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While the technology may be advantageous, it seems weird to write a whole article about it without mentioning the obvious solution: Just Heat The Battery. It's

by ajross 2y ago

While the technology may be advantageous, it seems weird to write a whole article about it without mentioning the obvious solution: Just Heat The Battery. It's true that many early EVs (and most non-Teslas even today) don't ship with battery thermal management. But they won't be getting new battery chemistry either. This is one of those Great New Technology items that smells like a failure simply because it's not competing with the thing the designers think it is. It's not enough for this to beat a cold battery with a performance delta ("5x", per the article) that would justify its additional cost. It has to beat a battery with a garden variety heat pump attached, which is a much (much) lower cost barrier.

givinguflac 2y ago
Heat pumps struggle to do much at the temperature range the article proposes. Edit: downvote me all you want, I was responding specifically to “It has to beat a battery with a garden variety heat pump attached” of which EV heat pumps are not garden variety heat pumps, which do struggle at those temperatures. Didn’t think I had to be so pedantic.
- Kirby64 2y ago
  Pretty sure the ones in most EVs today work fine at -10C, but they may lose some efficiency. The thing is, there's already mechanisms in some cars to generate waste heat specifically for this purpose. Tesla's already have the ability to run their motors 'inefficiently' generating waste heat, which can be pumped into the battery coolant and heat that. It's no better than electric strip heating, but it doesn't add any cost to the system. The real benefit, in my view, to being able to charge at cold temps is to improve overall efficiency. If you have to waste some amount of power to heat the battery then that is power that could have been used to charge the car instead...
  - superkuh 2y ago
    You bring up a great point. The battery spec is only given at -10C. That's a mild normal day's low temperature in winter in Minneapolis, USA. But it's often much colder than that for long periods of time. I wonder if this glassy layer they apply can handle -30C; a temp where above ground heat pumps are no better than electrical resistive heating.
- ajross 2y ago
  The 5x delta is stated to be at 14F. That absolutely is within the reasonable operating range of a Model Y heat pump, not sure what you're citing? It's true that there are very cold environments (Fairbanks winters, say) where in-car thermal management won't be sufficient to keep charging rates high. But those are the same environments where you can't even start a gasoline car without an engine block heater, and I don't see many "no cars in Alaska" arguments on the internet. Everything has limits, but I don't see this battery trickery having much of a home.
  - idiotsecant 2y ago
    You can start gasoline cars just fine down to 20 or 30 below, so long as you keep a good battery in it. Sometimes big diesel trucks use block heaters but gasoline cars don't need them.
    - lstodd 2y ago
      I can definitely say that old/USSR 2.7L gasoline engines for the military came with block heaters. But they were expected to start in -50C / -60F. Good luck getting anything out of an EV at those temperatures.
      - gambiting 2y ago
        There's plenty of Norwegians on YouTube testing EVs down to those kinds of temperatures and they work absolutely fine, with the caveat that they won't charge until the battery warms up. Discharging Lithium batteries at really low temperatures isn't an issue, charging them is(because it actively damages them) - but even then the threshold is -32C or around that, easily overcome even with a simple resistive heater.
        lstodd 2y ago
        Norway is not "those kind of temperatures". They get a lot of snow, and maybe -5C and that is all because Gulfstream (the reason Murmansk does not freeze, and it's much farther into Arctic). Otherwise they get it easy. Now when you move just a bit off the sea, the continental climate kicks in, and you have weeks of -15 -- -20C. On discharging lithium chemistries at those temperatures or "easily overcame with resistive" let me say that: you just don't know what you are talking about.
- Rygian 2y ago
  https://ashp.neep.org/ https://ashp.neep.org/ for a list of heat pumps that perform well in cold weather.
- deleted 2y ago
  [deleted]
cyberax 2y ago
You don't even need a heat pump. You can just slightly overvolt the charger, so that some electrical energy is lost as heat rather get than transformed into chemical bonds. > This is one of those Great New Technology items that smells like a failure simply because it's not competing with the thing the designers think it is. This technology makes no sense for fast DC charging because there's enough waste heat to keep up the battery temperature, and you can just use some of the power to heat up the battery. But it can help for slow overnight charging. Keeping battery heated all night is wasteful, but you still want to be able to charge.
- magicalhippo 2y ago
  > You don't even need a heat pump. You can just slightly overvolt the charger The BMW i3 had inductive heating strips underneath the coolant channels in the battery pack[1]. I know our i3 had a heat pump, I presume both were in play. We used our i3 down to -25C (-13F) many times, didn't have any issues. [1]: https://youtu.be/JjPIuLz5VFI?t=1124 https://youtu.be/JjPIuLz5VFI?t=1124
