Best temperature for battery health

[myoung816]

Now that we are in the middle of Autumn and the temps are cooling off a question on how the M3 battery is affected. Over the summer people discussed the affect the heat has on the battery pack, how the AC would need to cool the car.
How does the cool affect the battery? Is there a 'sweet spot' that is ideal for the battery?

 

[StellarRat]

From what I've read the lower the better, but I think anything under 90 F is OK. I know temps over 110 F kill them real fast without some kind of internal cooling system.

 

[gaswalla]

Seems like there are two temps: a temperature for max battery efficiency (is it 70F?) and another temp for good battery 'preservation' (cooler is better, but freezing is not good?)

 

[StellarRat]

Seems like there are two temps: a temperature for max battery efficiency (is it 70F?) and another temp for good battery 'preservation' (cooler is better, but freezing is not good?)

Actually, I don't think freezing hurts the battery, but it lowers the capacity while it's cold.

 

[SemiS3XYR]

you should keep it in a heated / conditioned garage like ALL THE TIME

keep it 60-90% and preheat the car on cold days. You'll be fine.

I can't comment on extreme heat days like AZ...
Genearally, do Tesla's from AZ, TX, etc get their batteries killed from the heat like the Nissan Leaf.

NJ isn't bad after all.

 

[StellarRat]

you should keep it in a heated / conditioned garage like ALL THE TIME

keep it 60-90% and preheat the car on cold days. You'll be fine.

I can't comment on extreme heat days like AZ...
Genearally, do Tesla's from AZ, TX, etc get their batteries killed from the heat like the Nissan Leaf.

NJ isn't bad after all.

I don't think so. Tesla's have a cooling system for the battery (I think.) Also, the Leaf batteries doesn't die from heat as easily any more. They changed the battery chemistry on the 2012 and up models to deal with the problem. I still don't think their batteries last as long as a Tesla though.

 

[SemiS3XYR]

Its the 2013 and up and it deals with problem but it's not a solution. I know cause I have a 2012 ha. It's been fine though. Only lost 2 bars and still gets me to work daily for the past two. I'm keeping good charging habits. 2012 are cheaper but if one were to buy one make sure to check battery health through leaf app and $15 bluetooth OBD device. 2013 also has the faster on board charger (double), heat pump, and the 'B' button. People hate on my leaf but best money I've spent on a used car (knock on wood).

 

[StellarRat]

Its the 2013 and up and it deals with problem but it's not a solution. I know cause I have a 2012 ha. It's been fine though. Only lost 2 bars and still gets me to work daily for the past two. I'm keeping good charging habits. 2012 are cheaper but if one were to buy one make sure to check battery health through leaf app and $15 bluetooth OBD device. 2013 also has the faster on board charger (double), heat pump, and the 'B' button. People hate on my leaf but best money I've spent on a used car (knock on wood).

My 2011 was down three bars when I got rid of it this summer (seven years of driving.) I was pretty disappointed in the battery life. I don't live in a hot climate either. I'm sure the Tesla will be much better. I've also read the new 150 mile Leafs are losing capacity rapidly that is a little disheartening as my sister just bought one. She couldn't afford a Tesla, BTW.

 

[Electric700]

All Teslas have liquid cooling / heating for the batteries, which is better than the air-cooled system Nissan uses in the Leaf.

Nissan also doesn't have any setting to charge to 90% or less (but Teslas do have this feature). So, the Leaf will normally charge to 100% unless the charge is manually interrupted first. I think this is part of the problem with battery degradation in the Leaf, so Nissan should really add the ability to set the charge level to 90% or less, and they need to add liquid battery cooling / heating. Also, the charge level feature requires just a software update, and I think it would help a lot.

 

[StellarRat]

All Teslas have liquid cooling / heating for the batteries, which is better than the air-cooled system Nissan uses in the Leaf.

Nissan also doesn't have any setting to charge to 90% or less (but Teslas do have this feature). So, the Leaf will normally charge to 100% unless the charge is manually interrupted first. I think this is part of the problem with battery degradation in the Leaf, so Nissan should really add the ability to set the charge level to 90% or less, and they need to add liquid battery cooling / heating. Also, the charge level feature requires just a software update, and I think it would help a lot.

My Leaf absolutely had an 80% setting.

 

[David99]

The problem is there is no idea temperature for the battery. Elon once said, the battery will last 'forever' for owners in Alaska, referring to how the cold temperatures make the battery last longer. Many studies have been made and show that keeping Lithium batteries cool will slow down degradation.
On other other side a cold battery doesn't perform well. It is inefficient and has a high internal resistance. The best performance and efficiency is around 40-55 Celsius. The chemical processes work better at higher temperatures. Unfortunately the 'parasitic processes' that cause degradation also work better at higher temperatures.

So we have opposing ideals. Cold is good for longevity, warm is good for efficiency and performance. What is Tesla doing with the battery? I monitored my Model S battery (through CAN bus data) for over 2 years now and here is what I found. If the car is parked, the battery temperature is not actively controlled by the car. The car never cools or warms the battery if the car is just parked and idle.

