dhanson865
Well-Known Member
Lets try this again:
my apologies to those on mobile devices, the part you need to look at is the inset at the bottom right and the bigger a screen you have the better of a chance you'll be able to read it.
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Lets try this again:
my apologies to those on mobile devices, the part you need to look at is the inset at the bottom right and the bigger a screen you have the better of a chance you'll be able to read it.
GlmnAlyAirCar
Active Member
And how do you know this? The patent application give me some reason to believe they implemented something similar. Your unsubstantiated claims are of no merit.
The diagnostic screen only shows the chilled refrigerant (black lines) coupled in to the cabin HVAC for evaporative (defrost) purposes:
Waste heat from drive unit (moter + inverter) can be coupled in to battery (the "parallel" block valving changes to make the battery loop inline/serial) , but no such method of dumping heat in to the cabin. The "Air PTC" is the only heat source for cabin.
GlmnAlyAirCar
Active Member
That's not how I am reading the diagram. Looking at the top, we have the waste heat loop being cooled by ambient (or fan-driven) air. It also shows the AC loop being cooled the same way. This is open to interpretation, but this diagram implies that waste heat can be transferred to the AC loop, allowing it to be used as heat for the cabin. Admittedly I am making some assumptions but it is one possible way to read what's going on here. It's also consistent with the patent application. Yes, I would expect to see another "parallel" block at the top, so I am not completely convinced. But you also have to remember that much detail tends to be left out of these diagnostic synoptic pages.The diagnostic screen only shows the chilled refrigerant (black lines) coupled in to the cabin HVAC for evaporative (defrost) purposes:
Waste heat from drive unit (moter + inverter) can be coupled in to battery (the "parallel" block valving changes to make the battery loop inline/serial) , but no such method of dumping heat in to the cabin. The "Air PTC" is the only heat source for cabin.
Pull apart your car. Let us know when you find the truth.
The Mitsubishi defrost is due to poor implementation. It doesn't do condition based defrost (i.e. there is actual frost). If it's been off for a while, it starts up with a defrost cycle.You can watch it in actual operation, it will often initiate defrost without needing it, and sometimes no defrost when it needs to. Also, it has defrost cycles because it uses reverse cycle to melt the frost, it would never need to cycle with coil heaters. I believe efficiency should also go up if you stop reversing the cycle, but again at a larger initial cost.
Umm, no that is an AC loop with the whole purpose being to cool things. It isn't a heat pump.
Are you implying an air-to-air heat exchanger? If you look at a front end tear-down, that's not how the system is arranged.
And the two coils in the HVAC refrigerant loop are the external condenser coils, that's where the heat from the HVAC system is shed to the outside air. The system isn't a heat pump, so supplying heat to those coils won't transfer anything to the cabin.
llavalle
Member
Here's a few other from my car. Sorry for the LONG post
Taken back in August. Outside temp was 4.0C (40f).
HVAC was off. Battery was pretty cold (between 9.5C and 12C) so the cooling loop was in series with the drive unit (basically heating the pack from the heat of the DU). You can confirm that by checking the 2 temps.
-Just under "Battery Heater" (which is off in that pic), 17.5C entering the pack (this screen is animated, trust me on the flow direction)
-Left side, out of the pack and 2nd pump, 14.6C.
i.e. Coolant gets cooler as is go through the batteries. Note that the top right valve is bypassing the center radiator at 100%
Another one, taken in December. A lot colder outside. Battery pack is REALLY cold, almost below freezing. -15C outside (5F). System is running the pack heater and the cooling (well, heating in that case) loop only goes though the pack, the DC-DC and the Heater. It bypasses the chiller (that's the heat exchanger from the AC and the battery loop when supercharging)
And here's the raw data :
You can see that the PTC heater (that's the cabin heater) is running at 90% capacity. Outside air is at -15.6C but evap temp is -12C because AC is actually working in COOLING mode to dry the air. Note that in that mode, the AC compressor pulses on & off so that pic was taken when the compressor was at 0%
In all cases, the only time there is coolant in contact with the AC heat exchange is when the chiller is in use and the system runs. There are no coolant loop connected to anything inside the cabin. The only way to get heat is to use the PTC. The only way to get cold is to use the AC
Example of use of chiller during supercharging session :
EAC (AC compressor) running at 100%, both AC coil fans running at 100%, evap at 107.4. Chiller in use, pushing coolant at 28.6C in the pack.. cells steady at 41-45C. Pump running at 100%. Drive unit pump running at 0%.
llavalle
Member
Might be worth noting here : this thermal screen hasn't been updated in a long time so some of the stuff does not show in recent car like mine (85D).
Stuff like the front drive unit, the PTC and EVAP in the HVAC box. The text data is correct though
Found that interesting screenshot I took while driving a while back. You can see the actual AC loop working to cool the car. Pic was taken in summer.
