Realistic EV Range Degradation and Prediction?

[lefty]

I'm sure it's buried in the fine print somewhere but is there a "rule of thumb" that says something like, "for every degree drop in temperature you should expect x% degradation in range "? I realize it's not that simple but would be curious if there is something directional that exists?
Until this year I was unaware of how the cold affected battery performance. I split my time between MA and VT in the winters and VT can get brutally cold. It's usually not a sustained cold but would really like to know if I buy a Scout that claims to have X mile range, is it really X-100 miles if the temperature is 5 degrees?
Alternatively, do EVs today have any predictive software where you can plug in your truck model, tire size/type, expected passenger weight and expected temperature to estimate range?

 

[Jamie@ScoutMotors]

There likely are some rules of thumb, but too many variables for it to be consistent - the type of battery composition, size of the battery pack, software, heat pump or no heat pump, type of battery enclosure and temperature regulation, and on and on.

There have been a lot of headlines over the last two weeks, and a few things are clear:

1. Batteries have an optimum operating range, both hot and cold. Cold affects it more, but it isn't linear in terms of the degradation.
2. Battery pre-conditioning mode (bringing the battery pack into an optimum temperature range) is vitally important when temperatures are at extremes.
3. Not all EVs can pre-condition automatically - some are manual. Newer vehicles have incorporated this, but not all, forcing the burden on the consumer who is still learning the ins and outs of EV ownership to activate it manually.
4. Waiting till you only have 20% left in -15-degree weather and expecting to run heat full blast probably isn't going to work.
5. Charging stations need to mature to deal with extremes and software.

Clearly, people living in Alaska, Canada, Finland, Norway (especially Norway, where 84% of new registrations were EVs last year), and other locations where temperatures regularly dip below 0 degrees have been dealing with this for a while, with very few issues. They essentially have learned how to operate their cars in those conditions.

So, growing pains for sure, as we all expected.

 

[R1TVT]

1. In cold temps, and if you have a long-haul planned from your homebase (assuming you have a charger at home), one of the best ways to prepare the battery for cold weather performance is to precondition - starting a charge session shortly BEFORE you leave is actually the best way to do this. SIZE of the battery and how fast it will accept a charge will also be a big factor here.

2. My typical "performance window" in cold temps drops under 2 mi/kWh, which generally is where my R1T sits on AVERAGE. Factors include temperature, elevation gain, headwind, accessories, wheels, and in my case a heavier set of Nokian Hakka LT3 tires in winter. Realistic cold weather performance facing a headwind on the HWY and a gradual climb fall in the 1.3 mi/kWh for my truck. Realistic cold weather performance on a long, very slight descent with a tailwind can put me around 1.8 mi/kWh. This is full HWY SPEED (always hovering around 80MPH).

3. None of the degradation really impacts longer trips very much, because the truck, the SW the U/I are all very realistic in terms of actual consumption and range (dynamically) as you drive in the Rivian. You have a VERY GOOD IDEA for your trip and when you will need to charge.

4. #5 listed above by Jaimie is the single biggest factor in making life easier for EV owners in temperate climates and in areas where there are cold temperatures and mountains. There simply isn't enough good charging infrastructure in the places where it is needed for adventures in the Northeast. Maine and NH are DCFC wastelands once you get outside of the Mass commuting belt / Mass border area. Good news is Vermont is better. However, if you can't go somewhere and plug-in when you get there, you need to plan ahead for how much range you will need to get back to wherever you will be able to charge AFTER your adventure or drive... This requires forethought and some planning. It will get better...

I have captured a lot of this in screen shots in a lot of different conditions, here is one example. 81MPH in favorable winter conditions and no headwind.

 

[JohnnyScout]

Range and recovery are tge two biggest factors even in normal temperatures. How many kW does an average EV use over its anticipated range and is there any situation where an on-board generator (even hydrogen powered) could keep up with the power consumption of the EV driveline?

It's just a wild thought of throwing a genset in the bed tied into the charging system to extend range. While an environmental compromise remember that many recharging stations get their electricity from natural gas fueled power plants. It is a long way from a fossil fuel free electric grid

 

[R1TVT]

You also need to remember though, that most charging will occur at home. Many EV owners realize faster paybacks on installation of home solar to help off-set their electric bill or outright generate their own electricity and store it.

 

[J Alynn]

1. In cold temps, and if you have a long-haul planned from your homebase (assuming you have a charger at home), one of the best ways to prepare the battery for cold weather performance is to precondition - starting a charge session shortly BEFORE you leave is actually the best way to do this. SIZE of the battery and how fast it will accept a charge will also be a big factor here.