When driving, the car warms up the battery using waste heat from motor/inverter/DCDC converter. It is not really trying too hard, though. Whatever heat losses are coming from the mentioned components is used. If you drive slowly, this will be very little. If you drive fast/hard, the battery will warm up much quicker. Once the battery goes over 40 the car will stop using the heat from the motor. Of course using the battery (discharging or charging it) will cause some internal losses which will also warm up the battery itself. Especially when it's really hot outside and you are driving on the freeway, the battery can go up to 50 Celsius or more. Once it goes over that value the car will start using the AC to cool the battery down. As the battery temperature goes up it will use more and more AC power. I had a few situations driving in extreme heat in the desert and the car would tell me that it's reducing cabin cooling because it needs to cool the battery.

If the battery temperature drops below 8 Celsius, the car will use the battery heater (in the Model 3 it is using the motor as a heating element by running it less efficient on purpose). I assume using a battery below 8 C is not good and inefficient thus it's worth sacrificing energy to heat it up. So if you get in your car and the battery is very cold, you will see some serious energy usage in the beginning while the car warms up the battery. This only happens when the car is driving or you turn on the cabin heater (from the app). When the car is parked the car will not try to keep the battery warm.

I'm sorry if this got a little longer. I just wanted to outline what I found Tesla is doing with the battery in terms of temperature. Everyone can draw their own conclusions. It seem Tesla tries to keep the battery warm only when driving, but otherwise doesn't actively manage the battery temperature while the car is parked.

 

[StellarRat]

If the car is parked, the battery temperature is not actively controlled by the car. The car never cools or warms the battery if the car is just parked and idle.

That's interesting to me. I my understanding is that high heat is very bad for Li batteries. If you're right, I'm very surprised that Tesla didn't include some type of cooling to protect the battery. I could easily see a battery in car in Phoenix sitting on the black top reaching 120F - 130F in the summer.

 

[evJOULE]

Actually, I don't think freezing hurts the battery, but it lowers the capacity while it's cold.

Well it certainly lowers the capacity(rate) to charge quickly. My guess is that the biggest detriment to extremely cold batteries probably occurs when they are used. My personal preference is to avoid hard accelerations when first starting out in extreme cold temperatures to allow time for the battery pack to warm up.

 

[Kermee]

That's interesting to me. I my understanding is that high heat is very bad for Li batteries. If you're right, I'm very surprised that Tesla didn't include some type of cooling to protect the battery. I could easily see a battery in car in Phoenix sitting on the black top reaching 120F - 130F in the summer.

Just keep it under 140F, according to the Model 3 manual, and you'll be fine.

 

[StellarRat]

Just keep it under 140F, according to the Model 3 manual, and you'll be fine.

Ah ha! Well, I guess Tesla has the heat problem mostly solved then! That's good to know.

 

[Kermee]

Ah ha! Well, I guess Tesla has the heat problem mostly solved then! That's good to know.

Though, Model 3 is kinda screwed during a Mars winter...

 

[Electric700]

My Leaf absolutely had an 80% setting.

Yes, the original Leafs in the 2012 era did. Unfortunately, the new ones don't. They need to bring that setting back. Better yet, give Leaf owners a maximum charge level slider like Tesla has. It should default to 90% maximum after each charge.

 

[David99]

That's interesting to me. I my understanding is that high heat is very bad for Li batteries. If you're right, I'm very surprised that Tesla didn't include some type of cooling to protect the battery. I could easily see a battery in car in Phoenix sitting on the black top reaching 120F - 130F in the summer.

I think that's still a safe range for the battery. I have taken many long road trips in hot climates around CA, AZ, NV, TX. Driving fast and supercharging, the battery temperature is around 110-130 on average for the entire trip. I have done that for 50+ hours straight. So that's not something that is bad for the battery otherwise Tesla would cool the battery down more. That's why I assume Tesla doesn't see the need to actively cool the battery while it is just sitting there. It would take up a lot of energy to do that anyways. Keeping the cabin at 70 during a hot and sunny day takes up 10-20 kWh for a full 24 period. Even if we assume the battery needs less energy to be kept at say 80, it would still be 5-10 kWh every day. That's a lot of energy for a really small improvement in battery degradation.
Comparing old Tesla cars that have been driving in hot climates compared to those in cooler climates, the difference in degradation is small. Maybe 2% over 4 years. Just not worth wasting so much energy on. If it gets really really extreme, just turn on the climate control via the app and let it run. This will turn on the active battery cooling or heating. Charging the car will also activate the battery cooling or heating if needed. So as long as you drive and charging your car on a regular basis, there should be no worry.

 

[ewoodrick]

Now that we are in the middle of Autumn and the temps are cooling off a question on how the M3 battery is affected. Over the summer people discussed the affect the heat has on the battery pack, how the AC would need to cool the car.
How does the cool affect the battery? Is there a 'sweet spot' that is ideal for the battery?

Tesla has tried to design the battery system so that you don't have to worry about it. So first rule, don't worry about it so much. So many people seem to think that there are all sorts of "rules" and there really aren't any. Enjoy the car.

Yes, in colder temps, you will lose a little range, part of it is because of the heat, part is that batteries just don't like it. So the biggest thing to understand is that a trip you made in the fall and spring may not be able to be done in the midst of winter.

 

[evJOULE]

I wold like to think if you have a question about the high tech Model 3 you just bought, you should ask it no matter what it is. I appreciate the OP's question, and even if the answer is, no there is not a sweet spot temperature for the battery, the answer will have value to the person that asked it. I personally enjoy my car every day, and the fact that I might have questions about its functioning takes nothing away from that. The fact that I am interested enough to learn more about it, almost ensures that I will enjoy it longer.