Battery Thermal Management

The manual recommends plugging in below 32F and over 32C when it's parked, to keep the battery conditioned and promote longevity. Plugging in allows the TMS to run without reducing range. But what if plugging in isn't possible?

Will the TMS operate, unplugged, in extreme temperatures?

If so, how much power consumption can we expect, on average?

If it doesn't operate unplugged, what is the recommended time limit it can be out in extremely hot or cold weather before it must be plugged in or moved into climate controlled parking?

Thanks

They don't want to deal with this one either? That could be a problem Amber. The Bolt has thermal management but gives no indication of battery temperature. How will we know if the system is functioning properly? A temperature gauge should be standard on any EV. But again, someone will figure out how to get that data from the can bus and give it to us in a spy app.

DNAinaGoodWay said:

The manual recommends plugging in below 32F and over 32C when it's parked, to keep the battery conditioned and promote longevity. Plugging in allows the TMS to run without reducing range. But what if plugging in isn't possible?

Will the TMS operate, unplugged, in extreme temperatures?

If so, how much power consumption can we expect, on average?

If it doesn't operate unplugged, what is the recommended time limit it can be out in extremely hot or cold weather before it must be plugged in or moved into climate controlled parking?

Thanks

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Good morning DNAinaGoodWay!

I am truly sorry for the delay in follow up, but I wanted to be sure I was getting you the most detailed and accurate information possible.

It is recommended that the vehicle be plugged in when temperatures are below 0 °C (32 °F) and above 32 °C (90 °F) to maximize high voltage battery life. The Bolt EV’s proprietary thermal management system has been designed and tuned to provide optimal battery temperature under all operating conditions.

To prevent vehicle immobilization in cold temperatures, we recommend enabling Climate Notifications in the myChevrolet app. When enabled, you will received an alert if extremely cold temperatures are forecasted in your area within 36 hours of the time you select in the app. The Bolt EV thermal management system employs a comprehensive set of diagnostic tests to ensure all sensors and actuators are functioning as desired. A "Service Vehicle Soon" light will illuminate if a problem has been detected. To monitor thermal management activity, use the Energy Details screen to see what percentage of your recent energy has been allocated to battery conditioning.

If you have any additional questions or concerns about this, please feel free to follow up with me via private message.

Best,

Amber G.
Chevrolet Customer Care

DNAinaGoodWay said:

Will the TMS operate, unplugged, in extreme temperatures?

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This is the pertinent question for me also. During the winter months, it is below freezing almost every night (excepting only the rare warm spell). Do I really need to plug in every single night? This is a change in behavior from my Leaf, and will require juggling cars in the driveway. Normally I only charge during the day and leave it unplugged at night.

ChevyCustomerCare said:

It is recommended that the vehicle be plugged in when temperatures are below 0 °C (32 °F) and above 32 °C (90 °F) to maximize high voltage battery life. The Bolt EV’s proprietary thermal management system has been designed and tuned to provide optimal battery temperature under all operating conditions.

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This isn't always possible, such as at work, school or such. Is there some way to determine the temperature of the battery?

I think what she's saying is the TMS will operate unplugged and you can track its power usage on the energy screen. But they're not giving us any estimate of how much it might draw, so we'll have to figure that out ourselves.

There may be a way to monitor pack temperature with the Chevy app, others have suggested that in other threads, but I haven't seen anything definitive yet.
Hopefully GM will take our suggestions and add a gauge on the next version.

The SVS light is wholly inadequate. A gauge would give a driver earlier warning of a problem and maybe avoid damage.

Likewise having the app warn me about cold weather coming, I already track the weather. What I need to know is how long can the pack endure it unplugged. Given it's thermal mass and likely insulation I'm guessing it could go at least a day unplugged even if the TMS failed.

DNAinaGoodWay said:

I think what she's saying is the TMS will operate unplugged

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I would hope this is the case, but can anyone confirm it for certain? Either a Chevy Rep, or somewhere in the manual?

