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[strider]

Thank you all for the responses on my post It's one of those questions that have been bugging me for a while and I couldn't really get decent answers from other forums.

Another question if I may ...
How do EVs handle day long driving and parking in sub-freezing temps (so sustained 10-30 degrees farhenheit)? Say we drive ~100 miles or so to go skiing, are we going to have enough juice to drive back in the evening?

On ICE vehicles the 12v battery is often the weak point in cold conditions, I would assume that would also be a weak point for EVs right? Can you jump start the 12v on an EV to get things going like you can on an ICE vehicle?

Yes, you can "jump" the 12V in EVs. In the Tesla there are leads behind a panel in the front bumper to which you apply 12V and it powers up the computers so you can open the doors, frunk, etc plus (most importantly) close the High voltage contactors (fancy name for the big relay(s) the connect the high voltage (big) battery to the car). A small jump pack is plenty to do this. The only wrinkle being (at least with a Tesla) you can't open any part of the car without power because all of the openings are electrically operated so you will need to borrow a jump pack (or old school jumper cables and a friendly driver) to get into the car.

Once the contactors close the HV battery will charge the 12V. Also, the car will warn you when the 12V starts getting weak so you can replace it ahead of time. Tesla's used to eat 12V batteries but they have gotten much better. My wife's is 8 years old now and going fine. Mine is 4 years old but it is Li-Ion (Tesla decided to just make their own instead of buying 12V lead acid).

The car won't lose a ton of range sitting in that that 10-30F range, plus it will be warm for some time after you park it. So a day of skiing would probably be fine, especially because you are likely going downhill on the way home. That being said, batteries don't like to charge or discharge when cold. The car will have to use some charge to heat the batteries (and the cabin) so your initial draw (efficiency/range) will look terrifying until everything warms up. I'm sure that Scout will use a heat pump so once you get rolling and the motors and battery start generating their own heat it will be able to use that heat for the cabin and such.

Ideally you would plug in for the day but I know that chargers are pretty limited. Heck, if they kept all those 120V outlets for block heaters from back in the day that would help.

 

[BeerParty]

Thank you all for the responses on my post It's one of those questions that have been bugging me for a while and I couldn't really get decent answers from other forums.

Another question if I may ...
How do EVs handle day long driving and parking in sub-freezing temps (so sustained 10-30 degrees farhenheit)? Say we drive ~100 miles or so to go skiing, are we going to have enough juice to drive back in the evening?

On ICE vehicles the 12v battery is often the weak point in cold conditions, I would assume that would also be a weak point for EVs right? Can you jump start the 12v on an EV to get things going like you can on an ICE vehicle?

I am going to answer your last question first - you don't need to worry about the 12V battery losing charge (in any weather conditions) in an EV. The 12V battery in a ICE vehicle will lose charge because it only gets charged when the car is running. That's not the case in an EV. In an EV the traction battery (aka high-voltage battery) will maintain the charge of the 12V battery even if the car is not turned on. So as long at the main battery in an EV has sufficient charge, the 12V battery will be fine.

 

[BeerParty]

Thank you all for the responses on my post It's one of those questions that have been bugging me for a while and I couldn't really get decent answers from other forums.

Another question if I may ...
How do EVs handle day long driving and parking in sub-freezing temps (so sustained 10-30 degrees farhenheit)? Say we drive ~100 miles or so to go skiing, are we going to have enough juice to drive back in the evening?

On ICE vehicles the 12v battery is often the weak point in cold conditions, I would assume that would also be a weak point for EVs right? Can you jump start the 12v on an EV to get things going like you can on an ICE vehicle?

Now, to answer your first question. An EV is not as efficient in cold weather, that is true. But it isn't as bad as the detractors will claim. One of the issues is that an ICE vehicle will use excess heat from the engine to warm the cabin. An EV doesn't have that "free" heat, so it will have to use battery power to heat the cabin. The initial part of a trip in an EV will have worse efficiency because of the power draw to warm up the cabin. Once the cabin is warm, the efficiency will get better since it just has to maintain the temps in the cabin, but it still won't be as efficient as when you don't need the heat. The other major issue is that batteries are not as efficient when they are cold, but as others have already pointed out, that is mediated in modern vehicles.

Your vehicle will estimate the available remaining range, and it will have data from the previous drive, the current drive, and sensor data (including temps) to use in that calculation. So the vehicle will be able to tell you how far you can go before needing to recharge. I don't know how specific your 100 miles one-way trip example is, but since most mid to high-end EVs have a range of about 300 miles, a round trip of 200 miles (even in cold weather) would not require a charging stop.

 

[BeerParty]

I don't have an EV yet, so I am wondering if this is an acceptable way to charge? I've been reading that it is recommended that EVs should be operated from 20% to 80% of battery. My driving can be highly variable with spur of the moment trips of considerable distance. Add to that I live in Northern Wisconsin/ UP Michigan where fast charge stations are quite rare. If I were to get an EV I think I would be tempted to charge full up at home every night 'just in case'. Would that be a bad thing ... or would the range extender be a better choice for me?

