EV battery degradation over time

sh81722

https://www.boards.ie/discussion/comment/121319752#Comment_121319752

The inverter actually does AC to DC conversion when topping up the battery from the wall which is the case most of the time. Having your estimated 20/25% losses one way when charging the battery (remember it's just one way in OP's case) is probably about 5-10 times the actual value.

Edit: Well maybe not that much. We'll say 2-3 times.

BKtje

I don't have a BEV but a PHEV with a 15.6kw/h battery (10.6 usable). I mainly used public chargers and I even have DC charging (up to 21kw) which was used daily for the first year.

The all electric range is more or less the same as when I bought it 3 years ago and for the first 2 years of life the battery was fully charged twice a day. This is backed up by the amount put into the battery as per my app logs (between 12 and 12.5kw/h as measured by charger) per full charge. The battery degradation seems minimal though I don't know if the Mercedes software eats into the unusable space a little to keep the range "stable".

The lease is up next year and I plan to request the battery health at that point (should have asked at the service last week to be honest). I've been incredibly happy with its performance and gives a lot of weight toward getting a Mercedes BEV when I eventually switch.

sh81722

https://www.boards.ie/discussion/comment/121320369#Comment_121320369

It's from home assistant, sunsynk add-on, via the RS485 port. Renewables forum probably have more details.

sh81722

https://tm3een.home.blog/2020/12/29/efficiency-when-home-charging-at-11kw/

I know the OP has an ID.x but here is a blog I came across on the wall to battery charging efficiency. His results indicate losses of 1.8 to 4.7% on various charging sessions at home including the cable run from the meter. So he loses on average 2 kWh when charging 60 kWh. A far cry from 15 kWh lost suggested here.

Furze99

I think what the OP is at, is how to empirically/ independently check battery degradation. Be unwise to rely on what any particular car manufacturers software reports etc.

kanuseeme

https://www.boards.ie/discussion/comment/121320727#Comment_121320727

you said 15kwh,

SharkMX7:37 am

'' https://www.boards.ie/discussion/comment/121318299#Comment_121318299

I doubt they are. If the car is given 58kwh with only a 10% loss the car is only getting 52kwh into the battery.

More like 15% loss for me though when charging when i tried to measure the loss.

Good explanation here where they say the losses are somewhere between 10 and 25% when charging. If its 25% the OP will be unhappy to hear that his battery has only taken 43kwh on that charge.

https://go-e.com/en/magazine/ev-charging-losses

So you reckon we lost 15 kWh as heat on that session? Something in his setup must have been running red hot for those 8 hours the charge took''

I said 19% from my experience with a BMW, others have tesla at 6 and 8%, the Merc is at 20%, I would tend to believe those tesla figures, as tesla cars are efficient,

The question is for VW and its loses while charging, the OP had no clue on allowing even for 10% which I had accepted as standard till I checked my own app.

I highly doubt its as good as a Tesla and would believe its closer to BMW or Mercedes in efficiency.

sh81722

https://www.boards.ie/discussion/comment/121320948#Comment_121320948

What I said was that charging losses of up to 25%, which in case of 58 kWh battery is approx 15 kWh, is ridiculous and I asked SharkMX if in his opinion this makes sense.

You then said: "A quick calculation puts the id3 pack at around 300 litres in volume, its designed for liquid cooling, so its not insulated , I would imagine 15kwh spread over 8 hours would not be noticeable".

In my opinion it would be very noticeable compared to the real loss of about 3% which is a small handful of kWh based on the blog post I posted.

Do you still think that upwards of 15 kWh lost in charging process of a 58 kWh battery is not a totally ridiculous amount of energy that would not noticeably heat up the equipment over a 8 hours charging session? 🤣

Ev fan

https://www.boards.ie/discussion/comment/121319881#Comment_121319881

Only 1.3% degradation on that mileage/ age is exceptional- sounds like you have an excellent battery and BMS. Did the SOH reading come directly from the car or other measurement means?

Ev fan

https://www.boards.ie/discussion/comment/121320660#Comment_121320660

You make a very interesting point about the buffer (non usable) energy- 5 kWh in your case which is very sizeable. At what point might it be released to compensate for some degradation in the usable part of the battery. Looking at the VW situation- 58kWh with 62kWh gross- at some point the battery will degrade to below 70% SOH. Knowing VW I think this won't happen in the vast majority of cases to well over 160000 kms mileage. My question is will they simply unlock the buffer at that stage to bring the battery above 70% rather than repairing/ replacing expensive modules?

Rusky rusky

The charging losses should be around 10% on AC. Below an example of charging losses for my MY. Wallbox reported 32.59kWh, Tessie shows 30.54kWh used and 29.52kWh charged. So 29.52/32.59 = 90.6% or 9.4% losses.