I don't see it in the manual, but I think this statement covers it:

The Bolt EV’s proprietary thermal management system has been designed and tuned to provide Optimal battery temperature under all operating conditions.

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I assume any statement she makes here has been parsed by engineering, management, and legal since it would likely be admissible as evidence if it came to that.

Recall all of the early battery degradation and early failures with original Leaf batteries. Nissan had to change chemistries to combat this.. Nevertheless, with the passive cooling system, if seems they still degrade at a higher rate. They heat up while driving and sitting outside in hot weather, and chill below acceptable Li temperatures in winter, with no way to correct either without parking in a climate controlled area, or driving the vehicle.

The active TMS in the Bolt is one of the selling points to me, and perhaps other data geeks out there. Trying to actively shave the peaks and valleys of the battery temperature seems that is will add a great deal to the life o the battery.

I suspect TMS works without being plugged in. Unlike in the Volt, the Bolt has a "battery conditioning" segment on the pie chart. It wouldn't be there if it only thermo-managed when plugged in, no? I don't know of any electric vehicle with a TMS that requires the car to be plugged in.

They heat up while driving and sitting outside in hot weather, and chill below acceptable Li temperatures in winter, with no way to correct either without parking in a climate controlled area, or driving the vehicle.

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You're half right. Since 2012 or 2013 Leafs have come with a battery warmer that uses only 300 watts and comes on automatically if the pack temp (not the air temp) falls below about 6F. Mine runs once or twice in a typical Winter in Upstate NY. It's heat that Leaf drivers have to worry about regarding the pack, not cold.

LeftieBiker said:

They heat up while driving and sitting outside in hot weather, and chill below acceptable Li temperatures in winter, with no way to correct either without parking in a climate controlled area, or driving the vehicle.

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You're half right. Since 2012 or 2013 Leafs have come with a battery warmer that uses only 300 watts and comes on automatically if the pack temp (not the air temp) falls below about 6F. Mine runs once or twice in a typical Winter in Upstate NY. It's heat that Leaf drivers have to worry about regarding the pack, not cold.

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Nissan added the battery heater to late 2011 models, with the Cold Weather package. It has been standard on every Leaf model years 2012+. The intent of the heater is to prevent the electrolyte from freezing. If it did, the pack would be completely useless. Bricked.

The trouble is, lithium batteries temporarily lose capacity when cold. They simply cannot hold as much energy at 30F as they can at 70F. In fact, Tony Williams reports that the Leaf's battery is ideal around 70F, and loses about 1% for each 4F below that. So at 30F, the battery only holds about 90% of nominal.

What Nissan did not do (and I wish they had) is use the heater to keep the battery a little warmer in the winter. Run it while the car is plugged in, so that the battery can hold just a little more juice. This is what I suspect the Bolt's TMS is doing.

GetOffYourGas said:

DNAinaGoodWay said:

Will the TMS operate, unplugged, in extreme temperatures?

Click to expand...

This is the pertinent question for me also. During the winter months, it is below freezing almost every night (excepting only the rare warm spell). Do I really need to plug in every single night? This is a change in behavior from my Leaf, and will require juggling cars in the driveway. Normally I only charge during the day and leave it unplugged at night.

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Good morning, GetOffYourGas!

We've conditioned the battery for optimal battery life and performance when plugged in. For extremely low temperature concerns, leaving the car unplugged with OnStar Climate Notifications enabled should prevent vehicle immobilization.

While driving, the Battery Management System will protect the battery even at low temperatures. As stated on page 258 of your owner's manual, if temperatures get extremely cold or hot, you may see “Propulsion Power Reduced” or “BATTERY TOO COLD, PLUG IN TO WARM."

Let me know if you have additional questions.

Warm Wishes,

Amber G.
Chevrolet Customer Care

Thanks for the reply Amber.

