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Discussion Starter · #1 ·
Anybody know if there has been mention of a heat pump for cabin HVAC? My guess is NO, my hope is YES. The biggest annoyance in an EV in my experience is heating the cabin, because in our Bolt those 9kW strip heaters can really eat into your range. So I find myself playing games with it, I'll turn it off and on, but then inevitably I start getting window fogging so it ends up up being an annoying dance.

And I live in a mild climate! I don't know why this isn't an option on most EV's. I know that it's not a complete solution - you still need heating strips for defrost, it doesn't work in very cold conditions, etc. I also know that it's probably not as much of an issue as I think, in reality it's not using that much power. But I still want the option GM!
 

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Discussion Starter · #3 ·
Yes it will have a heat pump. They are pretty common now, Tesla is using, my wife’s RAV4 has one.
Great news! Where did you hear that?

I'm wouldn't say they're common though, EV mfgs were very conscious of them from the beginning (Tesla had them early, and I have a memory even the EV1 had one). But for some reason - maybe cost - it's hit or miss. VW has been leaving them off I believe, and pretty sure the Lightning doesn't. For the Bolt they made a conscious decision, I believe due to cost, to leave it out.
 

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Discussion Starter · #6 · (Edited)
Assuming this article


Some oddities
  • It doesn’t specifically say Silverado, but all future Ultium platform autos, so presumably but not confirmed
  • This is technically a scavenging system, which basically all EV’s have. Many share it between HVAC and battery, which is a problem if you’re trying to use the AC while fast charging (not uncommon). Better systems have a separate system for HVAC, and for battery conditioning.
  • Maybe lost in translation, but the blurb says “Scavenges humidity” which is wrong. A head pump is simply a refrigeration unit which has variable control/servoing, and can run both ways. Either pulling or pushing heat. Humidity has nothing to do with it. But this doesn’t specifically say that it is an ambient HVAC heat pump - it’s simply a fancy scavenger/battery balancer, with access to the cabin HVAC.
  • Which as mentioned above may not be a good thing. If this is it - which seems probable for cost savings, then you man not get your fancy 350 kW (peak) charging if you use the AC, as then this system would not have cooling capacity, unless it happens to have separated systems (which apparently it doesn’t).
  • The Bolt uses a cooling plate, which is a great passive system for cooling the battery, transmission and motor. Watching OBD I see that it’s the motor that looks like generates the most heat (130-150F running temp). But for defog capability you probably still need a strip heater in there somewhere.
Possibly one clue is the humidity bit, perhaps what they mean by that is that this system can also provide dehumidifying/defogging capability but scavenging cabin heat, thereby avoiding the complications of a resistive heat strip. If so that’s great! However we might still be limited on cooling capability while fast charging.

The article above expands on this some more, but basically still says it’s a recovery system which as I say they all have. Still unknown if it pulls heat from ambient, if it has resistive elements, and what the capacity it relative to both HVAC and fast charging.

So I think the jury is out, but my engineering sense says this is somewhat encouraging.
 

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The jury isn’t out. I found the fastest link I could. It’s a heat pump just like every other ev now except for a couple. Why don’t you do some of your own research, expanding relentlessly with bad info from one crappy article is a complete waste of time. The heat pump in the RAV4 can heat and cool the battery while heating and cooling the cabin, including scavenging heat from the engine coolant or adding it to the coolant when needed. None of this is new or a mystery. Tesla does the same thing with their octovalve, I assume Hyundai/Kia act similarly. You have a budget ev designed by the Koreans using an existing ICE platform, the Silverado and any other dedicated EV platform will be light years past your hatchback, there is no point in comparing or expanding on your own ignorance.

here’s some more I just found, a step above a consumer electronics blog.

 

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Discussion Starter · #8 ·
The jury isn’t out. I found the fastest link I could.
Whoa, what the hell? Cool down, first of all I mis typed and and meant to say the jury isn’t out which should be clear from context. Second, I did a ton of searching and just came up with Ultium articles and picked one. When you said the GM docs I thought you meant there was something published on the Silverado specifically, but all I’m finding is Ultium. My point above is that we’re talking about different things. The question in the thread which I see I didn’t make clear enough, is about a HVAC heat pump from ambient, not a scavenging system from the internal systems, which as I said but apparently you didn’t read, is of course common.

OK? Chill out folks, we’re all cool here (bad pun)
 

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Silverado is ultium, they all share the same batteries and technology. Every heat pump system can scavenge heat from the condenser or the evaporator, that’s how they work, maybe the terminology is different I don’t know. The new tech in automotive heat pumps is scavenging heat from batteries and motors too. This is what GM wants to talk about, I think most would assume that the cabin could be heated from external air because that’s how ALL heat pumps work, on everyone’s current EVs including my wife’s.*

*except for below 14 degrees, same as all heat pumps. My wife’s uses the engine in such a scenario, I assume GM will have resistive heat, the teslas just have no heat until the motors get warm or none at all as discovered last winter by Canadian Tesla owners… sucks
 

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Direct from GM:

"Today, GM announced a feature standard in its Ultium-based EVs that captures and repurposes waste energy from the battery. Through the Ultium Platform’s energy recovery system, this waste energy can increase a vehicle’s range, reduce battery energy needed for heating, increase charging speed and even enable sportier driving. "

GM Ultium heat pump press release

The heat recovery heat pump is "standard" on Ultium-based EVs. Everything from the $30K Equinox to the Hummer EV. E From what I've seen from some of the patents, the new heat pump is ingeniously-simple...probably is less expensive both in parts and labor than the Bolt's HVAC/EV thermal management system, with just one glycol loop, one expansion tank, and fewer pumps. They replace the Bolt's three independent glycol loops and two PTC-glycol heaters (one for cabin heat, one for battery heat) with a single PTC glycol heater for the entire glycol loop.The Bolt's cabin HVAC glycol-based heating coil is replaced with a refrigerant condensing coil. Per owners' manuals, the much-larger 100 kWh Ultium-based Lyriq only requires 11.4 qt. of glycol as compared to the Bolt's 13 qts. Lyriq has two pumps. The Bolt has three. Defogging, the most inefficient winter HVAC mode for all EV, (Bolt typically uses 7 kW or more) is extremely efficient, at extremely cold temperatures typically using 3 kW or less, as it recovers all the compressor heat + cabin humidity latent heat for re-heating the dried/dehumidified defogging supply air.
 
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