Also, I had 6.3% degradation with ab 40k km when the ID.3 1 ed was 2.5yo. This was measured by VW when they replaced 2 battery modules (that was a year ago). Chris from Battery Life reported ab 9% degradation after 3 years. And VW was cheeky to advertise as 58kWh usable while.in reality no one ever saw more than 54kWh due to hidden buffers.

Jackben75

https://www.boards.ie/discussion/comment/121318383#Comment_121318383

is that not a serious bump for resale value though?

zg3409

For the average enthusiast querying the battery management system (BMS) for state of health (SOH) using an odb dongle and a phone app will get quite close to the true value and will be very closely related to manufacturer warranty.

Next Eco car/ Aviloo offer and indepedent test but it takes multiple full charge discharge cycles and it's probably relatively expensive and it's likely manufacturers may not believe their result for warranty.

https://www.nextecocar.ie/about-us

These DIY charge discharge tests are not really scientific enough. You cannot see hidden buffers, and hidden buffers may be released as car ages, again masking degredation, so it's hard to know until significant degredation exists. I think most modem EVs will see little noticeable degredation up to 200,000km so it will not be an issue for most. Larger batteries also mean the number of full discharge cycles are likely to be less compared to older EVs.

kanuseeme

https://www.boards.ie/discussion/comment/121322666#Comment_121322666

ID3 inverter, those cooling pipes are on it for a reason, its not the only component in the car, I imagine the battery also, its 15kwh over 8 hours so a little under 2 per hour, its not an insulated domestic water tank, its designed to dissipate heat, I would believe that it could lose heat just as fast gain it, so while its a ridiculous amount of heat or wastage, I believe its possible, I believe VW just stuck any inverter in, just to start producing the ID range,

Another thing is efficiency at charging speed, I was looking at pc power supply units, more efficient at higher loads, up to 90% while idling its 80%, maybe the car would be more efficient charging at 11kwh,

my own case 19% it was charging at 1.6 kw or so, I will ramp it up to 3.7 kwh and see if it makes a difference.

slave1

https://www.boards.ie/discussion/comment/121324427#Comment_121324427

Most manufacturers will only replace with a remanufactured battery that will get you over the 70% mark, unlikely you would get a brand new battery.

Tesla deffo replace battery failures with remanufactured and it's a lottery, plenty of 2015/2016 Model S cars with 2014 batteries in them and also those lucky ba$tard$ with a brand new 90battery fitted to 85 models, the so called lottery winners

kieran.

https://www.boards.ie/discussion/comment/121323040#Comment_121323040

It was in for service last week so I asked for a battery health report. Thats the print out from the garage.

liamog

https://www.boards.ie/discussion/comment/121331144#Comment_121331144

It's pretty normal for Hyundai/Kia cars. They've generally over provisioned batteries to allow for minimal degradation during warranty periods. The first example was with the Kia Soul, you started at 110% battery health which dropped over time. Later they capped the system to report a max value of 100%. There reasoning seemed to be if I sell you 50kWh of usable battery and you can still use 50kWh then your at 100% of what you were sold. The customer doesn't need to know they were originally provided with a 55kWh battery. I don't know if they still do this with the newer models such as Ioniq 5 and EV6.

Other manufacturers took a different approach where they said the consumer should be able to use the "full" capacity of the battery from day 1, but will have an apparent reduction in capacity pretty quickly. Personally I prefer the Hyundai/Kia approach as I think it's easier for the average consumer to understand.

SharkMX

https://www.boards.ie/discussion/comment/121322666#Comment_121322666

No, you are assuming people said 15kwh. You made that up yourself. Read the thread again.

liamog

https://www.boards.ie/discussion/comment/121331426#Comment_121331426

https://www.boards.ie/discussion/comment/121318314#Comment_121318314

An up to 25% charging loss on a 58kWh pack is 14.5kWh, close enough that enough for it to not be unreasonable for someone to ask you where do you think the 15kWh is going and why isn't it noticeable.

You introduced the possibility based on your linked article.

SharkMX

https://www.boards.ie/discussion/comment/121331572#Comment_121331572

Not reading the posts correctly and assuming people are telling you a figure. Thats what someone else pointed out to him earlier in the thread. Then he goes and says that they are choosing a specific figure that they didnt either.

This is the problem with threads on these things.

kieran.

https://www.boards.ie/discussion/comment/121331207#Comment_121331207

The battery of the Kia e-Niro 64 kWh has an estimated total capacity of 67.5 kWh. Given that, the reduction would be approx 6.4% which is not to shabby for my milage to date .

kanuseeme

I am more concerned/interested in actual loss while charging, if that is understood then its very easy to calculate degradation, at the moment I tend to believe Tesla at less than 10%, my own car I forgot to turn off the pre conditioning this morning, I will charge tonight at max and see if its an improvement over 19%.