Others have already answered this for the most part, but there is one aspect I don't think anyone has mentioned. The main situation for the 20% to 80% "rule" is when you are on a road trip and DC fast charging. But that rule is mainly about efficiency.

Most vehicles these days have a charging curve, and they charge fastest when the battery is between 20% and 80%. Once the battery level gets above 80% the vehicle decreases the power and the charging rate slows down. That's why companies always use 20% to 80% when they quote charging times. What they don't advertise is that when DC fast charging above 80%, the charging rate will drop substantially. In my Ioniq 5, on a DC fast charger that last 20% (from 80% to 100%) will take about 4 times as long as the 20% to 80% charge time.

So the recommendation when on a road trip is to plan your stops so you only need to charge up to 80% between stops. That way you will always be in the sweet spot for charging speed. It's faster that way. For example, when I road trip in my Ioniq 5, my charging times are almost always based on how long it takes me to use the restroom and get a drink/snack. By the time I get back to my car, the charge is already over 80%. I don't wait, I can reach my next stop easily with an 80% charge. It is faster to only charge to 80% and add one extra 15 minute charging stop than it is to charge to 100% each time and extend each leg to the car's maximum range.

BTW, at highway speeds that 80%-20% drive is between 3.5 to 4 hours, which is the same range I typically did between stops in my RAV4 hybrid. So I am not stopping any more frequently or for longer when I road trip my Ioniq 5 instead of my RAV 4.

 

[SpaceEVDriver]

Thank you all for the responses on my post It's one of those questions that have been bugging me for a while and I couldn't really get decent answers from other forums.

Another question if I may ...
How do EVs handle day long driving and parking in sub-freezing temps (so sustained 10-30 degrees farhenheit)? Say we drive ~100 miles or so to go skiing, are we going to have enough juice to drive back in the evening?

On ICE vehicles the 12v battery is often the weak point in cold conditions, I would assume that would also be a weak point for EVs right? Can you jump start the 12v on an EV to get things going like you can on an ICE vehicle?

I don’t drive in very cold temperatures, so I can’t answer from personal experience.

I can say that being stuck in snow storms for long periods of time works out much better for EV drivers than for ICE drivers.

The only reason I could imagine changing back from BEV to hybrid is if I lived in extreme cold (below 0 F for weeks at a time). And even then, the engineering would have to be done right to make it worth going back. I’d probably still not go back.

If I were leading the Harvester's engineering for cold weather performance, I would make standard a package that included the ability to warm (or cool) the ICE by pumping electrically-heated (cooled) fluids through the heat pump into and through the ICE engine block. So someone who lives in very cold areas could tell their Harvester to warm up at 03:00 for departure at 05:00. Instead of starting the ICE engine and suffocating everyone with carbon monoxide, the truck would know to just run the heat pump to heat the battery and the ICE engine block. Then when it’s time to drive, the engine will already be at its ideal temperature, the battery will be warmed, and the cabin will be warmed. That would increase efficiency during a drive substantially.

We don’t know anything about the Scout EREV engineering right now other than some vague hints.

 

[SpaceEVDriver]

Another point about charging:

If you never charge to 100%, your battery management system WILL eventually get out of sync with reality. This is because there’s an inaccuracy in counting how much energy flows into and out of the battery.

The consequences can range from bad estimates for range to poor performance from a bad estimate of the true energy stored in the battery.

About once a quarter to half-year or so I run the battery down to close to 0% and then charge to 100% without driving the vehicle. This resets the BMS so it knows how much energy it can really store in the battery.

 

[SpaceEVDriver]

Others have already answered this for the most part, but there is one aspect I don't think anyone has mentioned. The main situation for the 20% to 80% "rule" is when you are on a road trip and DC fast charging. But that rule is mainly about efficiency.

Most vehicles these days have a charging curve, and they charge fastest when the battery is between 20% and 80%. Once the battery level gets above 80% the vehicle decreases the power and the charging rate slows down. That's why companies always use 20% to 80% when they quote charging times. What they don't advertise is that when DC fast charging above 80%, the charging rate will drop substantially. In my Ioniq 5, on a DC fast charger that last 20% (from 80% to 100%) will take about 4 times as long as the 20% to 80% charge time.

So the recommendation when on a road trip is to plan your stops so you only need to charge up to 80% between stops. That way you will always be in the sweet spot for charging speed. It's faster that way. For example, when I road trip in my Ioniq 5, my charging times are almost always based on how long it takes me to use the restroom and get a drink/snack. By the time I get back to my car, the charge is already over 80%. I don't wait, I can reach my next stop easily with an 80% charge. It is faster to only charge to 80% and add one extra 15 minute charging stop than it is to charge to 100% each time and extend each leg to the car's maximum range.

BTW, at highway speeds that 80%-20% drive is between 3.5 to 4 hours, which is the same range I typically did between stops in my RAV4 hybrid. So I am not stopping any more frequently or for longer when I road trip my Ioniq 5 instead of my RAV 4.

Thanks @BeerParty, I meant to mention this as well and then got distracted.

I usually don’t go below about 10-20% on a road trip. This is so I can change my mind about which charger I’m going to use.

