Cold regen questions

[tom10422]

1. I set a departure time in the charging area. When I leave I get the regen may be limited error with about six dots on the regen side. It is parked in garage on the charger. Is this an issue?
2. How long does it take to get the battery to warm up for the regen? I don't have a long drive to/from work (about 25 minutes stop/go) and it really hasn't changed.

 

[SSedan]

Normal.
Fully warming the pack for zero regen which would be 50F+ would be a huge waste of energy, think about what it takes to heat that much mass.

It does warm with use but I would say don't worry about it, cold weather only gets worse from here, you will get used to the change in how the car drives.

 

[tom10422]

OK, thank you.

 

[Webeevdrivers]

Normal.
Fully warming the pack for zero regen which would be 50F+ would be a huge waste of energy, think about what it takes to heat that much mass.

It does warm with use but I would say don't worry about it, cold weather only gets worse from here, you will get used to the change in how the car drives.

Good morning Ssedan. Could you explain your 50F number a little more? Eg. At 50F can one expect regen? It’s getting colder up here and garage is hanging around 12 to 14 degrees Celsius. I’m not sure what to expect. Outside is minus 5 C

Thank you in advance.

Signed: Cold in Canada. .

 

[SSedan]

I think on my S the numbet is 52f for the pack, below that I will see regen reduction, once the pack gets down to freezing regen is gone till the pack warms.
You will get used to it quickly.

 

[Snow Drift]

1. I set a departure time in the charging area. When I leave I get the regen may be limited error with about six dots on the regen side. It is parked in garage on the charger. Is this an issue?
2. How long does it take to get the battery to warm up for the regen? I don't have a long drive to/from work (about 25 minutes stop/go) and it really hasn't changed.

1. Yes, how long before your departure does the car finish charging? Try to get it close so the battery is warm before you leave.
2. 25 min stop/go won't really do it, you may see some dots disappear. It takes a long time depending on how cold. You can drive the car hard to try and put some heat in it, OR, click a nearby supercharger and navigate to it, that will enable preconditioning which warms it.

 

[Webeevdrivers]

I think on my S the numbet is 52f for the pack, below that I will see regen reduction, once the pack gets down to freezing regen is gone till the pack warms.
You will get used to it quickly.

Thank you.

 

[Double_J]

I haven't got the dots to go away this last week in Ontario. I warm it up for about 5 or 10 minutes (not long obviously), and drive for 1.5 hrs and still don't have full regen.

 

[Snow Drift]

I haven't got the dots to go away this last week in Ontario. I warm it up for about 5 or 10 minutes (not long obviously), and drive for 1.5 hrs and still don't have full regen.

Normal driving doesn't do it. You have to basically race the car....or just set it to navigate to a Supercharger for preconditioning.

 

[hgmichna]

I believe that it is sensible not to warm up the battery fully, because it will usually get wormer while you drive. I think that Tesla intentionally warms up the battery only to a certain temperature below optimum to avoid wasting energy.

Note that with only six dots on the left side you have almost full recuperation. On a long-distance drive at normal speeds the battery will probably warm up further. If you drive slowly, like on upcountry roads, there is no urgent need for a fully warmed battery. Seems pretty clever to me, if I interpret this correctly.

 

[pt19713]

I think on my S the numbet is 52f for the pack, below that I will see regen reduction, once the pack gets down to freezing regen is gone till the pack warms.
You will get used to it quickly.

It's different on the Y, definitely not 52F. There isn't a set temp where reduced regen is removed. I've seen my battery packs at 68-74F before the regen is fully removed.

Normal driving doesn't do it. You have to basically race the car....or just set it to navigate to a Supercharger for preconditioning.

Even flooring it multiple times doesn't heat up the battery quickly, unfortunately. Originally I thought it would but according to the SMT app, three (3) 0-60 runs back to back barely made the battery packs nudge up.

I believe that it is sensible not to warm up the battery fully, because it will usually get wormer while you drive. I think that Tesla intentionally warms up the battery only to a certain temperature below optimum to avoid wasting energy.

I don't agree with this. About 12 minutes of pre-conditioning will warm the battery to the equivalent of 35 minutes of driving. This figure will vary based upon how much in-cabin is needed since this will take priority and heat up prior to the battery packs taking the heat.

