JRP3
Hyperactive Member
Model S uses waste motor/inverter heat to warm the pack, probably not enough extra heat to provide much for the cabin. Remember one of the main benefits of an EV drivetrain is high efficiency, which means little waste heat.
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Indeed, and subject as well to cold wind blowing over it at high velocity, not to mention splashing from sub-freezing water/salt mixtures.
Something to consider as well, is that for the majority of people whose power doesn't come from mainly renewables, burning gasoline for heat is far more efficient and less carbon heavy than electric power generation, transmission, and battery storage.
JRP3
Hyperactive Member
I doubt there is any type of insulation that would be effective for a week, or even much more than a day or two.
Ha! you need to come to germany.
We have houses here that heat their houses with warm water that is kept in a big hot water tank(35,000liter at 70°C)They make the water warm in summer with solar heating. Such a tank only looses a degree or so in a week. Of course they use like 20cm insulation.
But vacuum insulation is like 5-10 more effective than rockwool. Only flaw here with vacuum insulation is that it is stiff(not bendable and cost 80€/m²)
They dont need any additional energy. fully solar heatd.
Vacuum insulation looses 0,73 W/m²K (10mm)
So at 20° delta T one m² loss is only 14Wh/m²
Surface of tesla battery? 10m²? 140W loss per hour. How much uses Model s now,if anything?
Question is , would it be worth it to spend 140W of power to an e-car if it stands over night plugged in or over a wireless pad.
Maybe.....
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JRP3
Hyperactive Member
Since you aren't going to store water in a huge super insulated tank in a Tesla it's not a relevant technology.
If the car can be plugged in over night then I believe it will keep the battery heated to some degree anyway.
If the car can be plugged in over night then I believe it will keep the battery heated to some degree anyway.
Resurrecting this conversation since I'm still shell-shocked from the 1,800km drive in -20ºC from PEI to Toronto. Fredericton to Ottawa is 1,000km and took almost 17 hours - 70% more than a comparable ICE trip. This is unacceptable to the majority of the population and we must find a solution if we want EVs to flourish. Happy to share some additional data from Teslafi for the curious.
My take away from this brutal drive was that we can rule out the following "solutions" to the extreme cold weather problem:
- bigger batteries -- part of a solution, but not much good as an economic argument since you may only need the extreme cold weather solution 3 weeks a year and batteries are expensive. And you have to haul around the batteries all year, adding weight.
- more Supercharging -- part of the solution, but stopping to Supercharge for 30 minutes per 90 minutes of driving is the worst.
- faster Supercharging -- you can't charge cold batteries, period. Warming them up eats up time and/or range. Faster Supercharging does nothing for a battery that is at a high state of charge and is tapering, but it does ensure there's enough power to also run pack and cabin heaters - which I found out the hard way is really not the case with Urban SCs. Faster Supercharging plus bigger batteries would have helped certainly but the real kicker is the increase in consumption due to having to warm the cabin.
- even destination charging has a tough time keeping up. A cold soaked battery on a 48A (rare!) L2 charger takes over an hour to meaningfully heat up at -20ºC. And I'm afraid that 30A L2 chargers are more so the norm. If you don't have destination charging at -20ºC, GOOD LUCK.
I'd love the option to place a small heater in the frunk inline with the liquid loop of either the battery or the cabin, that accepts readily available propane canisters. Similar to the Volvo heater, but without the risk of a liquid fuel spillage.
Such an option will be that much important for the Tesla Semi.
My take away from this brutal drive was that we can rule out the following "solutions" to the extreme cold weather problem:
- bigger batteries -- part of a solution, but not much good as an economic argument since you may only need the extreme cold weather solution 3 weeks a year and batteries are expensive. And you have to haul around the batteries all year, adding weight.
- more Supercharging -- part of the solution, but stopping to Supercharge for 30 minutes per 90 minutes of driving is the worst.
- faster Supercharging -- you can't charge cold batteries, period. Warming them up eats up time and/or range. Faster Supercharging does nothing for a battery that is at a high state of charge and is tapering, but it does ensure there's enough power to also run pack and cabin heaters - which I found out the hard way is really not the case with Urban SCs. Faster Supercharging plus bigger batteries would have helped certainly but the real kicker is the increase in consumption due to having to warm the cabin.
- even destination charging has a tough time keeping up. A cold soaked battery on a 48A (rare!) L2 charger takes over an hour to meaningfully heat up at -20ºC. And I'm afraid that 30A L2 chargers are more so the norm. If you don't have destination charging at -20ºC, GOOD LUCK.
I'd love the option to place a small heater in the frunk inline with the liquid loop of either the battery or the cabin, that accepts readily available propane canisters. Similar to the Volvo heater, but without the risk of a liquid fuel spillage.
Such an option will be that much important for the Tesla Semi.
JRP3
Hyperactive Member
The majority of the population will never make such a trip so the solution has a very small target market.
One thing which would help the battery issues would be pack insulation. At this point the pack is just a bare metal housing exposed to the high speed air flowing under the vehicle drawing heat out at a high rate. Even a half inch of good insulation on the bottom would help a lot, an inch even better.
Disagree. Ontario, Quebec, and many north Eastern US states have been gripped with -20°C or worse conditions the last few weeks. It does happen.
