Preheating Battery Importance

[troopercooper]

I've seen a few people mention the preheat of the battery, especially if its below 10C. I've never really thought about how important this is until stumbling across this video that was recently uploaded.

For those not wanting to watch, the Tesla M3 has 35% of battery when pulling into the Supercharger and it takes about 45 minutes of battery preheating before the car will accept any juice - stressing the importance of preconditioning your battery in extreme conditions. As a new EV owner, this was unexpected but good to know.

Worth noting that in the video location, its -26C.

 

[PristDean]

What are the benefits of preheating / battery conditioning, apart from the above?
Better range on a cold day before you set out ?

 

[Sloucher]

By pre-heating the battery, it will accept charge more readily (read quickly) and allows the battery to accept more charge when the outside temperature is low.

 

[troopercooper]

What are the benefits of preheating / battery conditioning, apart from the above?
Better range on a cold day before you set out ?

From what I gather, preheating the battery before a trip will improve its efficiency and therefore range. The general consensus here is that if its below 10C outside, its maybe worthwhile doing for longer trips. If you're hopping around the city, maybe not.

For charging however, if you are heading to a charger and its below 10C, it seems that enabling the preheat (as shown above) will also improve efficiency charging, and in some cases - allow charging altogether. Before the video above, I wasn't aware that extreme temperature could prevent charging entirely.

 

[Sloucher]

It has been advised by some owners on here that if it's a cold day and you're on your way to get the car charged, switch the pre-heat on a good while before attempting the charge. I'm afraid I don't remember just how long before though.

 

[ukflyer]

I seem to recall reading that pre-heating the battery, prior to charging, is only beneficial when DC fast charging. When AC charging at 7kw, it is not required. Can anyone confirm this? I certainly haven’t noticed a deterioration of charging speed at home, and can rule of thumb that it will charge 10% per hour.

 

[liberostelios]

Preconditioning the battery on a cold night won't only improve your efficiency, when you drive, and your charging speed, but will also help retain the battery's health. Batteries do not like it when they operate in too cold (or too hot) temperatures, so if you precondition them before a long journey it would help them degrade slower, in the long term.

 

[Pebble]

I seem to recall reading that pre-heating the battery, prior to charging, is only beneficial when DC fast charging. When AC charging at 7kw, it is not required. Can anyone confirm this? I certainly haven’t noticed a deterioration of charging speed at home, and can rule of thumb that it will charge 10% per hour.

Yes, James Coates of James & Kate on Youtube, He does 1000's of miles a year and from experience reckons battery heating is not effective on sub 50kw chargers.

 

[Ayoull]

Preconditioning the battery on a cold night won't only improve your efficiency, when you drive, and your charging speed, but will also help retain the battery's health. Batteries do not like it when they operate in too cold (or too hot) temperatures, so if you precondition them before a long journey it would help them degrade slower, in the long term.

NMC and LFP only suffer cold degredation at temperatures below -10C preheating doesn't improve battery health unless below these temperatures, the preheating is only really beneficial for rapid charging inorder to improve the batteries ability to accept a significant amount of charge in a short period of time.

By actually driving the car the battery will heat up to 20-25C in around 15 minutes due to heat generated by the chemicals reactions being exothermic within a battery, where as preheating using the 7kW battery heater will take almost half an hour, if the car is stationary, to reach the same temperature.

 

[jebimasta]

NMC and LFP only suffer cold degredation at temperatures below -10C preheating doesn't improve battery health unless below these temperatures, the preheating is only really beneficial for rapid charging inorder to improve the batteries ability to accept a significant amount of charge in a short period of time.

By actually driving the car the battery will heat up to 20-25C in around 15 minutes due to heat generated by the chemicals reactions being exothermic within a battery, where as preheating using the 7kW battery heater will take almost half an hour, if the car is stationary, to reach the same temperature.

Interesting! that's faster heating up than I'd thought
I recently did a 180 mile round trip through mid wales, on the way up I had charged the car and scheduled preheating, and got 3.8m/kWh. On the return journey I had charged the day before so no preheat, drove the "same", with the same load, same settings, and only managed 3.3m/kWh.

I had assumed this was because I didn't preheat, but it's a 2.5 hour drive so battery should be plenty warm enough.

I guess the geography of the drive must have made a big impact.

 

[Ayoull]

Interesting! that's faster heating up than I'd thought
I recently did a 180 mile round trip through mid wales, on the way up I had charged the car and scheduled preheating, and got 3.8m/kWh. On the return journey I had charged the day before so no preheat, drove the "same", with the same load, same settings, and only managed 3.3m/kWh.

I had assumed this was because I didn't preheat, but it's a 2.5 hour drive so battery should be plenty warm enough.

I guess the geography of the drive must have made a big impact.

I'm referring to battery preheating not the cabin preheating, which will benefit range as the cabs already warm so the PTC heater is only maintaining temp opposed to trying to heat the cab up.

 

[jebimasta]

I'm referring to battery preheating not the cabin preheating, which will benefit range as the cabs already warm so the PTC heater is only maintaining temp opposed to trying to heat the cab up.

Yep, so am I, I should have been explicit

 

[spence7788]

How times change.......was only a couple of years ago with my leaf 40 with no liquid cooling when I constantly had to baby it to keep the battery temps down on big milage days

Tbh in the UK unless it's very cold and a long journey is ahead where you need every bit of range (efficiency) it's just a waste of energy pre heating prior to leaving home imo.

It's not very often I use rapid chargers these days but the couple of times I've tested the 4 on Tesla superchargers it's got well over 120kwh without trying, admittedly this is after a few miles.

 

[hharzel]

NMC and LFP only suffer cold degredation at temperatures below -10C preheating doesn't improve battery health unless below these temperatures, the preheating is only really beneficial for rapid charging inorder to improve the batteries ability to accept a significant amount of charge in a short period of time.

By actually driving the car the battery will heat up to 20-25C in around 15 minutes due to heat generated by the chemicals reactions being exothermic within a battery, where as preheating using the 7kW battery heater will take almost half an hour, if the car is stationary, to reach the same temperature.

I'd really love to see actual data on how cold weather and battery preheating affects the battery life, but it seems there is none available - just guesses and assumptions. While it is obvious that warming the battery is beneficial, the big question that is still unaswered to me is: if you use battery heating all the time when it's 0 degrees celsius cold or below before driving the car, does it maximize battery life or does it actually cause just more wear?

My car will likely be exposed to cold weather during its entire life in winter and I can only preheat from the HV battery. Using preheating all the time I get only about 130km (80mls) of range so I have to charge more often, causing more wear. Not preheating I get pretty average consumption overall but I find it concerning that I'm still getting regeneration values in the range of 10-15 when slowing down (at -15C). Is it certain that the regenerating energy goes into heating and not into the battery? The decision between performance and battery health is always a compromise, so which one did MG decide to opt for? Nobody knows