Rumors abound that Tesla will start using a heat pump on the model 3 like they do on the Y. Of course this will reduce the range hit during the winter, but what about summer? Will the added weight reduce summer range?
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Will the extra weight of a heat pump reduce summer range?
- Thread starter theothertom
- Start date
How much extra weight do you think it would add, even supposing it will be fitted?
Let us pretend it will be 10 extra pounds, doubt it would be that much.
Are you so cripplingly academic or incapable of rational thought that you actually believe that makes a calculable difference in a 4000lbs. car?
When talking "range" let us pretend long distance highway is the concern, weight is of little consequence in highway driving because acceleration is where weight hurts most and you aren't accelerating much. Yeah you could make an argument about rolling resistance but 10lbs isn't going to matter.
Now for "efficiency" or overall day to day energy use weight will usually play a bigger roll as acceleration is a bigger portion of total energy use, but again 10lbs on a 4000lbs car is .0025% weight gain. If we pretend .0025 weight gain will reduce range .0025% that would work out to less than a mile reduction in range.........
.....
If your worried about that you should probably make sure there is only ever two squirts of washer fluid in the reservoir so you aren't wasting all that energy carrying around an extra gallon of washer fluid.
Maybe consider going commando so you aren't driving around with all that extra underwear weight.
Edit, I rushed the math and didn't put the decimal in the right place above. The point stands 10lbs is peanuts in a 4000lbs car.
Are you so cripplingly academic or incapable of rational thought that you actually believe that makes a calculable difference in a 4000lbs. car?
When talking "range" let us pretend long distance highway is the concern, weight is of little consequence in highway driving because acceleration is where weight hurts most and you aren't accelerating much. Yeah you could make an argument about rolling resistance but 10lbs isn't going to matter.
Now for "efficiency" or overall day to day energy use weight will usually play a bigger roll as acceleration is a bigger portion of total energy use, but again 10lbs on a 4000lbs car is .0025% weight gain. If we pretend .0025 weight gain will reduce range .0025% that would work out to less than a mile reduction in range.........
.....
If your worried about that you should probably make sure there is only ever two squirts of washer fluid in the reservoir so you aren't wasting all that energy carrying around an extra gallon of washer fluid.
Maybe consider going commando so you aren't driving around with all that extra underwear weight.
Edit, I rushed the math and didn't put the decimal in the right place above. The point stands 10lbs is peanuts in a 4000lbs car.
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Given the context of this forum, this isn't a super ridiculous question really.
- Plenty of people here swear that lightweight Ohmmu 12V battery extends range due to the reduced weight.
- I'd be surprised if most people here know what additional parts are necessary for the heat pump conversion, or what weight is saved by removing the PTC heater. Thus the weight difference is a bit unknown. Surely with words thrown around like "OCTOVALVE" it sounds like a lot more is going on, right?
- The difference between the LR RWD and SR+ is about 500lbs, yet the SR+ has noticeably better Wh/mi rating.
- Hills are an example of where weight matters (more energy required going up, only a fraction of which can be recovered by regen going down)
- We're all bad at math here (10lb/4000lb is 0.25%, not 0.0025%
)
Given the context of this forum, this isn't a super ridiculous question really.
But ultimately I agree. This is probably going to be plus or minus a few tens of pounds at most, and comes with other changes as well.
- Plenty of people here swear that lightweight Ohmmu 12V battery extends range due to the reduced weight.
- I'd be surprised if most people here know what additional parts are necessary for the heat pump conversion, or what weight is saved by removing the PTC heater. Thus the weight difference is a bit unknown. Surely with words thrown around like "OCTOVALVE" it sounds like a lot more is going on, right?
- The difference between the LR RWD and SR+ is about 500lbs, yet the SR+ has noticeably better Wh/mi rating.
- Hills are an example of where weight matters (more energy required going up, only a fraction of which can be recovered by regen going down)
- We're all bad at math here (10lb/4000lb is 0.25%, not 0.0025%
I think #2 is the key point. I suspect most people don't know that an air conditioner and a heat pump are basically the same thing. There are many things I don't know that could result in me asking what seems like to naive question so I try to be empathetic to the questioner.
The Tesla situation is a bit more complicated because of the innovation done around the the system they built. It is possible that some weight would be lost instead of gained.
Agreed (though I admit the "try to be empathetic" is character development in my case, not something I started with
).Something your post made me realize (somehow) is that some folks do have a reference for what a heat pump is. They're huge things used for HVAC in buildings and/or homes. They're not light, and they're not small, but they are known as "heat pumps".