Here are some numbers when I tested:
9:32 am 65.8F
9:34 am 66.2F
9:37 am 66.7F
9:42 am 69.8F
9:44 am 73.0F
9:46 am 75.2F
9:50 am 79.7F
9:51 am 80.2F
10:00 am 82.0F

Take note of the larger increase around 9:37am-9:44 am. I believe this is the point where my cabin reached the desired temp and more heat was directed to the battery packs.

I've tested without pre-conditioning and after 35 min of driving, I'm seeing a 9F increase. If you reference the numbers above, 9F takes about 12-13 minutes during the pre-conditioning process.

Also, pre-conditioning will also allow for more brake regen energy. This can be a significant increase in range. With my driving being mostly city/urban and speeds below 55 mph, my brake regen is giving me back 34% of my energy. Cut that in half with a cold battery that limits my regen, and you're reducing my effective range by essentially removing 12 kWh from my battery pack.

Other useless info. Each motor takes 3.5 kW while pre-conditioning, so 7.0 kW. The above test cost me about $0.33 ($0.095/kW). The heat on the Y pulls 300 watts, which is quite low compared to the Teslas using the heated filaments and no heat pump (2+ kW). I'll gladly spend the $0.15-$0.30 to warm up the batteries to get the most of brake regen and a happy battery.

Test notes: Ambient was 58F. I'll do more testing when temps are below 30F consistently, which may be in ~ 1-2 months.

TLDR pre-conditioning will heat up the battery packs much faster than driving the vehicle and it will help keep the range levels higher.

 

[PagodaY]

Let me see if I understand this "pre-conditioning".

I should access the car via the app and turn on the heat in the cabin, just the heat, not the defroster. Once the cabin reaches the set temp, the majority of the power is then shifted towards heating the battery pack.

Correct?

Can I set the cabin temp to "LO" so the battery starts warming as quickly as possible? Do we know what temp the "LO" setting is?

As an alternative, can I set my navigation to a close by SuperCharger. The car will then attempt to precondition the battery without heating the cabin? Is there a way to do this remotely? I can see a scenario whereby I could set the SC destination from my kitchen 15 min before I want to leave.

The reason for this, for my situation, is that I live at an elevated location and wherever I want to drive involves an immediate drive DOWN approx 900 feet. It would be great to have that regen working right away, making up for my earlier drive UP the mtn to my home. Not to mention the care and babying of a cold battery pack.

 

[Snow Drift]

Let me see if I understand this "pre-conditioning".

I should access the car via the app and turn on the heat in the cabin, just the heat, not the defroster. Once the cabin reaches the set temp, the majority of the power is then shifted towards heating the battery pack.

Correct?

Can I set the cabin temp to "LO" so the battery starts warming as quickly as possible? Do we know what temp the "LO" setting is?

As an alternative, can I set my navigation to a close by SuperCharger. The car will then attempt to precondition the battery without heating the cabin? Is there a way to do this remotely? I can see a scenario whereby I could set the SC destination from my kitchen 15 min before I want to leave.

The reason for this, for my situation, is that I live at an elevated location and wherever I want to drive involves an immediate drive DOWN approx 900 feet. It would be great to have that regen working right away, making up for my earlier drive UP the mtn to my home. Not to mention the care and babying of a cold battery pack.

1) Via the app pre-heating/cooling is for the cabin and battery. LO would put on the air conditioning.
2) The car pre-conditions for Supercharging while driving if the navigation is going to a SC and you get x distance away from it. Make sure you find the charger first (zap icon) and then click navigate, don't just set the address in the system.

MANUAL:

Warm the cabin and Battery ahead of departure for maximum range and performance. There are several ways to precondition your vehicle:

• Mobile app preconditioning: On the mobile app, navigate to Climate > Turn On and customize the temperature at which you want to heat the cabin, which also warms the Battery as needed (see Mobile App on page 155).
  
  
• Mobile app defrost: On the mobile app, navigate to Climate > Defrost to melt snow, ice, and frost on the windshields, driver and passenger windows, mirrors, and charge port. The Battery will also warm as needed.

• Note: Tesla recommends activating the climate settings at least 30-45 minutes before departure (see Climate Controls on page 127). Preconditioning times depend on outside temperature and other factors.

• Scheduled Departure: Use to preset a time at which you want your vehicle to be ready to drive (see Scheduled Charging and Scheduled Departure on page 167).

• When parked, plug in Model Y and set a time at which you want your vehicle to be ready to drive. Your vehicle determines the appropriate time to begin charging so that charging is complete and the cabin and Battery are warm by your set departure time. See Scheduled Charging and Scheduled Departure on page 167 for more information.

