Is Fast Charging Bad For Battery Life? -- Engineering Explained Answers the Question

Here's a text summary (by ChatGPT)

• Fast Charging Accelerates Battery Degradation
  Studies show that higher charging rates lead to faster battery wear, with faster degradation occurring when using fast charging frequently.
• Why Faster Charging Degrades Batteries
  Fast charging throws lithium ions into the battery faster than they can properly diffuse within the graphite particles, causing lithium plating and eventual damage.
• Factors Influencing Degradation
  Three main factors affect degradation: state of charge, charge rate, and battery temperature. At high states of charge, the lithium ions have fewer available spaces, increasing the risk of lithium plating.
• Temperature’s Role
  Warmer batteries reduce the risk of lithium plating, but temperatures that are too high can increase SEI layer formation, causing long-term capacity loss.
• Practical Solutions
  Electric vehicles automatically adjust charging rates and temperatures to minimize the effects of fast charging. While fast charging has some impact, modern batteries and vehicle systems mitigate most negative effects.

Insights Based on Numbers

• 5% degradation difference: A study found that after 50,000 miles, a car charged exclusively with fast chargers retained 70% of its original capacity compared to 75% for slow-charged cars.
• Temperature effect on degradation: A warmer battery charged at around 25°C could achieve over 3,000 full cycles before significant capacity loss occurred, compared to cold batteries, which suffer more from lithium plating.

• 5% degradation difference: A study found that after 50,000 miles, a car charged exclusively with fast chargers retained 70% of its original capacity compared to 75% for slow-charged cars.

70-75% after 50k miles seems to go against real world degradation seen in EVs with a long history of milage.

But also even taking those at face value a 5/30 = is a 17% increase by using a fast charger.. which seems like a very small difference.

TLDR; supercharging infrequently or even somewhat frequently doesn't harm your battery in any way you're likely to notice during ownership.

Use 80% as max charge regularly and 100% when needed and you'll be fine. Everything else isn't worth worrying about.

JayGT4 said:

Here's a text summary (by ChatGPT)

• Fast Charging Accelerates Battery Degradation
  Studies show that higher charging rates lead to faster battery wear, with faster degradation occurring when using fast charging frequently.
• Why Faster Charging Degrades Batteries
  Fast charging throws lithium ions into the battery faster than they can properly diffuse within the graphite particles, causing lithium plating and eventual damage.
• Factors Influencing Degradation
  Three main factors affect degradation: state of charge, charge rate, and battery temperature. At high states of charge, the lithium ions have fewer available spaces, increasing the risk of lithium plating.
• Temperature’s Role
  Warmer batteries reduce the risk of lithium plating, but temperatures that are too high can increase SEI layer formation, causing long-term capacity loss.
• Practical Solutions
  Electric vehicles automatically adjust charging rates and temperatures to minimize the effects of fast charging. While fast charging has some impact, modern batteries and vehicle systems mitigate most negative effects.

Insights Based on Numbers

• 5% degradation difference: A study found that after 50,000 miles, a car charged exclusively with fast chargers retained 70% of its original capacity compared to 75% for slow-charged cars.
• Temperature effect on degradation: A warmer battery charged at around 25°C could achieve over 3,000 full cycles before significant capacity loss occurred, compared to cold batteries, which suffer more from lithium plating.

Click to expand...

Recently, a study was released showing no evidence that fast chargers accelerate battery degradation. I plan to use a fast charger for trips under 300 miles; for anything longer, I'll stick with my ICE vehicle due to my limited patience.

The Porsche High Volt Battery has a cover for 'Excessive Loss of Capacity,' but I'm not worried about that. I intend to keep my Macan 4 for the long term. With proper care, the battery can last over 200,000 miles."


Basic Recommendations:

• Keep the maximum charge between 10% and 60% for short commutes.
• For long commutes, maintain the maximum charge between 10% and 80%.
• If you're planning to travel, charge to 100% right before your trip. Aim to charge 80% during your travels—it's more efficient than waiting to reach 100%, increasing the battery's longevity.

The lifecycle of the Macan EV battery is approximately 462,000 miles for the 100 kWh model.


Porsche High-Voltage Battery Coverage

The Porsche Battery Electric Vehicle high-voltage battery is covered against defects in materials or workmanship for a period of 8 years/100,000 miles and against excessive loss of capacity, as defined below.

Excessive Loss of Capacity If a capacity measurement performed at a authorized Center shows, at the times specified below, that net battery capacity is less than the percentages specified below (the “Warranted Value”), any percentage that falls below the relevant Warranted Value constitutes “excessive loss of capacity”

• 100% of net battery capacity on the date the car is first delivered to the first retail purchaser or the date it is first used as a demonstrator, lease, or company car, whichever comes first.

• 80% of net battery capacity within the first 3 years/37,500 miles, whichever occurs first.

70% of net battery capacity within the first 8 years/100,000 miles, whichever occurs first.

Update: Scientists Reveal how EV Fast Charging Impacts Battery Health

EV Study Reveals Impacts of Fast Charging (recurrentauto.com)

• Scientists expect high voltage charging (DC fast charging) to accelerate battery degradation, but ongoing observations from 2012 to 2023 Teslas do not show any evidence.
• Accelerated range loss or battery degradation may still happen later in an EV’s life.
• This study looks at real-world driving data from 13,000 Tesla vehicles. Due to EV adoption trends in the US, most vehicles are newer than 2018.

A study found that after 50,000 miles, a car charged exclusively with fast chargers retained 70% of its original capacity compared to 75% for slow-charged cars

Click to expand...

Lots of important detail lost here by the robot summary. This involved a 2012 Nissan Leaf in Phoenix, Arizona. Possibly the worst possible case for thermal management. I don't think anyone else sells a car today without active thermal management of the battery, for exactly this reason.

I think this is well out of date.
I had an interesting discussion with my SA this week. They know that Porsche recommend 80% but they always charge their demonstrators and loan Taycans to 100% as they don’t know when it will be needed and have seen no degradation over 3 years.
Similarly I haven’t seen any on my Polestar over same period. Always charging to 90% and 100% when needed.

I had a 5% loss on my Tesla M3 LR after 3 years and 100000 km (measured by Tesla-Fi). Never cared too much if I needed a fast charge but generally I charged more than 90% of times at home with 7.4kW.

I’m no expert, but if the car can regenerate up to 240kW when braking you are technically fast charging every time you brake.

rpbrazil said:

I’m no expert, but if the car can regenerate up to 240kW when braking you are technically fast charging every time you brake.

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but the duration is sooooooo much shorter and typically the SOC is not close to "full"…so yeah you're fast charing but for like less than 30 seconds a whack at the brakes…and it tapers pretty quickly (vehicle doesn't go fast enough to generate a full 240 kW for very long under braking)

The good news is that Macan seems like has a unique and smart feature: it will automatically discharge the battery if it's charged to high SOC levels and the outside temperature is high. This helps reduce battery degradation. Here are more details:

PanameraFrank said:

Use 80% as max charge regularly and 100% when needed and you'll be fine. Everything else isn't worth worrying about.

Click to expand...

Yup. The Macan EV manual (in the My Porsche app) also recommends keeping the battery between 25% and 50% if idle for long periods of time (2 weeks or more). Not sure it's going to have a visible impact during my ownership of the car, but it's the most optimal way to preserve the battery, it seems.

the more you know...

these cars have NMC batteries...but it's still an interesting watch as he talks about the differences still