# Preconditioning the battery for driving



## kenroginski (Mar 30, 2021)

Hi - Is preconditioning really important?
I saw a youtube video stating that it does not make a difference in energy saving but it is good for the life of the battery.

What outside temperature should I condition it at? What temperature is considered cold for the battery?

It was only 55 degrees outside. I turned on the climate to 70 degrees in advance until I received a message the cabin temperature was set. Upon driving the line at the top by the speedometer had dotted lines to the left which I believe means that there is a cold battery. I thought the cabin temperature would have warmed up the battery. I drove for 30 minutes and no change. However I did use autopilot for a short time and the dotted lines became solid. When turning off autopilot the dots reappeared. I’m very confused.


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## Rub"Y" (4 mo ago)

Dots on the left I believe means you have limited regenerative braking because your battery is fully charged.


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## Power Surge (Jan 6, 2022)

I've never seen dots on my energy driving line. And it was 45 degrees when I left the house this morning.


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## Ed Woodrick (May 26, 2018)

The top dots represent that the battery has a combination of too cold and/or too full and can't accept full regeneration. It's not bad, it just indicates that you won't be getting full regeneration when driving, be ready to use the brakes.
At 55 degrees, not much to worry about.
When the car is more like 10 degrees F, that's when warming the battery can help extend range.

NOTHING that I mentioned said anything about bad for the battery. There's nothing to worry about.

The thing to worry about when it starts getting cold is your range. You can expect about 30% degradation when it gets cool outside (starting around 50F). This is normal and expected. It happens to all batteries.


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## garsh (Apr 4, 2016)

Power Surge said:


> I've never seen dots on my energy driving line.


if you've turned on the option to use brakes when regen is restricted (I forget what it's called), then you won't see any dots.


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## garsh (Apr 4, 2016)

kenroginski said:


> Hi - Is preconditioning really important?


No. It just saves time when supercharging.

in order to supercharge at the fastest rates, the battery needs to be at about 90°F. If it's not warm enough, then initial supercharging will be slower until the battery warms up enough to accept faster charging.

Preconditioning just warms up the battery ahead of time so you can supercharge at the fastest rate right away.


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## francoisp (Sep 28, 2018)

garsh said:


> No. It just saves time when supercharging.
> 
> in order to supercharge at the fastest rates, the battery needs to be at about 90°F. If it's not warm enough, then initial supercharging will be slower until the battery warms up enough to accept faster charging.
> 
> Preconditioning just warms up the battery ahead of time so you can supercharge at the fastest rate right away.


In winter doesn't preconditioning the car before leaving yield better overall car efficiency because of better regen and better battery efficiency?


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## garsh (Apr 4, 2016)

francoisp said:


> In winter doesn't preconditioning the car before leaving yield better overall car efficiency because of better regen and better battery efficiency?


It doesn't increase efficiency. Doing so uses energy. For supercharging, heating the battery is going to happen anyhow. 

Warming up the battery does allow the battery to release more energy. It also allows the battery to accept more power - so stronger regen is possible.


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## francoisp (Sep 28, 2018)

garsh said:


> It doesn't increase efficiency. Doing so uses energy. For supercharging, heating the battery is going to happen anyhow.
> 
> Warming up the battery does allow the battery to release more energy. It also allows the battery to accept more power - so stronger regen is possible.


I meant that when the car is plugged in at home I was told that scheduling a departure time will warm up the car and the battery.


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## garsh (Apr 4, 2016)

francoisp said:


> I meant that when the car is plugged in at home I was told that scheduling a departure time will warm up the car and the battery.


Sure, but my understanding is that this increases available regen and available energy from the battery, but not efficiency - it uses more energy. It's a trade-off.


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## francoisp (Sep 28, 2018)

garsh said:


> Sure, but my understanding is that this increases available regen and available energy from the battery, but not efficiency - it uses more energy. It's a trade-off.