I awknowledge that driving 1,000km in a day is extreme but owning a car with a usable range of 200km in these winter conditions is unacceptable, IMO.
JRP3
Hyperactive Member
I never said it didn't, I said the market is relatively small. The weather you are describing is unusual, i.e. rare, in most locations. Taking extremely long trips is also a rare occurrence.
Yet you accepted it
mknox
Well-Known Member
I had a somewhat better experience travelling 900 km from the Chicago suburbs to the GTA on December 26th:
It was -22C when we departed, and my car had sat outside all night (for a couple of days, actually) not plugged in. It was so cold, in fact, that my daughter's Honda, in the garage, would not start and had to be taken to the dealer to "thaw out".
I had about 75% SOC and ran pre-heating for 30-40 minutes (again, just on the car's own battery power) before we set out. From there, I drove a relatively short distance to the Rolling Meadows, IL Supercharger. There it took over 2 hours to get the car from about 60% to 90%.
From that point on, however, things improved markedly. I just drove normally (speed limit, cabin heat at 22C, Range Mode off) and did the trip using the same charging stops I use in the summer: St. Joseph, MI, Lansing, MI, Port Huron, MI and Woodstock, ON for a top up before heading home.
The "warmest" it got on the whole trip was about -18C. It was so cold that on a couple of my stops, my doors and windows were frozen shut when we went to get out of the car!
I find my car does very well, consumption-wise, once everything is fully and completely warmed up. I basically drove from Supercharger to Supercharger and left the HVAC on (Camper Mode) while the car was parked and charging. I really am coming to believe that this is the most important element: get the car warmed up, and keep it warmed up.
My trip took about 2 hours longer than it does in the summer and that was completely due to that first charging stop. My daughter and son-in-law have recently moved and I had nowhere to plug in. Where they used to live (nearby) I had a 120v outlet and would generally leave with a full charge and drive straight to St. Joseph.
The general population seems to accept ICE cars that frequently don't start when its cold, and Tesla's sell quite well in the northern countries so I think this is not that big of an adoption issue.
The real problem is that you have to be very careful about planning a trip where there is no charging at your destination. Particularly if you need to stay for a few days and make a trip or two during the time. You may have plenty of charge to get to and from your destination, but can use a ridiculous amount just getting the car warmed up for a short trip in the middle of your stay.
The real problem is that you have to be very careful about planning a trip where there is no charging at your destination. Particularly if you need to stay for a few days and make a trip or two during the time. You may have plenty of charge to get to and from your destination, but can use a ridiculous amount just getting the car warmed up for a short trip in the middle of your stay.
There is no need to warm up the car for a short trip. Switch on range mode, keep your clothes on and direct cabin heating to windscreen with slow fan.
Range mode will likely stop pack heating (except extreme). And cut in half maximum cabin heating. Though this should be reduced further.
There is no point to warm up a cabin for 5-10 minute drive.
Tesla has a really lossy cabin. Roof glass should be totally covered with DIY insulation (which is held there with OEM sunshades for example). Rear door windows likely too, as they hardly get transparent anyway.
Range mode will likely stop pack heating (except extreme). And cut in half maximum cabin heating. Though this should be reduced further.
There is no point to warm up a cabin for 5-10 minute drive.
Tesla has a really lossy cabin. Roof glass should be totally covered with DIY insulation (which is held there with OEM sunshades for example). Rear door windows likely too, as they hardly get transparent anyway.
JRP3
Hyperactive Member
But if it's a short trip there is also no reason not to, nor is there any reason to switch on range mode or keep the cabin heat on low. Short trip means you don't have to worry about range.
Range mode doesn't have that big an effect on things, it only drops the temperature targets by 10 degrees. Just last night I was watching as the DC-DC converter kicked on and the car warmed the coolant (and presumably the battery) up by 20 degrees just to run it for a few minutes.
israndy
Supercharger Hunter
Reading about the record breaking Cannonball Run, they did it w/o running the heat to get there as efficiently as possible. Very exciting but they were freezing.
I found *this* thread after reading an article about adding gasoline heat to an EV.
This was a hydronic heater install, like an Espar. Then you don't need to use the electric element off the battery to heat the car.
I am curious about the battery heat in a Tesla, if a hydronic heater was used would you be heating the coolant that feeds the cabin only or are they combined to also heat/cool the battery pack?
-Randy
I found *this* thread after reading an article about adding gasoline heat to an EV.
This was a hydronic heater install, like an Espar. Then you don't need to use the electric element off the battery to heat the car.
I am curious about the battery heat in a Tesla, if a hydronic heater was used would you be heating the coolant that feeds the cabin only or are they combined to also heat/cool the battery pack?
-Randy
They are two separate loops, so you'd either need two separate heaters. For practical use, heating just the battery pack would probably do wonders if you make lots of short trips in the winter. Could just use the seat heaters and wear gloves instead.
That's what I've always imagined, just heating the battery quickly and unplugged pre heating.
That would make a huge difference in cold weather driving. Short trips aren't where the issue is for us since the decreased range isn't really much of an issue. Where I've seen really major problems is when the car has been unplugged and cold soaked and we've had to drive a distance. The power loss in the first half hour is really startling and limits the car's utility.
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