- OptionOfT 2y ago
  Heat pumps also serve for more efficient heating when you're driving. Just like at home where a heat pump is more efficient than a resistant heater.
- lazide 2y ago
  That doesn’t work when the problem is the battery is already sub-zero - lithium plating occurs when trying to charge in those conditions, destroying the battery. You can’t just overvolt out of that - you need an external source of heat until you’re out of the dangerous thermal area.
  - formerly_proven 2y ago
    I'm not sure if that affects all chemistries and compositions. If you look at the spec-sheet for e.g. the LG E63 cells used in some older EVs (notably without TMS), those specify charging down to -20 °C - and the owner's manuals certainly have no warnings in them that the car will implode if you charge in the winter.
jjtheblunt 2y ago
> It's true that many early EVs (and most non-Teslas even today) don't ship with battery thermal management. That’s false since at latest 2013 in the US. The past 12 years of BMW as a counterexample all have thermal management. Tesla too. You may be remembering the original Nissan Leaf?
- ajross 2y ago
  Almost all non-Tesla EVs offer a heat pump option. Most non-Tesla EVs sold do not have one. Just go to your local VW dealer or whatever and see what the specs are on the ID.4's on the lot is.
  - jjtheblunt 2y ago
    You can easily read about your example VW MEB platform battery configurations, including built in thermal management system, online at the Munro teardown, for example. Perhaps you are changing the topic from your original thermal management to heat pump systems specifically?
  - recursive 2y ago
    Those are different goal posts. There are other ways of heating a battery.
- gambiting 2y ago
  My 2022 Volkswagen e-Up has zero thermal management of the battery, it's completely passively cooled with no heating. Not that it really matters, people have tested it and charging speed only starts to degrade after 3-4 rapid charges in one day, with "rapid" in quotes(in tops out at 40kW). I believe the eGolf which was sold in the US shares the same drivetrain and battery.
  - formerly_proven 2y ago
    Different drivetrain and battery for the eGolf, but both of these are effectively 2013 EVs.
linsomniac 2y ago
Heating, in its various forms, has one big drawback that having a battery that can charge faster in low temps would be really nice in: Starting the day needing to charge. Ideally, you don't do that, but when traveling sometimes you have to stay at a place that doesn't have a charger, and it's really cold, and now rather than a 30 minute charge it's more like 90 minutes.
jbm 2y ago
In winter, I lose 5-10% of my battery a day due to heating my battery. Tesla is nice enough to hide this under "You should keep your car plugged in all the time" messages. It's really a pain, especially if you have a relatively small battery to begin with. I have a 2019 Model 3 w/ a 50 kwh battery, and use 10-20 kwh on a regular basis; 5 kwh wasted means as much as 1/3 of my energy use is effectively waste. I'd be very interested in seeing what they can provide for us. Improved battery chemistry for use in the far north is of far, far more value than yet another 5 person car for 1 person driving in San Francisco.
- ajross 2y ago
  > In winter, I lose 5-10% of my battery a day due to heating my battery. Exactly! That sounds like a drawback when you state it like that, but what it actually means is that this magic battery doodad needs to provide 90-95% of the performance of its existing, mature competitor (assuming no other drawbacks) just to be break-even in the market. You don't disrupt markets with numbers like that.
  - gopalv 2y ago
    > what it actually means is that this magic battery doodad needs to provide 90-95% of the performance of its existing, mature competitor The problem is mostly that it does the battery draw when parked. Solid electrolytes are coming some day soon, so that we can let it freeze without killing the cells. Right now, the Tesla is hard to use in a winter sport season unless where you're driving has a charger or underground parking near a plug point. I can drive up hill to a nice ski resort, spend 3+ days taking the bus with all your shoes on without touching the car. With the batteries, they'll just run down when parked, so I cannot park it for a whole week outdoors like I can do with my Subaru. And with the low battery + low temps, it will not charge back up going downhill so the expected range drops massively by the time you're downhill. Once you navigate to a charger, the car starts running the heater and driving down range further. Watching the car battery eating its own range while driving to "Donner pass road" on your way out of Tahoe or Reno feels rather appropriately horrific.
    - 2y ago
bdcravens 2y ago
> (and most non-Teslas even today) don't ship with battery thermal management Some do but don't enable it immediately, but do so with a software upgrade. (such as what happened with Kia EV6/Hyundai Ioniq 5)
jve 2y ago
I mean this is an incremental improvement that would be very welcome. Why be so negative? Look around the products that have lived through decades of incremental improvements and compare them. Like the phone in your pocket or computer you are using.