Stuff like the front drive unit, the PTC and EVAP in the HVAC box. The text data is correct though
Found that interesting screenshot I took while driving a while back. You can see the actual AC loop working to cool the car. Pic was taken in summer.
llavalle
Member
I don't have hard evidence but from my testing, it seems to lower it around 18C. It's hard to give you a hard number because Tesla changed these a few times and it varies according to SOC.
e.g. at 80-90%SOC on my 85D, normal mode target heating is 8C. Switch to range mode and it's now -10C. i.e. With the pack at -10C, it won't turn the pack heater.
It's also worth noting that the passive cooling target also changes from 30C to 40C when driving in range mode. That means the car will wait until the pack hits 40C before opening up the valve to the front radiator (the center, passive one) instead of 30C. The Active cooling target stays the same though (around 50C).
When the pack gets really low (charge), the active heating target rises. In normal mode, it can get in the 20-25C or higher when you're at 5% or less. That's probably the reason for the pop up saying "consider charging now, you'll use more energy if it gets colder". If it's -25C and you're stretching it.. chances are the pack heater will kick in at low SOC.. that's a great way to get screwed!
Quick note #2 : when you plug the car in (supercharger or other), it changes the targets significantly. They probably use that to just force the pumps to kick in at full speed right away. Check the screenshot I took while supercharging :
Passive Cooling : 24C
Active Cooling : 27C
Active Heating : 21C
So basically, when you plug in a supercharger, it'll heat the pack until it gets to 21C. Then at 24C it uses the front radiator and at 27C the AC kicks int. The range of temperature is a lot tighter.
edit : forgot to mention.. the car is tuned for efficiency to the minutes details. When the battery pack sits between the Passive and Active cooling target, it does not simply open up the valve to the radiator and runs the pumps full speed. It actually modulates the pump speed according to the speed you're driving. On the highway, they will run 100%. Slow down and they slow down : no need to circulate the coolant at full speed since the passive radiator is not very effective at low speed.
It also open and closes the louvers in the front bumper. Get stuck in traffic and the AC is running? if the evap gets too hot, it will open them up. Get some speed and the close and the fan speed adjusts.
Still important to know because I could potentially cold soak the pack at -20C, then not take into account half an hour of pack heating to get back to any charger, that could be like a 10 mile drain on top of everything else i.e. no regen, cold tires, cabin heatup.
IMHO compensating for the delta T from the inside of the cell to the sensor while supercharging.
Well at $0.06/kWh and 100% hydroelectric power, I think it makes sense. The issue of heat pump vs non-heat pump is also related to cold tolerance. I keep my house cooler than most people (58-62 F) and don't really use heat until the outside temperature dips below 30-40. The house also has a huge thermal sink (basement) that keeps things remarkably stable. Our 2011 Leaf without heat pump uses up to 5 KW to heat slowly and poorly. A friend's 2013 heats immediately and with about 1/4 the KW. Our 70D heat is "better" than our Leaf, but I wouldn't say it's great. Tesla definitely has more options on where to get heat, as well as more places to heat/cool than the Leaf. Comparing the two heating systems is difficult, but the ability to supercharge and the larger battery make the 70D our travel car with more mileage, while the Leaf get the majority of our trips and time.
llavalle
Member
Unfortunately, for some reasons, Tesla does not want anyone to have access to those read-only screen. I *think* you might be able to get access using the service subscription but it's only open to MA residents in the US.
The passenger compartment in the 2016 Leaf is 116 cf, the Model S is 120 cf. The cargo capacity with the seats up is 23.6 cf for the Leaf and Edmunds lists 31.6 cf for the Model S, but that may include the frunk. Though the frunk on 2016 Model Ss is tiny.
For the 2012, Edmunds says the Leaf's cargo space is only 14.5 cf (seats up) and the interior volume 112.8 cf.
The passenger compartment volume figures can be misleading for many purposes, but for heating calculations they probably are useful.
In any case, the volume of the passenger compartment is similar between the Model S and Leaf, but the cargo area is about twice as large on the S vs the 2012 Leaf, though not as dramatically bigger on newer models of the Leaf. With Tesla's fastback arrangement on the S, the back window is much larger and will radiate more heat upward than the Leaf. The Model S with the pano roof will also lose more heat to radiation than the Leaf or a solid roof Model S.
Glass is a good black body radiator/absorber. More glass means more heat radiation loss when you're trying to heat the car.
Lon12
Member
I was wondering what some of the components (Chiller, Battery Heater etc.) in the diagnostic screen actually look like. This site has quite a few of the components exposed:
Tesla Technology – TesLorean
Tesla Technology – TesLorean
I want to thank @scaesare and @llavalle for the diagrams, and thank AND apologize to @MP3Mike and @AWDtsla for questioning you.
I came to this thread thinking I had a heat pump, and that waste heat was used for cabin heat. Now I am more educated. Very sorry if I was an @$$ in trying to get real information, but there was a lot more misinformation than knowledge out there, and I just had no idea who to believe.
I came to this thread thinking I had a heat pump, and that waste heat was used for cabin heat. Now I am more educated. Very sorry if I was an @$$ in trying to get real information, but there was a lot more misinformation than knowledge out there, and I just had no idea who to believe.
The hatch storage area is seating as well - at least in my Model S. I pump heat back there.
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