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Discussion Starter · #1 ·
Courtesy of MYEV.com

A lot of folks, myself included, are curious about the effects of different charging rates. I thought I'd pass this along.

Effects Of Frequent Fast Charging

An electric car’s ability to accept higher charge currents is affected by the battery chemistry. The accepted wisdom in the industry is that faster charging will increase the rate at which an EV’s battery capacity will decline. However, a study conducted by the Idaho National Laboratory (INL) concluded that while an electric car’s battery will deteriorate faster if it’s only power source is Level 3 charging (which is almost never the case) the difference isn’t particularly pronounced.

The INL tested two pairs of Nissan Leaf EVs from the 2012 model year that were driven and charged twice daily. Two were replenished from 240-volt "Level 2" chargers like those used in one's garage, with the other two taken to Level 3 stations. They were each were driven on public reads in the Phoenix, Ariz. area over the course of a year. They were tested under the same conditions, with their climate control systems set at 72 degrees and the same set of drivers piloting all four cars. The vehicles’ battery capacity was tested at 10,000-mile intervals.

After all four test cars had been driven for 50,000 miles, the Level 2 cars had lost around 23 percent of their original battery capacity, while the Level 3 cars were down by around 27 percent. The 2012 Leaf had an average range of 73 miles, which means these numbers represent a difference of around just three miles on a charge.

It should be noted that much of the INL’s testing over the 12-month period was conducted in extremely hot Phoenix weather, which can inherently take its own toll on battery life, as would the deep charging and discharging necessary to keep the relatively short-range 2012 Leaf running.

The takeaway here is that while DC charging may have an effect on an electric car’s battery life, it should be minimal, especially in that it’s not a primary charging source.
 

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I stopped reading when I saw the word "Leaf". Leaf did not have active thermal management so the findings here in no way apply to any modern EV.
Assuming what you say is correct, the study still may hold some merit as it would represent a "worst case scenario" and the BMW's superior design should be even less effected.
 

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Assuming what you say is correct, the study still may hold some merit as it would represent a "worst case scenario" and the BMW's superior design should be even less effected.
Nissan Leaf of 2012 is almost 2 generation earlier then the BMW iX. Battery Management is key for electrical cars and as only Tesla and BMW has a long history in testing electrical vehicles (remember i3 with his different battery sets, and the i8), they have developed the knowledge to make good battery management. Some people are saying that BMW cars are not really fast charging vehicles. Remember some electrical laws: heat creation is by current squared. The resistance of the Li-ion battery is increasing by the charge%. So charging at high speed (inclusive cooling of the battery pack) when charging state is low, will not decrease the capacity of your battery as long as you don't charge until 100%.
I drove now 27600 km (17150 miles) and don't see any decrease in capacity until now but I rarely charge until 100% in AC and max up to 65% in DC (fastest if you have to drive long distances.
 

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What's interesting here is that Leaf had a horrific BMS/thermal management system and yet L3 only deteriorated the battery 4% more over 50k miles than L2 charging did.

Really seems like L3 is not to be feared in modern EVs.
This checks out with my personal experience of 4 years with a Tesla Model 3 - 2 years I was only using L3 charging, and often to 90%, maybe 5-10x/year all the way to 100%. The car was parked outdoors year round in NYC so down to 20F and up to 100F. Despite that it only lost ~9% of battery over 4 years and 25k miles.

A properly garaged EV, with a higher mix of L2 charging, and charging generally to 80% should see even better battery retention.

I also think BMW keeps more of the pack "in reserve" vs Tesla, so apparent usable range likely won't drop as fast.
 

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Oh well, with the 2 years free EA charging here, I exclusively charge at L3 chargers primarily, for free, unless I'm at a hotel with free L2 chargers Pretty much 95% L3 charging last 5 months, over 300 charges and 8300kWh on L3, 16k miles. I don't really care if it deteriorates that quickly honestly, I'm pretty used to the crappy 200-230 range on the 50.
 

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Oh well, with the 2 years free EA charging here, I exclusively charge at L3 chargers primarily, for free, unless I'm at a hotel with free L2 chargers Pretty much 95% L3 charging last 5 months, over 300 charges and 8300kWh on L3, 16k miles. I don't really care if it deteriorates that quickly honestly, I'm pretty used to the crappy 200-230 range on the 50.
Have you noticed range drop off? I guess with season changes you probably wouldn't.
 
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