Battery Degradation Scientifically Explained

[Leafdriver333]

Thank you for the thorough explanations, I have never owned a $10,000 battery before, so I have made it my business to understand the best practices for caring for it. I think your videos should be required "reading" for any EV owner, and I am somewhat surprised Tesla doesn't do a better job of educating their customer.

Born in 1955 I've owned my share of motor vehicles, and nothing comes close to this LR AWD M3.
Have you taken delivery of your M3 yet?

I have dealt with a lot of radio control cars and rechargeable batteries from NiCd to NiMH to LiPo. And also brushless motors.
EV is so much like a RC car in acceleration, sound, and feel. I love it.

 

[Tron 3]

I have dealt with a lot of radio control cars and rechargeable batteries from NiCd to NiMH to LiPo. And also brushless motors.
EV is so much like a RC car in acceleration, sound, and feel. I love it.

Nothing like it. I'll wager you never saw yourself riding in anything that like that...

 

[evM3Sekar]

There are some very thoughtful and interesting questions in this thread!

1. For TMF to be a concern for a typical electrode, the temperature window needs to be over a much higher window than we would normally operate or store a Li-Ion cell, (because of the limited thermal stability window of the electrolyte). The volume expansion of the electrolyte at low temperature theoretically could result in TMF of an electrode, however some work out of Jeff Dahn's group shows that doing this a limited number of times should not have much of an effect.

Link to paper (Open Access) - Differential Thermal Analysis of Li-Ion Cells as an Effective Probe of Liquid Electrolyte Evolution during Aging

It's interesting that the small thermal stability window essentially avoids the traditional TMF issues - one less variable to worry about in this complex process. Thanks for pointing out the paper - quickly perused through it, and I see what you mean.

Talking of EV batteries, that's the only research I had done about M3, before pulling the trigger. I discovered all other cool things in the car only after I got the car. I hope you get your M3 soon!

 

[Aelione]

@EV-Tech Exp : What is better for longevity over 5 years of use--(A) charging from 70% to 80% daily or (B) charing from 30% to 80% once a week?

Or is it negligible? And, is this true of iPhones too? is it better to let them charge in the range of 30-80% vs. up to 100%?

 

[Kenz]

Sean Mitchell made a good video describing his abuse of his battery and its failure due to the abuse.

 

[Kenz]

Charge at home or work on a level 2 charger most of the time and try to keep the charge level between 20 - 80% for most days.

 

[jdw]

@EV-Tech Exp : What is better for longevity over 5 years of use--(A) charging from 70% to 80% daily or (B) charing from 30% to 80% once a week?

Or is it negligible? And, is this true of iPhones too? is it better to let them charge in the range of 30-80% vs. up to 100%?

Many shallow charge cycles are better for lithium batteries than fewer deep ones and less time spent at 100% is better, especially in high heat environments. Apple's phoneOS 13 will reportedly stop at 80% overnight and top off to 100% in the morning.

 

[SSonnentag]

In a car with battery thermal management, how can battery temperature realistically affect longevity? The car prevents the batteries from getting too hot, thus avoiding damage, even by frequent use of DC fast charging. This is fairly well proven by the fact that Tesloop cars, which are only and always supercharged, don't suffer excessive battery degradation.

 

[Dr. J]

In a car with battery thermal management, how can battery temperature realistically affect longevity? The car prevents the batteries from getting too hot, thus avoiding damage, even by frequent use of DC fast charging. This is fairly well proven by the fact that Tesloop cars, which are only and always supercharged, don't suffer excessive battery degradation.

But:
"...the most notable major events over the vehicle’s life time were the front drive unit replacement at 36,404 miles due to a part failure and two main battery replacements, one at 194,237 miles, the other at 324,044 miles. All three replacements were covered under the car’s 8-year, unlimited-mile warranty.

The first battery pack the Tesla Model S had experienced 1.2 miles of range lost per 10,000 miles while being driven about 17,000 miles per month and was replaced due to a battery chemistry issue. The second pack was losing about 4.7 miles every 10,000 miles driven, and its replacement was due to a defect in the battery assembly. The current battery is a 90 kWh pack and showing a loss of about 2.4 miles of range per 10,000 miles driven; however, about midway through the mileage, the car was transitioned from a long distance shuttle to a daily rental car, so the averages may not be a great reflection on its efficiency. At about 126,000 miles into the new pack, eHawk’s battery degradation is around 9%."

Tales from a Tesla Model S with 450,000 miles: Battery life, durability, and more

 

[jdw]

In a car with battery thermal management, how can battery temperature realistically affect longevity? The car prevents the batteries from getting too hot, thus avoiding damage, even by frequent use of DC fast charging. This is fairly well proven by the fact that Tesloop cars, which are only and always supercharged, don't suffer excessive battery degradation.

1-Charge to 100% and park in the sun on hot asphalt in Texas for a week.
2-Drive at 80MPH for a few hours on a hot day, punching it every now and then and roll into a SuperCharger with a low state of charge and charge to 100%

The battery cooler comes on when the battery is at 40C and the car is on. 40C is also the temp at which battery damage from high SOC and high charge rates begins.