Previously I used to charge up to less than 85% unless I really needed the charge. Now I’ll stop charging anywhere from 70% to 90%. The Silverado charging curve is fantastic. At 80%, it drops to 100 kW. At 95%, it’s finally down to about 50 kW. At 70%, I can get 3-3.5 hours of freeway driving (down to 20%). Unless I am towing or I have a major concern about the next several chargers, I don’t need to pay for more than 70% DCFC. I’ll charge overnight on L2.

 

[J Alynn]

Thank you all for the responses on my post It's one of those questions that have been bugging me for a while and I couldn't really get decent answers from other forums.

Another question if I may ...
How do EVs handle day long driving and parking in sub-freezing temps (so sustained 10-30 degrees farhenheit)? Say we drive ~100 miles or so to go skiing, are we going to have enough juice to drive back in the evening?

On ICE vehicles the 12v battery is often the weak point in cold conditions, I would assume that would also be a weak point for EVs right? Can you jump start the 12v on an EV to get things going like you can on an ICE vehicle?

Hoping @R1TVT chimes in here as he is NE area and does a lot of skiing and wi there activities-he’ll be a great reaource

 

[R1TVT]

Did someone say cold weather?

The coldest temps I see when winter driving are about -20F (extreme). This past year, the coldest temp in VT was -29F in the town of East Haven (Northeast Kingdom of Vermont near Jay Peak). That is pretty impressive cold considering that the coldest temp on Mt Washington was -31 on Feb 6 (with the coldest wind chill reported on the summit at -92F on Jan 24. Good news is that most people aren't driving around much in that.

Most of my winter driving starts in the single digits, and usually warms into the 20's over the course of the day. Wind and cold has a heavy impact, so if you are traveling uphill into a headwind in ski country gaining elevation, in single digits, in a truck, on dedicated snow tires (Nokian Hakkas LT3s in my case), you are GOING TO TAKE AN EFFICIENCY HIT. Same in an ICE vehicle of course, BUT the trick is just having enough juice left at your destination to either get you somewhere to slow charge overnight or to get back to a DCFC. This was much harder when I first bought my truck in 2022, but much easier now (infrastructure has improved in ski country in the NE).

As others have said, preconditioning in winter is very helpful. If your battery is a cold brick and needs to warm up, you will see a range number that may be lower than your actual range once your numbers adjust and your battery is done preconditioning. That is the great thing about good SW - you will get real-world feedback on efficiency in real time. If you start driving like a maniac, your range will reflect that.

So, the real question is what will efficiency look like? Because based on your efficiency and the size of your battery, you can understand the real range you will see at different speeds over different intervals or under different conditions. Once you hit 80 in the cold on the HWY, you are going to be impacted more quickly. When traveling for skiing, for example, the trip to the mountain in the cold dark morning going uphill is always worse. Leaving a ski area is generally down hill and if you get a tailwind your return numbers can be DRASTICALLY different in the afternoon.

I did some initial screen captures under different temps and different driving conditions early on, but now I know my routine, I tend to charge 2/3 of the way to my destination and grab a coffee, and I don't worry about the numbers (because I know what they will usually be and over a long distance, I am going to stop and get some juice no matter what the circumstance). Here are a few examples from early days with my Rivian in its first winter. And this was before BMS and OTA SW updates that Rivian dropped to help improve cold-weather efficiency. Drive modes can also impact range of course:

TEST 1: 80 MPH at 20F on Nokian Hakka LT3's (slightly heaver than the 20 AT's) light headwind, gaining about 2000 vertical feet very gradually so no monstrous hills, in CONSERVE MODE: 1.26 mi/KWh average. I was watching to see what speed impacts would have over 75 (based on miles remaining at destination), and a good guess would be that you will lose 5 miles of range for every 5 mph over 75MPH you drive over the course of an hour.
EFFICIENCY RESULT = 1.26 mi/kWh AVG over 15 mins (*HIGHER SPEED HURTS)

TEST 2: 30-40 MPH at 20F on Nokian Hakka LT3's - slower speed, on snow covered roads (in SNOW MODE), ascending a very long & steep gradient for 3 miles:
EFFICIENCY RESULT = 1.55 mi/kWh AVG over 15 mins (*LOWER SPEED HELPS EFFICIENCY IN TOUGH CONDITIONS)

TEST 3: 81 MPH at 20F on Nokian Hakka LT3's - Higher speed with gradual descent & slight tailwind, in CONSERVE MODE (*2 motors) 20F.
EFFICIENCY RESULT = 1.77 mi/kWh avg over 15 mins (*could be over 2.0 with slightly slower HWY speeds)

TEST #4 - Park at the ski area chargers. FAILED>>>

 

[R1TVT]

Taking real-world data from your driving, then plugging that data in to a model to look at results, can validate and predict what you will be seeing for actual ranges. So in one of my cases where my efficiency was at 1.47, and with the following variables assumed, and leaving my house at 100% SOC, with an avg temp of 20F, and gaining 2K feet in elevation at 80MPH, I should see somewhere around 191 miles of range in my truck with a Large Pack battery (as one example).

 

[J Alynn]

So great we have @SpaceEVDriver who covers desert driving and @R1TVT covering winter. Love it!