My specific question is this - if the car is off / unplugged, will the TMS use battery power to keep the battery warm during a cold night? Or will OnStar simply alert you when it is getting too cold?

A little more background, if it helps - currently my BEV sits in the driveway, unplugged overnight while my wife's PHEV sits charging in the garage. I charge the BEV exclusively at work during the week. If the Bolt requires being plugged in, it will require a little extra juggling of cars on my part. By no means a deal killer, but I would like to know how to best care for my cars.

Thanks!

new to the board... is there a definite answer to question - does the TMS work on the Bolt if it is unplugged and sitting in a parking lot at 10 degrees F ? If the car can't go for 8 hours at 10 degrees without the battery dying it seems useless here in upstate NY.

So I really need an answer from Chevy to this question: If the Bolt is parked UNPLUGGED in very cold conditions, will the battery thermal protection work, and how much battery capacity will the thermal protection use?

I live in a climate where it is below freezing for about 4 months per year, and often gets into the -10F to -20F range for brief periods. I'm happy to use some battery capacity to protect the battery. But my car is unplugged and outside during the work day or when I'm skiing. I need to know the battery isn't going to get bricked during the first cold snap.

My Volt has been fine in these cold conditions the last 3 winters, so I would assume the Bolt will be as good or better. My Volt gets about a 30-40% drop in battery range in winter compared to summer. I'm fine trading range for battery protection with a Bolt. My Bolt will be plugged in in a heated garage at night so I will start each day with a full charge, a warm battery and plenty of excess capacity.

GetOffYourGas said:

Thanks for the reply Amber.

My specific question is this - if the car is off / unplugged, will the TMS use battery power to keep the battery warm during a cold night? Or will OnStar simply alert you when it is getting too cold?

A little more background, if it helps - currently my BEV sits in the driveway, unplugged overnight while my wife's PHEV sits charging in the garage. I charge the BEV exclusively at work during the week. If the Bolt requires being plugged in, it will require a little extra juggling of cars on my part. By no means a deal killer, but I would like to know how to best care for my cars.

Thanks!

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Hey Brian,

Thanks for your patience on this one! We’ve been working with our internal resources to gather additional insight for you. They've stated that you should not have any concerns when leaving your vehicle untethered overnight (unless temperatures are continuously below -40 degrees Fahrenheit). This has been tested and validated by our internal team. Additionally, any energy used for battery conditioning will be displayed on the “Energy Details Screen,” so you’ll be able to view that whenever you like.

If you have additional questions, we’re more than happy to help! We can be reached by private message or by email at [email protected].

Kindly,
Lauren E.
Chevrolet Customer Care

The question was : If the Bolt is parked UNPLUGGED in very cold conditions, will the battery thermal protection work, and how much battery capacity will the thermal protection use?

It sounds as if you are saying that YES, if parked unplugged in very cold conditions, the battery thermal protection will activate. Am I correct in my assumption?

But, you haven't stated how much battery capacity will thermal protection use. You have stated that it is possible to see how much has been used after the fact, but that is too late to avoid damage if there isn't enough energy in the battery to start with. Can you answer this question?

Thank you.

It's likely that GM borrowed from Nissan here, and programmed the battery heating to come on only at very low temps (pack temp below 10F) and then shut off before the pack gets critically low. The Leaf heater shuts off when charge drops to 30%. It would indeed be nice, though, to know for a fact what the Bolt will do.

The only time this is likely to be an issue is when then a Bolt gets left unused, in frigid temps, for several days or more. The packs have a lot of thermal mass.

All I can tell you is this:
I bought my car in CA. Shipped to Ne. Took 4 days. Salesperson charged the car to full before it was shipped. Went through Colorado and Wyoming in 1st week of January. It was cold. When I received the car when looking at the energy screen it had used "battery condition" for a certain percentage. So to me it must use the "battery conditioning" while unplugged if cold enough.