At that point you can also point out a home air conditioner is huge compared to a car's (unless comparing to a window unit or something). I think that comparison is only obvious in hindsight, or if you know to equate an air conditioning system to a heat pump already.
On the point of innovation, I think the only weird thing they're doing is using the compressor in a waste heat mode when added heat is required (instead of some dedicated resistive thing). Kind of like how they use the drive motors in waste modes to heat the battery. And indeed, this does result in saved weight!
ucmndd
Well-Known Member
A response that's not only correct, but efficient!
@camalaio thank you for the math correction. I rushed the math because i found the question irritatingly stupid.
On the lithium 12volt range claims yeah and someone posted a video about the wonders of skinny tires on a 3 and drastic range increase, trouble is he claimed normal at 80mph was 360wh/m and the skinny tires was 260wh/m. 360 was a bull turds number my P85 is around that or better if there is enough traffic. Another guy claimed ceramic wheel were good for a 17% increase in range.
To those who really have no idea what a heat pump is, think of it like running air conditioning backwards. Yeah that might be a gross oversimplification but it works. The major parts are there, the compressor, fans, heat exchangers, not to say it is simple as some valving to run stuff backwards, but exchanging parts really isn't adding some huge new system.
On the lithium 12volt range claims
yeah and someone posted a video about the wonders of skinny tires on a 3 and drastic range increase, trouble is he claimed normal at 80mph was 360wh/m and the skinny tires was 260wh/m. 360 was a bull turds number my P85 is around that or better if there is enough traffic. Another guy claimed ceramic wheel were good for a 17% increase in range.To those who really have no idea what a heat pump is, think of it like running air conditioning backwards. Yeah that might be a gross oversimplification but it works. The major parts are there, the compressor, fans, heat exchangers, not to say it is simple as some valving to run stuff backwards, but exchanging parts really isn't adding some huge new system.
smatthew
Active Member
The heat pump may even increase summer range. Some people have reported that the Model 3 uses the heater along with the air conditioning. Sometimes as much as 2kW of heat. The Model Y can use the heat pump to both heat and cool the air at the same time, so efficiency will definitely go up by a tiny bit in the summer.
While it is true cars will run heating and cooling at the same time to dehumidify air without over chilling.
I am curious how you think they will manage that with a heat pump?
smatthew
Active Member
I believe the Y has an evaporator AND a condenser in the air system. So it can indeed heat and cool at the same time to dehumidify.
edit: Here's the patent: US20190070924A1 - Optimal source electric vehicle heat pump with extreme temperature heating capability and efficient thermal preconditioning - Google Patents
"
According to a fifth aspect of the first embodiment, the vehicle heat pump system further includes a cabin HVAC case that contains the cabin evaporator and the cabin condenser. The cabin HVAC case may be configured to operate in an air recirculation mode to recirculate air within the cabin or a fresh air mode that communicates air between the cabin and the ambient or a combination of these modes. The particular operation may be selected based upon ambient temperature, cabin temperature, and/or cabin humidity levels.
According to a sixth aspect of the first embodiment, the cabin evaporator and the cabin condenser may be configured in at least one heating mode to operate concurrently. By operating in this heating mode, the vehicle heat pump system is in a positive feedback operation to accelerate cabin heating."
In the image below, #306 is the HVAC case inside the car. Notice that it has both an evaporator and a condenser.
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gavine
Petrol Head turned EV Enthusiast
We're all bad at math here (10lb/4000lb is 0.25%, not 0.0025%
Remove the % sign and 0.0025 is correct.....0.25% = 0.0025 (I think
)
PalmBeachPaul
Member
Just to add a bit of levity. In college I had friends who would brag that their bicycle was made of x material and weighed 5 lbs less than mine. I looked at them and told them they were 20 lbs overweight and beat them in every race. Today I’m sure I’m at least 1 heat pump overweight. I’m not worried about it.
We should really press Tesla for range charts with numbers of passengers.
If a few pounds for a heat pump upgrade is going to be hard on range, imagine bringing family with?
Maybe that should be the range mod, get rid of all your family and friends to save weight.
All the time we see posts about how if you bring your whole family range is cut dramatically due to the weight...................
If a few pounds for a heat pump upgrade is going to be hard on range, imagine bringing family with?
Maybe that should be the range mod, get rid of all your family and friends to save weight.
All the time we see posts about how if you bring your whole family range is cut dramatically due to the weight...................
smatthew
Active Member
You know, you could remove the passenger seat. And the rear seat bottom just clicks out! Might even be able to remove the rear seat backs. Think of all the weight you could be saving!
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