7th May 2024
Written by Mitchell LakinAC vs DC: Effects on Battery Health
With rapid and ultra-rapid charging now bringing speeds beyond ten times faster than their counterparts. With quicker, more efficient charging, it is only natural for EV owners to worry whether such a benefit comes with any costs – in this case, the degradation of battery life. Our article breaks down the latest research to provide an answer to this growing question, and what else – if anything – eats into the health of your new EV.
AC and DC – What Is the Difference?
You probably know that AC – or alternating current – charging is a slower method compared to their quicker DC – or direct current – equivalents. Before understanding whether this influences the degradation of your battery, it’s important to know why one is faster than the other.
DC is the charging type that offers up rapid and ultra-rapid speeds with rates now charging 80% in under 30 minutes. Although AC and DC can both be used to power a vehicle, its battery will only ever store DC. As a result, DC chargers have a built-in converter to switch the current type from AC, at the grid’s end, to DC before it enters the vehicle. AC chargers, on the other hand, leave the current as it is so that the conversion must take place within the car.
With that in mind, do these two types of charging points have a different effect on battery health over time?
State of Health
Battery health degradation is an area that has little data, especially following real-world performance of EVs over a set period. This is largely due to the amount time EVs have populated our roads, so we can expect this data to start to blossom in the coming years. For example, in January 2024, Geotab published their in-depth comparison of 6,300 electric vehicles with a variety of makes and models, accounting for 1.8 million days of data, all with a goal of learning more about battery health.
First of all, why does a battery’s health decline and what does it mean?
EV batteries typically have a higher power capacity than the powertrain can manage, leading to the natural degradation of the battery over time. This degradation permanently diminishes the battery’s energy storage or power output capabilities. Much like batteries you will find in a mobile phone, you will get less use – in this case, range – out of a full charge.
This study clarified several factors that affect battery health, with the type of charge being one of them. In short, it concludes that all the motor brands in their study had an average battery efficiency decline of 2.3% per year. Meaning, if you purchase an EV with a 150-mile range, you’ll only lose 17 miles after 5 years. This is a highly promising figure as any driver would tell you that, at this rate, the other components of a vehicle – electric or otherwise – will deteriorate faster.
How Much Does Charging Type Actually Affect the Battery?
Geotab’s study compiled the following graph which took data from three sets of EVs with varying degrees of DC charge usage, with the alternate charging being AC. However, it is worth noting that each of the three categories of vehicles were being tested in a hot climate, a factor which is known to increase battery degradation In fact, one of the primary reasons why DC charging is known to affect battery health more is due to the high currents resulting in higher battery temperatures. With that in mind, the state of health difference between the group of vehicles that have never used DC compared to those that use it on the most regular basis is less than 0.1%. As for the UK, its cooler climate means degradation rates are likely to be even smaller.
In short, the type of charging does affect a batteries state of health but the rate of which is so minor it would probably go unnoticed, especially when compared with other degradation factors.
What Else Affects Battery Health?
Temperatures:
As stated above, a vehicle exposed to higher temperatures on a regular basis will experience a higher rate of degradation. If you live in Arizona, not much can be done to drive your EV in cooler temperatures. However, the degradation occurs both when the vehicle is in use and parked up, so if there is a cooler alternative for your parking arrangements, it might be worth considering.
Vehicle age:
Battery decline is unfortunately not consistent throughout its lifespan, a finding that’s commented on by a number of sources such as RAC. As a battery pushes closer to ten years of life, the state of health begins to drop off or “heel”. This is why an EV battery’s second life is not often used to power another vehicle but rather less intensive purposes.
The Charging Buffer
One of the greatest impacts on battery health is how often you keep your vehicle above 80% and below 20%. Reaching and keeping your EV at near empty or full capacity has significant ramifications on battery health. Keeping your EV between 20-80% so that it is within the charging buffer will have a noticeable effect on battery health and range over its lifespan.