by ajross 2y ago

givinguflac 2y ago

Heat pumps struggle to do much at the temperature range the article proposes. Edit: downvote me all you want, I was responding specifically to “It has to beat a battery with a garden variety heat pump attached” of which EV heat pumps are not garden variety heat pumps, which do struggle at those temperatures. Didn’t think I had to be so pedantic.

Kirby64 2y ago
Pretty sure the ones in most EVs today work fine at -10C, but they may lose some efficiency. The thing is, there's already mechanisms in some cars to generate waste heat specifically for this purpose. Tesla's already have the ability to run their motors 'inefficiently' generating waste heat, which can be pumped into the battery coolant and heat that. It's no better than electric strip heating, but it doesn't add any cost to the system. The real benefit, in my view, to being able to charge at cold temps is to improve overall efficiency. If you have to waste some amount of power to heat the battery then that is power that could have been used to charge the car instead...
- superkuh 2y ago
  You bring up a great point. The battery spec is only given at -10C. That's a mild normal day's low temperature in winter in Minneapolis, USA. But it's often much colder than that for long periods of time. I wonder if this glassy layer they apply can handle -30C; a temp where above ground heat pumps are no better than electrical resistive heating.
ajross 2y ago
The 5x delta is stated to be at 14F. That absolutely is within the reasonable operating range of a Model Y heat pump, not sure what you're citing? It's true that there are very cold environments (Fairbanks winters, say) where in-car thermal management won't be sufficient to keep charging rates high. But those are the same environments where you can't even start a gasoline car without an engine block heater, and I don't see many "no cars in Alaska" arguments on the internet. Everything has limits, but I don't see this battery trickery having much of a home.
- idiotsecant 2y ago
  You can start gasoline cars just fine down to 20 or 30 below, so long as you keep a good battery in it. Sometimes big diesel trucks use block heaters but gasoline cars don't need them.
  - lstodd 2y ago
    I can definitely say that old/USSR 2.7L gasoline engines for the military came with block heaters. But they were expected to start in -50C / -60F. Good luck getting anything out of an EV at those temperatures.
    - gambiting 2y ago
      There's plenty of Norwegians on YouTube testing EVs down to those kinds of temperatures and they work absolutely fine, with the caveat that they won't charge until the battery warms up. Discharging Lithium batteries at really low temperatures isn't an issue, charging them is(because it actively damages them) - but even then the threshold is -32C or around that, easily overcome even with a simple resistive heater.
      - lstodd 2y ago
        Norway is not "those kind of temperatures". They get a lot of snow, and maybe -5C and that is all because Gulfstream (the reason Murmansk does not freeze, and it's much farther into Arctic). Otherwise they get it easy. Now when you move just a bit off the sea, the continental climate kicks in, and you have weeks of -15 -- -20C. On discharging lithium chemistries at those temperatures or "easily overcame with resistive" let me say that: you just don't know what you are talking about.
Rygian 2y ago
https://ashp.neep.org/ https://ashp.neep.org/ for a list of heat pumps that perform well in cold weather.
deleted 2y ago
[deleted]

cyberax 2y ago

You don't even need a heat pump. You can just slightly overvolt the charger, so that some electrical energy is lost as heat rather get than transformed into chemical bonds. > This is one of those Great New Technology items that smells like a failure simply because it's not competing with the thing the designers think it is. This technology makes no sense for fast DC charging because there's enough waste heat to keep up the battery temperature, and you can just use some of the power to heat up the battery. But it can help for slow overnight charging. Keeping battery heated all night is wasteful, but you still want to be able to charge.