2. My typical "performance window" in cold temps drops under 2 mi/kWh, which generally is where my R1T sits on AVERAGE. Factors include temperature, elevation gain, headwind, accessories, wheels, and in my case a heavier set of Nokian Hakka LT3 tires in winter. Realistic cold weather performance facing a headwind on the HWY and a gradual climb fall in the 1.3 mi/kWh for my truck. Realistic cold weather performance on a long, very slight descent with a tailwind can put me around 1.8 mi/kWh. This is full HWY SPEED (always hovering around 80MPH).

3. None of the degradation really impacts longer trips very much, because the truck, the SW the U/I are all very realistic in terms of actual consumption and range (dynamically) as you drive in the Rivian. You have a VERY GOOD IDEA for your trip and when you will need to charge.

4. #5 listed above by Jaimie is the single biggest factor in making life easier for EV owners in temperate climates and in areas where there are cold temperatures and mountains. There simply isn't enough good charging infrastructure in the places where it is needed for adventures in the Northeast. Maine and NH are DCFC wastelands once you get outside of the Mass commuting belt / Mass border area. Good news is Vermont is better. However, if you can't go somewhere and plug-in when you get there, you need to plan ahead for how much range you will need to get back to wherever you will be able to charge AFTER your adventure or drive... This requires forethought and some planning. It will get better...

I have captured a lot of this in screen shots in a lot of different conditions, here is one example. 81MPH in favorable winter conditions and no headwind.

View attachment 2206

Your insight is always valuable-thanks again for the time you spend educating us-it’s great!

 

[oldgeeksguide]

.
2. Battery pre-conditioning mode (bringing the battery pack into an optimum temperature range) is vitally important when temperatures are at extremes.
3. Not all EVs can pre-condition automatically - some are manual. Newer vehicles have incorporated this, but not all, forcing the burden on the consumer who is still learning the ins and outs of EV ownership to activate it manually.

It’s fine if preconditioning happens automatically, but I need a simple way to manually trigger it as well. If I’m driving and decide to stop at this place I know 20 miles up the road to charge (maybe I’m hungry, maybe I need to use the bathroom &c.) I don’t want to have to pull over and spend 5 minutes fiddling with a touch screen so I can convince the car to “automatically “ precondition.

 

[R1TVT]

If you use native route-planning, preconditioning can be "built-in"... Meaning that if your route is taking you to a DCFC, your truck will already know this and your distance to the destination. When you are about 30 mins or so from your destination and depending upon other variables, the truck can start preconditioning on its own. In my case, I get an on-screen notification telling me that this is happening. You can also start manually preconditioning in the Rivian app (in my case) by preconditioning the climate.

 

[RebelliousPeasant]

In my experience living in Canada where winter temps get down to as low as -40 on some days the range can drop by as much as half - HOWEVER - that is only on the coldest of days where the thermometer is below -30C! Normal winter performance when temps are between -10C and -20C the range hit is more like 20% or so at worst and assuming you do absolutely no cold weather mitigation.

A thing a lot of people either don't know or ignore is that there are many things EV owners can do in the winter to mitigate the impact of cold weather on the battery. Keep the vehicle in a garage or plugged in. When not in use if the car is plugged in it helps the battery management system keep the battery happy by trickling some energy into heating the pack. Preconditioning the vehicle while its plugged in is another huge benefit. Warming it up while it has access to mains power means you won't be using battery power to heat the cabin which not only saves winter range but also means you likely won't have to scrape the windshield too!

Also, it's important to remember that the impact on range is more severe for short trips rather than long trips. If you do a lot of short trips in the cold the car spends a lot of energy just warming itself up only to have you stop and let it cool down again. On a longer road trip the vehicle is able to warm up and stay warm thus making it more efficient so the range hit will be much lower. Don't assume city driving consumption numbers are transferrable to a road trip, they aren't.

Most EVs also have battery preconditioning before charging and a lot of the news reports recently seemed to ignore that and many of the owners they talked to appeared unaware of that extremely useful feature. Basically if you set a charger as the destination in the car's navigation system it will start to actively heat the battery pack so when you do roll up to the charger the car will charge at a higher speed and in a reasonable amount of time rather than spending precious minutes at the charger just heating up the battery so that it can maybe fast charge. Batteries need to be around 20C or so in order to accept high charging speeds and will use energy from a charger to actively heat themselves instead of charge the battery. Cold batteries don't like to charge so if you don't preheat the pack on the way to the charger you'll waste a lot of time (and money!) heating up the battery while it's plugged in.

 

[lefty]

Interesting stuff, guys. I appreciate your insight as I really have no working knowledge on EV tech.