I would like to know the figures for Telsa when charging at 11 kw, to see if its more/less efficient at different speeds.

liamog

https://www.boards.ie/discussion/comment/121331592#Comment_121331592

If you put a statement saying a 58kWh car only takes 43kWh based on a 25% loss then you have introduced 15kWh of lost energy, that's from your own post. It's not an assumption to take a figure from your post but go the extra step of subtracting 43 from 58 and getting 15.

It looks like the 25% figure comes from an approximation of ADAC charging a Zoe on a granny charger (24.2%). They got much better numbers charging at higher AC rates from a wallbox.

This somewhat matches @kanuseeme's reported numbers where they are seeing high losses charging at low rates. My guess is that there is a floor number where a certain amount of energy is needed to keep the system operating and battery at a temperature. If you are charging for a longer period of time then more energy is used keeping the systems up than is lost due to AC/DC conversion.

Ev fan

https://www.boards.ie/discussion/comment/121331661#Comment_121331661

I think what liamog has said makes more sense to me ie that you started out at higher capacity than the stated nominal capacity. This allows then for latent degradation that is not evident in SOH reporting. You can't deny physics although who's to know that there won't be significant upgrades to batteries/ BMS systems in the future that will minimise battery degradation over time. Coincidentally I came across a very interesting report from clean-technica. It examined the battery degradation impact on Tesla cars which were largely fast charged versus largely slow charged cars. Interestingly Tesla Model 3's showed an average degradation of 11% after 5 years. Tesla model Y's showed an average degradation of 9% after 3 years. Guess what though- they concluded that there is little to no difference in impact between fast and slow charging over time on battery degradation. This result was for Teslas- but should we expect it to be any different for other main brand EVS?

SteelyDanJalapeno

OP here with a follow up to a very non scientific experiment which I am not claiming as anything more than interesting, there's the disclaimer out of the way for the contrarians.

So 0-100% charge took 58.5kws according to my Zappi CT clamp.

Over the weekend I ran this down to 2% and crudely measured the energy consumed based on the average per 100km value multiplied by the distance covered, I fully understand this is not a solid indication of SOH, for that I have booked in with VW for a health check using there ODIS tool on my next service in December.

Nevertheless here's the data from the weekend

Distance covered 324km + 7km left ( I know gom, could be higher or lower, let's assume)

Averaged 15.7kwh/100km

15.7 * 331 = 51,96.7kws

58.5 - 51.967 = 6.533kws missing from how much energy I used to charge it versus how much energy I used to get back down to empty

I'm not privvy on how accurate their on screen data is, but it's safe enough to say the max degradation my battery has is 11% based on that, however I think it's probably a lot less as I ran with heating for a lot of the trip and I didn't see this increase the average, so is this solely based on distance? Any way more will be revealed in December!

kanuseeme

ok I tested charging my car at max, 4% to 100% @ 3.6 kw, usable is 8.8 and the app reports 9.66 so nearly 10% loss while charging, much better than the 19%

It could still be more than 10% as it does not take into account degradation, my car only has a 1.2 kwh of a buffer.

Lesson learned, to charge at max rate, it brings to mind of trickle charging off solar as it might not be the best use of energy.

I think the OP is safe enough to assume under 10% charging loss,

kuro2k

I have a 2019 Kona 64 kWh which now has 93k.

I have used Car Scanner to track the degradation since 58k, usually taking a screenshot of the app results every thousand KM. I asked the dealership to perform a battery health check at 92k and the sate of health % was identical to the Car Scanner app result i was getting.

The original battery was replaced in April 2022 when the car had 63k and state of health was 93.4%. We used fast chargers and charged to 100% a lot for the first year on the original battery.

The state of health of the replacement battery battery is now at 93.8%, it has never used a fast charger and is very rarely charged to 100%.

Very disappointed the replacement battery is degrading twice as fast as the old one did, raised it with the dealership so waiting to hear back.

SteelyDanJalapeno

https://www.boards.ie/discussion/comment/121351319#Comment_121351319

Curious what caused the battery replacement?

innrain

https://www.boards.ie/discussion/comment/121352565#Comment_121352565

There is a worldwide recall for those batteries.

https://www.ccpc.ie/consumers/product_recalls/hyundai-recalls-certain-kona-passenger-vehicles/

Zurbaran

I'm pretty sure the motors will go before the batteries in most cases.

Do we know who has the most reliable motors? Its not something I ever see being discussed.

jlang

Motors likely cheaper to buy and to replace than batteries so less of a worry.