will end up on forums, or anywhere for that matter.

 

[SSedan]

I think you may be making an assumption that the regen function is strictly related to the battery temperature. It could also be related to the temperature of the motor and the components between the motor and the power system. During charging the on-board charger to the battery will be heated. But the motor and related components are still cold soaked. I suspect it's all going to play a role in the regen-ability.

That said, this morning I warmed the car for 1 hour before departing. Car is parked in garage. I also started it charging for 10 minutes before departure. Prior charge completed 1 hour prior. There were some regen dots but nominally no regen limited message and regen was pretty strong feeling at low speeds.

With a 3 the motor is the battery heater.
Battery seems to heat enough for the set charging level.
Now I have an S but I believe the basics still apply.
Last year I had a 30amp outlet, when leaving the house it was almost always half regen or less, and cabin/battery heating could even consume a few miles plugged in.
This year I have a HCWC usually set to 60amps, this has allowed me to time charging to end just before I leave and I am seeing much less regen limiting.
I think some of it is warming enough to charge at the available amperage and some of it is warming from the current applied.
24amps from a 30amp outlet is a very low charge rate when spread across so many cells, so it doesn't need to be all that warm and the rate is so low it doesn't create much heat.
I also suspect from an efficiency standpoint when you get down to 24amps available the heater works then the charging, with more available amps charging can run at whatever rate is possible at the battery temp DURING heating which reduces heating duration and should help warming some.

For cold climates I believe in having all the car will take available. Yes I got by on a 30amp outlet last winter but it was getting by.
With a higher amperage connection I have a much easire time scheduling charging to end at the right time. Last year on a lower amperage connection I gave up and let it charge while warm from driving home, and used the app to warm it up before I got in the shower in the morning.

Yes battery heating/Regen limiting seem like a hassle when you first have to deal with it, but you will adapt and learn to love the instant heat and great traction control that are cold weather strengths of EVs.

 

[mswlogo]

As long as the system sees it can charge efficiently and promptly at the current temp (and amp limit) it won’t warm the battery further to charge at a higher speed it can’t do anyway.

Short bursts of regen are higher current than you are charging at and will still be limited. With half regen as photo shows it might not take to long for full regen. Depends on ambient temp and how spirited the drive.

I assume it was charging at ~20 mi/hr after the first hour or so. Now if it was like ~10 mi/hr after hours of charging then that’s a problem.

The system is optimizing battery longevity and your electric bill.

Now if you did want max range by getting that battery up to full regen before starting a trip, I’m not sure myself how that is supposed to be done in Tesla’s eyes. I have Seen exactly what OP has seen and I also have a 30A Circuit.

I suspect if you turn on cabin heat while plugged in. It will heat battery. Maybe.

I wonder what it would do if OP had set it to 100% charge (indicating a long trip and wanting full range). As well as amps for charging would be tapered off and could go towards heating at the end.

 

[eric1856]

My (brief) cold weather experience has been that charging, even for a long time does not heat the battery as well as running pre-heat on HI. That pre-heat seems to do the best work of getting the battery warm. I still need to do more testing though.

 

[juliusa]

I would like the battery temperature maintained for the current function. Charging at 6kW the battery temperature should be maintained for that charging rate. Why waste the energy to warm the battery more than necessary - how would the algorithm know that I will be driving after charging is complete?

When you I start driving, I would like the battery temperature maintained properly for driving.

When I plug in at night, I want the car to charge to the preset charging level - and then stop. I don't want it to then maintain battery temperature for driving - because I may not drive right afterwards. Or even at all that day.

Finally, if I have the cabin heat on then I would want the battery temperature maintained at the proper level for driving. By turning on the heat I have indicated that I am or will be occupying the car most likely because I will be driving soon. I would like the battery heated from shore power.

As best I can tell, that is how my MS works.

 

[Funkmobile]

I would like the battery temperature maintained for the current function. Charging at 6kW the battery temperature should be maintained for that charging rate. Why waste the energy to warm the battery more than necessary - how would the algorithm know that I will be driving after charging is complete?

When you I start driving, I would like the battery temperature maintained properly for driving.

When I plug in at night, I want the car to charge to the preset charging level - and then stop. I don't want it to then maintain battery temperature for driving - because I may not drive right afterwards. Or even at all that day.

Finally, if I have the cabin heat on then I would want the battery temperature maintained at the proper level for driving. By turning on the heat I have indicated that I am or will be occupying the car most likely because I will be driving soon. I would like the battery heated from shore power.

As best I can tell, that is how my MS works.

That's why I'm hoping Tesla releases some kind of user initiated battery preconditioning feature in the upcoming "winter feature update". I want the option to burn extra kWh in order to maintain a consistent driving experience.

 

[SSedan]

You will adapt to variable regen. Do you want to have it suck down a LOT of battery range to preheat to no regen when leaving places not plugged in like work?

In my model S I believe max regen is 60kwh, 24amps at 240 is about 10% of that, so the battery temp needed to charge on a 30amp outlet is much lower than needed for regen.

You want more regen when leaving the house give the car as big a circuit as it can handle.