• Warming the Battery Before Supercharging
  • If you are using Trip Planner (see Trip Planner on page 136) and navigate to a Supercharger station, your vehicle will allocate energy to pre-heat the Battery in cold weather. This ensures you arrive at the Supercharger with an optimal Battery temperature, reducing the amount of time it takes to charge.

 

[pt19713]

Let me see if I understand this "pre-conditioning".

I should access the car via the app and turn on the heat in the cabin, just the heat, not the defroster. Once the cabin reaches the set temp, the majority of the power is then shifted towards heating the battery pack.

Correct?

Can I set the cabin temp to "LO" so the battery starts warming as quickly as possible? Do we know what temp the "LO" setting is?

As an alternative, can I set my navigation to a close by SuperCharger. The car will then attempt to precondition the battery without heating the cabin? Is there a way to do this remotely? I can see a scenario whereby I could set the SC destination from my kitchen 15 min before I want to leave.

The reason for this, for my situation, is that I live at an elevated location and wherever I want to drive involves an immediate drive DOWN approx 900 feet. It would be great to have that regen working right away, making up for my earlier drive UP the mtn to my home. Not to mention the care and babying of a cold battery pack.

It shouldn't matter if it's the defrost or normal heat. I typically just turn on the heat since my car is in my garage in the morning and defrost isn't needed. But yeah, if you have a fairly low cabin temp, the heat in the refrigerant will help the batteries sooner.

Yes, supercharger nav trick does the same thing. I haven't tested it to see if it works while parked and from the app. I'll add that to my list of things to do.

My commute is similar to yours, just not as extreme. I have to drive up a steep hill to get out of my neighborhood, then down a steep hill to hit a main road. I'm driving up around 150' elevation change, then 350' drop in elevation down the hill.

 

[caffeinated]

@PagodaY- Are you finding that you have to use the brakes when you go down that 900 ft of elevation? I would argue that you have enough regeneration available to you if you don't need to use the brakes much. I have a somewhat similar situation, and the warnings of reduced regeneration bothered me until I realized that I was still using one pedal driving as I went down the steep hill from our neighborhood. I'm starting from temperatures in the upper 40's and I'm pre-warming the cabin for 5-10 minutes for comfort. It seems to be enough although I certainly get the warnings and see the dots on my display. I think the message is very conservative, probably for liability reasons. I'd be aware that starting cold may give you reduced regen, but if you aren't using your brakes much there is no reason to waste time and energy on strategies to warm your battery more.

 

[pt19713]

Most people are still getting over 50% of the brake regen, if not 80-90%. For most driving conditions, brake regen will be around 25-35% and on occasion 50-60%. The rare times I hit 90-100% brake regen is if I'm accelerating and letting off the throttle completely. Even going down a steep hill, if I'm working the throttle/pedal, regen is only 25-35%. Limited brake regen, for most, isn't a big deal. It's just getting a lot of attention due to the temps dropping and people having no clue what's going on.

 

[PagodaY]

Thanks for the clarification(s). I'll do the cabin pre-heat and see if that improves the battery temp at departure. And I'll try to find a way to activate the navigation while parked. The SC is about 7 miles away, so that should trigger the car to pre-condition the battery.

As far as the brakes go, yes, I do use the brakes going downhill at this point in the year. Didn't have to in early Oct, so I've definitely seen a difference based on the outside temp. Hence my search for a solution.

 

[SSedan]

I should say I don't have a scan tool to track pack temp. 52f was something I saw posted here and tracks well with what I see.
Battery size would play into how much regen can be absorbed and my 2014 P85 has a bigger pack than a y or 3, as well as different cells.

I used to worry about a bunch of preheating and scheduled charging to get back as much regen as possible. Going into my 4th winter, haven't worried about it. Not even plugging it in most nights down to high 20s. I will as it gets actually cold because acceleration is eventually limited as well.

You can waste a lot of electricity warming the pack for regen.

 

[pt19713]

You can waste a lot of electricity warming the pack for regen.

I posted the math above. My electric rates are fairly low at 0.095/kW, so pre-conditioning costs $0.15 currently and as the temps drop further, $0.30. I'm not worried about 30 cents.

 

[SSedan]

The Y heat pump certainly helps but another factor is weather, I am near Green Bay......
My definition of cold is different than much of the rest of the country. In January we usually get some teens below and I have seen -25f a few times. Once it is in the teens the pack cools pretty fast and warming it up is an exercise in futility.