To keep updated on more advise like this and our latest news regarding installations and projects, follow us on:
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Linkedin: car-charged-uk
AC vs DC: Effects on Battery Health
With rapid and ultra-rapid charging now bringing speeds beyond ten times faster than their counterparts. With quicker, more efficient charging, it is only natural for EV owners to worry whether such a benefit comes with any costs – in this case, the degradation of battery life. Our article breaks down the latest research to provide an answer to this growing question, and what else – if anything – eats into the health of your new EV.
AC and DC – What Is the Difference?
You probably know that AC – or alternating current – charging is a slower method compared to their quicker DC – or direct current – equivalents. Before understanding whether this influences the degradation of your battery, it’s important to know why one is faster than the other.
DC is the charging type that offers up rapid and ultra-rapid speeds with rates now charging 80% in under 30 minutes. Although AC and DC can both be used to power a vehicle, its battery will only ever store DC. As a result, DC chargers have a built-in converter to switch the current type from AC, at the grid’s end, to DC before it enters the vehicle. AC chargers, on the other hand, leave the current as it is so that the conversion must take place within the car.
With that in mind, do these two types of charging points have a different effect on battery health over time?
State of Health
Battery health degradation is an area that has little data, especially following real-world performance of EVs over a set period. This is largely due to the amount time EVs have populated our roads, so we can expect this data to start to blossom in the coming years. For example, in January 2024, Geotab published their in-depth comparison of 6,300 electric vehicles with a variety of makes and models, accounting for 1.8 million days of data, all with a goal of learning more about battery health.
First of all, why does a battery’s health decline and what does it mean?
EV batteries typically have a higher power capacity than the powertrain can manage, leading to the natural degradation of the battery over time. This degradation permanently diminishes the battery’s energy storage or power output capabilities. Much like batteries you will find in a mobile phone, you will get less use – in this case, range – out of a full charge.
This study clarified several factors that affect battery health, with the type of charge being one of them. In short, it concludes that all the motor brands in their study had an average battery efficiency decline of 2.3% per year. Meaning, if you purchase an EV with a 150-mile range, you’ll only lose 17 miles after 5 years. This is a highly promising figure as any driver would tell you that, at this rate, the other components of a vehicle – electric or otherwise – will deteriorate faster.
How Much Does Charging Type Actually Affect the Battery?
Geotab’s study compiled the following graph which took data from three sets of EVs with varying degrees of DC charge usage, with the alternate charging being AC. However, it is worth noting that each of the three categories of vehicles were being tested in a hot climate, a factor which is known to increase battery degradation In fact, one of the primary reasons why DC charging is known to affect battery health more is due to the high currents resulting in higher battery temperatures. With that in mind, the state of health difference between the group of vehicles that have never used DC compared to those that use it on the most regular basis is less than 0.1%. As for the UK, its cooler climate means degradation rates are likely to be even smaller.
In short, the type of charging does affect a batteries state of health but the rate of which is so minor it would probably go unnoticed, especially when compared with other degradation factors.
What Else Affects Battery Health?
Temperatures:
As stated above, a vehicle exposed to higher temperatures on a regular basis will experience a higher rate of degradation. If you live in Arizona, not much can be done to drive your EV in cooler temperatures. However, the degradation occurs both when the vehicle is in use and parked up, so if there is a cooler alternative for your parking arrangements, it might be worth considering.
Vehicle age:
Battery decline is unfortunately not consistent throughout its lifespan, a finding that’s commented on by a number of sources such as RAC. As a battery pushes closer to ten years of life, the state of health begins to drop off or “heel”. This is why an EV battery’s second life is not often used to power another vehicle but rather less intensive purposes.
The Charging Buffer
One of the greatest impacts on battery health is how often you keep your vehicle above 80% and below 20%. Reaching and keeping your EV at near empty or full capacity has significant ramifications on battery health. Keeping your EV between 20-80% so that it is within the charging buffer will have a noticeable effect on battery health and range over its lifespan.
To keep updated on more advise like this and our latest news regarding installations and projects, follow us on:
Facebook: Car Charged UK
Instagram: Car_Chargeduk
Twitter: CarChargedUK
Linkedin: car-charged-uk