Degradation is not a binary event, but cumulative damage over time. You can't avoid every event that is not good for a battery, but it makes good sense to avoid the ones you can.

The Tesloop car is also on its third battery ....

 

[dhrivnak]

In a car with battery thermal management, how can battery temperature realistically affect longevity? The car prevents the batteries from getting too hot, thus avoiding damage, even by frequent use of DC fast charging. This is fairly well proven by the fact that Tesloop cars, which are only and always supercharged, don't suffer excessive battery degradation.

I believe he was talking about lithium batteries in general. Some cars like the LEAF do not have liquid cooling and they did have issues in hot climates.

 

[Leafdriver333]

1-Charge to 100% and park in the sun on hot asphalt in Texas for a week.
2-Drive at 80MPH for a few hours on a hot day, punching it every now and then and roll into a SuperCharger with a low state of charge and charge to 100%

The battery cooler comes on when the battery is at 40C and the car is on. 40C is also the temp at which battery damage from high SOC and high charge rates begins.

Degradation is not a binary event, but cumulative damage over time. You can't avoid every event that is not good for a battery, but it makes good sense to avoid the ones you can.

The Tesloop car is also on its third battery ....

Considering Body temp is 37°C, damaging effect happening at 40°C doesn't seem too advanced for today's technology.

 

[darth_vad3r]

Considering Body temp is 37°C, damaging effect happening at 40°C doesn't seem too advanced for today's technology.

It’s like getting a fever ... I feel damaging effects way before 40°C (104°F)

 

[Dr. J]

It’s like getting a fever ... I feel damaging effects way before 40°C (104°F)

Maybe wear a different hat?

 

[darth_vad3r]

Maybe wear a different hat?

NOOOOOooooooooo......

 

[MrABRanch]

Hey could you give any advice for owners who can only charge at SC (I live in a condo with no access to charging) - I charge every 5 days or so to 90% (so far in not very hot weather in PA) and it goes down to 10-15% but only for the last leg of the drive to the SC (it's generally around 20% sitting the last night before the SC drive) - I'm gonna aim to charge more in the 15-25% range and only to 80% as it gets hotter, which will mean I need to charge more often, probably every 3-4 days...Any thoughts/advice on this routine?

 

[SilverGS]

I'm glad you found my video helpful, and it is nice to see it posted here given the knowledgeable crowd on this forum.

Feel free to ask me any specific questions on this topic if not addressed by the video.

Thanks for the great educational video!

Got a couple of questions for you -

1. What rate is considered "Fast charge"? I don't have a Tesla yet, but can't stop consuming as much information as I can get my hands on. A friend of mine who just got an M3 ran a cable from his stove and is getting 52Km/hour as his charge rate - this would be from a Nema 14-50 plug (see attached screen shot)
2. How long does it take typically to pre-condition a battery (and what ambient temperature would that be)?

 

[Zoomit]

I'll take a stab at these:

Any thoughts/advice on this routine?

Looks like a reasonable plan, given your circumstances. I'm not sure it matters starting at 25% vs 10% though. Just don't store the battery at very low SoC.

• What rate is considered "Fast charge"? I don't have a Tesla yet, but can't stop consuming as much information as I can get my hands on. A friend of mine who just got an M3 ran a cable from his stove and is getting 52Km/hour as his charge rate - this would be from a Nema 14-50 plug (see attached screen shot)

• How long does it take typically to pre-condition a battery (and what ambient temperature would that be)?

Fast charge is typically used as short-hand for DC Fast Charging which is when the charger is outside the vehicle and provides DC power directly to the battery. It ranges from ~20kW to 350kW. Anything coming from single-phase AC power is not fast charging is very benign for the battery.

If you're referring to On-Route Battery Warmup, that seems to take at least 15 minutes but it of course depends on the starting temperature and how hard the car is being driven. ORBW targets 40C according to multiple sources at Tesla.

 

[SilverGS]

I'll take a stab at these:

Looks like a reasonable plan, given your circumstances. I'm not sure it matters starting at 25% vs 10% though. Just don't store the battery at very low SoC.

Fast charge is typically used as short-hand for DC Fast Charging which is when the charger is outside the vehicle and provides DC power directly to the battery. It ranges from ~20kW to 350kW. Anything coming from single-phase AC power is not fast charging is very benign for the battery.

If you're referring to On-Route Battery Warmup, that seems to take at least 15 minutes but it of course depends on the starting temperature and how hard the car is being driven. ORBW targets 40C according to multiple sources at Tesla.

Thanks! For the second question I just assumed the battery could be pre-conditioned at home before you leave the house while its still plugged in.

 

[Zoomit]

Thanks! For the second question I just assumed the battery could be pre-conditioned at home before you leave the house while its still plugged in.

If the battery is very cold (showing snowflake on screen) and the cabin pre-heat is turned on, the car will also warm the battery to increase efficiency and allow for flexible power output/regen. I don't know what battery temperature triggers that but I'd guess 0 to -10C, possibly lower.