Does Fast Charging Ruin Your Electric Car's Battery? -- Engineering Explained

[flapjake314]

I’ve lost 12% on my battery…. I fast charged the first month I had it once a week as I just had level 1 charging at that time. I’ve fast charged maybe 15 times and that is likely on the higher side. I charge on a level 2 at home to 80% otherwise. I was actually kind of surprised, I was not expecting that big of a hit. I had attributed the loss to worn and then the new aftermarket tires I had installed. lol

how do you know that you lost 12% on your battery?

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[flapjake314]

I'm afraid I have to disagree that it's misleading. Fast charging can be an issue, and there are posts within this thread that support what the EE video explains. It's probably a non-issue for most people, but it's a data point to consider if you want to keep your MME's battery, or even your iPhone's, running optimally for as long as possible.

to state something factually true but would lead most people to have the incorrect conclusion is the specific definition of misleading, no?

 

[flapjake314]

I think the important metric is full charge cycles. The data he presented shows the battery will drop to 80% SOH after approximately 1,200 full charge cycles. Use conservatively 200 miles per charge cycle, that's around 240,000 miles. Most people don't keep their cars for 240,000 miles.

It's a non issue.

this useful contextualization

i have also heard (and see in my poll) that the cycles matter less than the age of the battery, i.e. even if you very few miles/cycles on a 2 year old battery is going to have x% degradation which is itself similar to a 2 year old batter with many more cycles

that said based on tesla data the age degradation levels off and the battery holds 75-85% for a very long time, e.g. > 10 years at which point most people plan to change cars anyway (and the batteries get recycled)

 

[medriver]

The things that'll kill your NMC battery are leaving it at extremes of charge for a prolonged period of time and heat death, the remainder is up to you.

 

[Kabish]

how do you know that you lost 12% on your battery?

OBD Scanner and I guess I lied 11.5% but close enough!! I also, in the past year, changed to 85% SoC. I read someplace on here that 80% was not letting the car get updates. I changed to 85% and got like 4 updates pretty quickly. Could had been a coincidence could had been the 85%.

 

[lwilliams0514]

i have a post to track SOH where i specifically ask about DCFC usage

strongly seems like minimal impact to the battery frankly... but i am not an engineer and it's a small dataset

Agreed. I just added my SOH to @flapjake314's data and there seems to be more of a correlation to age of the battery instead of whether you fast charge or not.

 

[flapjake314]

OBD Scanner and I guess I lied 11.5% but close enough!! I also, in the past year, changed to 85% SoC. I read someplace on here that 80% was not letting the car get updates. I changed to 85% and got like 4 updates pretty quickly. Could had been a coincidence could had been the 85%.

out of the nearly 100 datapoints i have collected thus far, only 1 person was lower than your SOH. that person was at 87% with 64k miles on the odometer. how many miles do you have and what's the build date of your car?

i'll note lwilliams is at 123k miles and still at 93.5% SOH

if your SOH is truly correct (some people say you need to do a deep charge every month to get an accurate %) you are one of the lowest SOH around. if you think there are any habits or reasons that contributed to that let me know and i'll keep an eye on it from other users in my dataset.

and feel free to enter your data point into my post to track yourself going forward and compare against others.

 

[Kabish]

out of the nearly 100 datapoints i have collected thus far, only 1 person was lower than your SOH. that person was at 87% with 64k miles on the odometer. how many miles do you have and what's the build date of your car?

i'll note lwilliams is at 123k miles and still at 93.5% SOH

if your SOH is truly correct (some people say you need to do a deep charge every month to get an accurate %) you are one of the lowest SOH around. if you think there are any habits or reasons that contributed to that let me know and i'll keep an eye on it from other users in my dataset.

and feel free to enter your data point into my post to track yourself going forward and compare against others.

Miles: 71,704
Date: 6/21
Original Owner, purchased in July 21 if I remember correctly

So tonight I was playing around with ABRP and got to see that 11.5% change to 12%..... I did fully charge my car last weekend as I had to drive a lot that day for the dogs grooming and I too wondered if a full charge would be needed to get a true SOH. I used to charge to 100% every two or three months, but then I read that it really did not matter so I stopped doing it.

As far as charging, I fast charged the first month or so that I owned it maybe once a week. Then I got my L2 installed and no longer had the need for it. I would say I've not DCFC more than a dozen times or so.