The question is can the expenditure of energy at home warming up the car battery be recovered with the increased regen in city driving conditions?


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## DocScott (Mar 6, 2019)

In terms of pre-heating the car and battery before driving, my belief is that it extends range but wastes energy.

In other words, there will be improved efficiency once driving, allowing you to drive further on that charge. But for energy usage that will be more than made up for by the energy wasted while the car is just sitting in the garage being heated up.

So if you expect to return home without having to charge again (your round trip is less than the range), I don't recommend doing this just for "efficiency." (Of course, it's nice to get into a car that's already warm for comfort.) But if you're about to head out on a road trip, it might be cheaper to pay for energy at home than to have to use a Supercharger. I think the savings is pretty small, because the battery will warm up pretty quickly while driving, but in theory at least it could save a few pennies.


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## Rub"Y" (4 mo ago)

francoisp said:


> The question is can the expenditure of energy at home warming up the car battery be recovered with the increased regen in city driving conditions?


Doubt very much, but you will gain comfort and better drivability . Small price to pay!


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## Power Surge (Jan 6, 2022)

garsh said:


> if you've turned on the option to use brakes when regen is restricted (I forget what it's called), then you won't see any dots.


Not familiar with that....


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## FRC (Aug 4, 2018)

Power Surge said:


> Not familiar with that....


In the car, under the pedals and steering tab, scroll down to regenerative braking and there is a toggle you can enable that allows the car to simulate the effect of regen with the brakes when regen is limited.


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## Power Surge (Jan 6, 2022)

FRC said:


> In the car, under the pedals and steering tab, scroll down to regenerative braking and there is a toggle you can enable that allows the car to simulate the effect of regen with the brakes when regen is limited.


I see it now. It's not enabled.


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## Ed Woodrick (May 26, 2018)

francoisp said:


> The question is can the expenditure of energy at home warming up the car battery be recovered with the increased regen in city driving conditions?


If I remember correctly, it's not the amount of energy in the battery that changes. For example, full battery at 70F and take it to 10F and your range is lousy. Bring the battery temp back up and you get the range back. But remember in the winter, you can basically assume that you are only going to get ~60%. 
It's a weird situation and it tends to be a lose-lose scenario.

Basic answer, warm the battery when plugged into power. (letting the car sit at 0F, not plugged in, isn't a smart thing. I'm not talking about EV's, I'm talking ANY car) and make sure that the car is warming before you travel is what you tend to want to do. 

That's why so many parking lots in the north have 120V plugs in them, to keep engine blocks warm.


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## Bigriver (Jan 26, 2018)

Ed Woodrick said:


> That's why so many parking lots in the north have 120V plugs in them, to keep engine blocks warm


I protest that you are writing with too broad of a pen… too many generalizations. I live in “the North” and have never seen a single engine block heater in a parking lot. I’ve heard of such a thing, but I think you have to go to the “Far North” to find.


Ed Woodrick said:


> But remember in the winter, you can basically assume that you are only going to get ~60%.


For below 0 F, perhaps that is about right. But I think most of us experience winter temps that are usually notable above 0 F. My actual hit in efficiency due to cold temps is not that dramatic.


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## Power Surge (Jan 6, 2022)

Bigriver said:


> I protest that you are writing with too broad of a pen… too many generalizations. I live in “the North” and have never seen a single engine block heater in a parking lot. I’ve heard of such a thing, but I think you have to go to the “Far North” to find.


Same here. Never saw or heard of that. Ever.


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## Rub"Y" (4 mo ago)

Seen them in Sherbrooke and Chicoutimi. But this was 30-40 years ago. Maybe even 50 for Sherbrooke.


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## francoisp (Sep 28, 2018)

I worked in Sweden in the late 90's and although it wasn't colder than Montreal I remember many people plugging their car while at work. In Canada I rarely saw that in my adult life. I think it stopped being much of a need with better engine oil for winter and injectors replacing carburators.


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