magicalhippo 2y ago
> You don't even need a heat pump. You can just slightly overvolt the charger The BMW i3 had inductive heating strips underneath the coolant channels in the battery pack[1]. I know our i3 had a heat pump, I presume both were in play. We used our i3 down to -25C (-13F) many times, didn't have any issues. [1]: https://youtu.be/JjPIuLz5VFI?t=1124 https://youtu.be/JjPIuLz5VFI?t=1124
OptionOfT 2y ago
Heat pumps also serve for more efficient heating when you're driving. Just like at home where a heat pump is more efficient than a resistant heater.
lazide 2y ago
That doesn’t work when the problem is the battery is already sub-zero - lithium plating occurs when trying to charge in those conditions, destroying the battery. You can’t just overvolt out of that - you need an external source of heat until you’re out of the dangerous thermal area.
- formerly_proven 2y ago
  I'm not sure if that affects all chemistries and compositions. If you look at the spec-sheet for e.g. the LG E63 cells used in some older EVs (notably without TMS), those specify charging down to -20 °C - and the owner's manuals certainly have no warnings in them that the car will implode if you charge in the winter.

jjtheblunt 2y ago

> It's true that many early EVs (and most non-Teslas even today) don't ship with battery thermal management. That’s false since at latest 2013 in the US. The past 12 years of BMW as a counterexample all have thermal management. Tesla too. You may be remembering the original Nissan Leaf?

ajross 2y ago
Almost all non-Tesla EVs offer a heat pump option. Most non-Tesla EVs sold do not have one. Just go to your local VW dealer or whatever and see what the specs are on the ID.4's on the lot is.
- jjtheblunt 2y ago
  You can easily read about your example VW MEB platform battery configurations, including built in thermal management system, online at the Munro teardown, for example. Perhaps you are changing the topic from your original thermal management to heat pump systems specifically?
- recursive 2y ago
  Those are different goal posts. There are other ways of heating a battery.
gambiting 2y ago
My 2022 Volkswagen e-Up has zero thermal management of the battery, it's completely passively cooled with no heating. Not that it really matters, people have tested it and charging speed only starts to degrade after 3-4 rapid charges in one day, with "rapid" in quotes(in tops out at 40kW). I believe the eGolf which was sold in the US shares the same drivetrain and battery.
- formerly_proven 2y ago
  Different drivetrain and battery for the eGolf, but both of these are effectively 2013 EVs.

linsomniac 2y ago

Heating, in its various forms, has one big drawback that having a battery that can charge faster in low temps would be really nice in: Starting the day needing to charge. Ideally, you don't do that, but when traveling sometimes you have to stay at a place that doesn't have a charger, and it's really cold, and now rather than a 30 minute charge it's more like 90 minutes.

jbm 2y ago

In winter, I lose 5-10% of my battery a day due to heating my battery. Tesla is nice enough to hide this under "You should keep your car plugged in all the time" messages. It's really a pain, especially if you have a relatively small battery to begin with. I have a 2019 Model 3 w/ a 50 kwh battery, and use 10-20 kwh on a regular basis; 5 kwh wasted means as much as 1/3 of my energy use is effectively waste. I'd be very interested in seeing what they can provide for us. Improved battery chemistry for use in the far north is of far, far more value than yet another 5 person car for 1 person driving in San Francisco.

ajross 2y ago
> In winter, I lose 5-10% of my battery a day due to heating my battery. Exactly! That sounds like a drawback when you state it like that, but what it actually means is that this magic battery doodad needs to provide 90-95% of the performance of its existing, mature competitor (assuming no other drawbacks) just to be break-even in the market. You don't disrupt markets with numbers like that.
- gopalv 2y ago
  > what it actually means is that this magic battery doodad needs to provide 90-95% of the performance of its existing, mature competitor The problem is mostly that it does the battery draw when parked. Solid electrolytes are coming some day soon, so that we can let it freeze without killing the cells. Right now, the Tesla is hard to use in a winter sport season unless where you're driving has a charger or underground parking near a plug point. I can drive up hill to a nice ski resort, spend 3+ days taking the bus with all your shoes on without touching the car. With the batteries, they'll just run down when parked, so I cannot park it for a whole week outdoors like I can do with my Subaru. And with the low battery + low temps, it will not charge back up going downhill so the expected range drops massively by the time you're downhill. Once you navigate to a charger, the car starts running the heater and driving down range further. Watching the car battery eating its own range while driving to "Donner pass road" on your way out of Tahoe or Reno feels rather appropriately horrific.
  - 2y ago

bdcravens 2y ago

> (and most non-Teslas even today) don't ship with battery thermal management Some do but don't enable it immediately, but do so with a software upgrade. (such as what happened with Kia EV6/Hyundai Ioniq 5)

jve 2y ago

I mean this is an incremental improvement that would be very welcome. Why be so negative? Look around the products that have lived through decades of incremental improvements and compare them. Like the phone in your pocket or computer you are using.