As far as habits... Really none... I drive a lot of local miles however. On 6/28/24 I had my tires changed out, I was at 63,000 something miles at that time, so around 2,500 miles driven per month. My insurance quotes me out, with "verified milage" as driving 31,000-40,000 a year, which I think its a bit over estimated. About 2.5yrs ago we moved up to a city called Alpine, CA which increased my commutes for work/kids.

I live in San Diego, so average weather. I park in a garage that is not claimant controlled so it gets warm/cold. I use a Wallbox charger and charge to 85% from about 57ish% almost every week day. There are a hand full of times I'll forget to plug in and I"ll charge from 30% to 85%, but that does not happen often. My car has never seen a 100% charge and sit longer than the evening it charged, its also never been completely discharged, think the lowest ever was 5% with me typically not going below 20%. I don't drive aggressively, got about 30,000 miles on both sets of OEM tires,, average about 75mph driving on open freeway, during rush hour commutes that drops a lot to more around 60ish average. I don't think I've even ever 100% throttled the car, don't get me wrong, I've defiantly pushed the peddle down a few times when I first got it, but I don't think I've ever been at a stop and smashed it.

So ya, outside of having a lot of L2 charging, I'm just as upset on my SOH as you are.... I had hopped to hang on to this car longer, but given the amount of driving I do if this SOH continues to decline I might have to jump ship.

 

[Kabish]

Idea of the charging I do per month. June/July I was working from home more. September, I don’t know what in the world I did that month lol

 

[flapjake314]

So ya, outside of having a lot of L2 charging, I'm just as upset on my SOH as you are.... I had hopped to hang on to this car longer, but given the amount of driving I do if this SOH continues to decline I might have to jump ship.

yeah doesn't really sound like you did anything out of the ordinary. you are higher mileage for the age but like i said we have higher mileage datapoints with better SOH than you.

with all that said, you're not THAT much lower than the rest of the population. for your mileage the trendline predicts ~92.5% and for your age it predicts ~93%. you're just like 4-4.5% below that, but the trendline itself probably has a stdv of ~2%...

 

[Teslaeata]

I think the important metric is full charge cycles. The data he presented shows the battery will drop to 80% SOH after approximately 1,200 full charge cycles. Use conservatively 200 miles per charge cycle, that's around 240,000 miles. Most people don't keep their cars for 240,000 miles.

It's a non issue.

?

97,000 miles in 39 months and I only charged to 100% 550 times as a generous estimate so doubt the 100% charge cycle will affect virtually anybody??‍

So those looking for reasons/excuses need to look further than 100% charges, and as I must have DCFC charged 150 to 200 times for my c8,000kWh DCFC power, not sure they can use DCFC as an excuse either.

I’m only 6% down on SoH on my usage & charge regime.

 

[Zardoz]

I think the video actually states for the mach-e by and large it shouldn't cause any significant problems outside the temperature situation because ford is so conservative our max charge rate is only like 1.5C and it doesn't hold that long, likes 1C much better.

I totally agree. And you have to use the car, meaning fast charging is something that needs to happen in certain situations. Since temperature is the only thing in our control when fast charging, why don't we have a better pre-condition option? It makes charging faster AND preserves the battery health.

 

[devmach-e]

OBD Scanner and I guess I lied 11.5% but close enough!! I also, in the past year, changed to 85% SoC. I read someplace on here that 80% was not letting the car get updates. I changed to 85% and got like 4 updates pretty quickly. Could had been a coincidence could had been the 85%.

You are going to get misleading data with the battery & outside temperature that high. Recommendation is to discharge the car down to less than 20%, do a full charge to 100%, let the car sit at 100% for at least a few hours and at an outside temperature of 75F or less. This will get you a much more accurate state of health.

The issue with not getting updates had to do with the SOC of the 12V battery, not the high-voltage battery.

Edit to add https://www.macheforum.com/site/threads/hv-battery-calibration-procedure.23815/ calibration process.

 

[Kabish]

You are going to get misleading data with the battery & outside temperature that high.

Thanks for the info! I’ll run through that process once it starts to cool down, hopefully next month.

 

[lwilliams0514]

out of the nearly 100 datapoints i have collected thus far, only 1 person was lower than your SOH. that person was at 87% with 64k miles on the odometer. how many miles do you have and what's the build date of your car?

i'll note lwilliams is at 123k miles and still at 93.5% SOH

if your SOH is truly correct (some people say you need to do a deep charge every month to get an accurate %) you are one of the lowest SOH around. if you think there are any habits or reasons that contributed to that let me know and i'll keep an eye on it from other users in my dataset.

and feel free to enter your data point into my post to track yourself going forward and compare against others.

At almost 126k and still at 93.5% lol

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