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Discussion Starter · #1 ·
Volvo wrote the following:

Updates from April 2021.
  • Preheating of the battery when charging to 90% and 100%, gives improved range. No preheating when charging under 90%.
Why would preheating the battery give improved range?
I can see that pre heating would give improved charge time and improved longevity of the batteries life but not range.

Is this maybe a typo from Volvo?

As it is written it implies that If you charge a battery to 90% with a preheated battery you will get more from that 90% than 90% that was charged without heating. This would mean 90%s are not all equal …

Maybe they are assuming that you will immediately use the car while the battery is warm …perhaps if you stick the car in a garage after a 90% charge that 90% becomes 89 or something?

What am I missing. My background is physics but I am not an electrical engineer and physics has also moved on since college :)
 

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They are talking about preheating the battery while preconditioning the car while it's plugged in to the wall. If you start driving in the cold, it has to heat the battery up so it will reduce your range. If they preheat the battery while the cabin is also heating up, by the time you get in and drive everything will be up to temp and no extra power is wasted. Why they decided only at 90% will it preheat the battery is beyond me. Seems like it's best to just do it regardless if the car is plugged in and preconditioning.
 

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There are two factors at play here. Using the battery to heat the cabin draws down power, so yes preheating the CABIN ahead of time on "shore" power (while plugged in) works out better in cold temps. However, there is also a drain to heat the battery top optimal temps. Read the article above, it explains this. Pre heating the battery pack itself has benefits.

This is why in many other EVs I've driven (Tesla, Porsche, etc) -- when you plug in that you are headed to a DC fast charger, it actually "pre conditions" the pack to RAISE the temp. Optimal DC fast charging is usually around 77F or above -- of course too hot is bad too -- but too low and you wont hit peak kW charging speeds. There are charts/studies that explain this deeper. Hope this helps!
 

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As a Tesla owner also, when I am on the road and chose a Tesla Supercharger from the mapping screen and mark that as my destination, depending on the distance/time to get to the charger, Tesla will begin to pre-condition my battery. If its warm outside, not so long before I get there but if its cold outside it will begin the process earlier.
 

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Discussion Starter · #5 ·

There are two factors at play here. Using the battery to heat the cabin draws down power, so yes preheating the CABIN ahead of time on "shore" power (while plugged in) works out better in cold temps. However, there is also a drain to heat the battery top optimal temps. Read the article above, it explains this. Pre heating the battery pack itself has benefits.

This is why in many other EVs I've driven (Tesla, Porsche, etc) -- when you plug in that you are headed to a DC fast charger, it actually "pre conditions" the pack to RAISE the temp. Optimal DC fast charging is usually around 77F or above -- of course too hot is bad too -- but too low and you wont hit peak kW charging speeds. There are charts/studies that explain this deeper. Hope this helps!
I agree with the pre heating the battery concept. There is one caveat. The blurb says it only does it for over 80… this seems more like it is a charge rate fix vs a get the battery ready to work proprietor as this would be relevant for any charge amount would it not?

The more I think about it the
 

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Discussion Starter · #6 ·
….the more I think they meant to say charging speed and instead put range. Maybe a translator issue or just a non technical writer issue.
 
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Discussion Starter · #7 ·
As a Tesla owner also, when I am on the road and chose a Tesla Supercharger from the mapping screen and mark that as my destination, depending on the distance/time to get to the charger, Tesla will begin to pre-condition my battery. If its warm outside, not so long before I get there but if its cold outside it will begin the process earlier.
I had heard about Tesla’s doing this. Which is very nice. Again though this sets up charging speed not battery range.
 

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Maybe I wasn't very clear. This has nothing to do with faster charging of the battery. If the battery of the car is cold when you start driving, it must heat the battery up to operating temperature. A cold battery is limited in power delivery and regeneration. If your car is plugged in at 90% and you have requested to precondition the cabin, the car will also use the energy from the wall to preheat the battery. Using power from the wall to do this before you leave instead of the battery during driving increases your range.

Selecting a DCFC destination in navigation may or may not also precondition the battery for faster charging but that is a separate issue.
 

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Discussion Starter · #9 ·
Maybe I wasn't very clear. This has nothing to do with faster charging of the battery. If the battery of the car is cold when you start driving, it must heat the battery up to operating temperature. A cold battery is limited in power delivery and regeneration. If your car is plugged in at 90% and you have requested to precondition the cabin, the car will also use the energy from the wall to preheat the battery. Using power from the wall to do this before you leave instead of the battery during driving increases your range.

Selecting a DCFC destination in navigation may or may not also precondition the battery for faster charging but that is a separate issue.
I did understand your logic. I think though that the same logic would apply to 70% charge or 80% charge whereas it is stated that this is not done for anything lower than 90% which would be more in line with heating the battery so it charges faster at those percentages. Level 3 gets slower as the battery is close to full.

As to warming the battery so that when you drive off it is the correct temperature. From my experience charging the battery is exothermal and the car has had to cool the battery after a charge vs it still being cool when you drive off.
 

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I did understand your logic. I think though that the same logic would apply to 70% charge or 80% charge whereas it is stated that this is not done for anything lower than 90% which would be more in line with heating the battery so it charges faster at those percentages. Level 3 gets slower as the battery is close to full.

As to warming the battery so that when you drive off it is the correct temperature. From my experience charging the battery is exothermal and the car has had to cool the battery after a charge vs it still being cool when you drive off.
I'm talking level 2 charger during winter. Your car might already be fully charged but still plugged in during the preconditioning. I agree it doesn't make sense that it would only be at 90% but I gotta assume that's what they are talking about. Just the act of charging at a DCFC station heats the battery already. By the time you are going slow at 90% the battery should be plenty hot. Either there is a really weird translation issue or it's something like what I think.

Perhaps they say 90% because that's their recommended charge level and what they really mean is: if the car is at your desired charge level already, the battery will be preheated while preconditioning. But if the car is under the desired charge level, it will use all the power to continue charging rather than syphon off some power to preheat the battery also.

That's my best guess anyway. I was reading some google translate forums from people in Europe who had the car during winter that complained about high consumption on short trips. Seems like this would alleviate that some.
 

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Discussion Starter · #11 ·
I'm talking level 2 charger during winter. Your car might already be fully charged but still plugged in during the preconditioning. I agree it doesn't make sense that it would only be at 90% but I gotta assume that's what they are talking about. Just the act of charging at a DCFC station heats the battery already. By the time you are going slow at 90% the battery should be plenty hot. Either there is a really weird translation issue or it's something like what I think.

Perhaps they say 90% because that's their recommended charge level and what they really mean is: if the car is at your desired charge level already, the battery will be preheated while preconditioning. But if the car is under the desired charge level, it will use all the power to continue charging rather than syphon off some power to preheat the battery also.

That's my best guess anyway. I was reading some google translate forums from people in Europe who had the car during winter that complained about high consumption on short trips. Seems like this would alleviate that some.
interesting I had assumed the high power usage during the winter was caused by them having the heating on, de icing and just keeping the battery warm whilst driving. In their bitter cold conditions I find it hard to imagine any warmth remaining for long without active heating. Heat in the winter being the only Handy by product of an ice engine.

I am still betting Volvo had a typo :p but if not anything that helps the car be more efficient is good.

Got a 14 hour drive coming up. Hopefully it is a breeze and not too exciting :p

Hopefully I will not end up asking questions on here during the trip due to it going terribly wrong :p
 
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