From 84% to 78% suddenly

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christosp

Member
Joined
Feb 11, 2022
Messages
10
Hello all,

Today I charged my i3 (2014 bev) at 100%. Usually I charge my i3 from 20% to ~80%.

Everything looked good. I run 20km and the battery went from 100% to 85%. ( here in Greece we had about 13 celcious today).

At 85% I parked the car. When I opened it again it was down to 84.5%. After 1km of driving the percent fall down to 78%.

The last 1 month (the coldest month of the year so far ) this has happened again 3 times but only after charging :

From 85% to 79% after charging without moving the car.
From 77% to 74% after charging without moving the car.

I am feeling that something goes wrong as the past 3 years I own the car, nothing similar happened.

For your info my i3 until now gives me 120-135km per charge (135 at the summertime). My warranty ends in one and a half month from now (8years battery warranty).

Anyone with the same problem?
 
14.8 indicates about 78% capacity, or 22% degradation, but it's an unreliable number and should be tracked over time.

Battery % state of charge can also be unreliable. The battery will rebalance its cells and recalculate the displayed % SOC. Charging to 100% gives the BMS a good recalibration point. SOC at lesser charge levels requires use of BMS advanced accounting skills and assumptions.

Cold weather could be playing a factor as well they additional heat use.

Ultimately it comes down to how far you can drive on a charge. The car's consumption calculations are accurate, so the next time you have the opportunity, start with a full charge and see how far you can drive. No need to run it down to 0 -- you can calculate the remainder, then work backwards using the average consumption for the trip to estimate your battery's real capacity.
 
Thank you for your reply. I knew that the guesstimate may be unreliable but didn’t know about the % of the battery.

The range all these times seems to be right. For example one of these times from 83% to 56% i3 gave me more than 40km.

So you suggest not to be worried? I am a little bit anxious because my warranty ends soon.
 
No, I'm not suggesting not to be concerned about your battery's health, only that it's not reliable to simply go off of estimated range or % SOC jumps.

The sad truth from what I've read over and over on these forums, reddit, and Facebook, is once an owner thinks they've hit that magic 70% threshold, they take it in, pay the cash for the requisite software update and test, only to be told "your battery is fine" (fine meaning 71% or better). When that owner goes back to the numbers they were using previously to make their determination, they find the indications all look slightly rosier than before BMW touched it.

But who knows? Perhaps updated software will solve the SOC jumping problem you're experiencing, so it may be worth it to look into getting an update.
 
Hello again,

I fully charged 100% my i3 and after 84km I had left with 31% soc. 8 - 11 celcious outside.

That means it can give me about 121km at this temperature.

But the problem continues. So I arranged a mechanical test with the dealer.

What makes me anxious is that as far as I have searched the forums and the groups, nobody reported such a problem. SOC jumps or how else we can name it.

If you have experienced something similar please tell me.

Thank you!
 
It's sounds like you're achieving expected range?

The jump in % SOC could be due to a faulty cell or cells, and the battery rebalancing itself after it's left standing.

Report back what the shop finds. It would be interesting to know how you're getting 121 km from that pack if the kappa max is what the hidden menu indicates and the battery had a bad cell.
 
Hello again,

I have not replied for so long as I wanted to test the charging process after picking up my car from the dealer.

Well, I visited the dealer here in Athens, Greece (company: SPANOS SA).

The first thing they mentioned after the reading of the fob key, is that the 12v battery is almost dead. I checked it by myself at their screen.

I described the problem and the tech guy informed me that this is something (the soc jumps) that happens may happen and that me, as a user of i3, I have to start charging from lower soc once in two months. in order to help the bms calculate better? I am not sure.

Long story short, I decided to leave the vehicle over night, to replace the 12v battery (never changed since 2014) and take a battery test. I have tested the battery capacity before, when I purchased the vehicle 08/2019.

Battery capacity 08/2019: 88%
Battery capacity 04/2022: 78%
To be honest 10% in almost 2,5 years is not I was expected.

I have to mention that I was watching the process through the bmw app at my phone.

Battery test cost: 80 euro
12v cost and replacement: 170 euro

After I received my vehicle, I have charged it 5 times and the soc jumps continue. The difference now is that I feel more confident about my battery health, as I know that I have 78% capacity left.

I am considering do a software update, that maybe help correct the jumps.

Any ideas?
 
About 110 to 120 at winter time (up to 15 celcious)
About 130 at the summer time (more than 15 celcious)

I have not drive it to zero%, but as estimation to my driven kms between charges.
 
So BMW service only provided you the 78% figure? They didn't tell you if the test detected any bad cells? I'm still betting you've got a bad cell in there.
 
Yes they just provided a single page with the percentage on it.

The same paper with the previous dealer at 2019.

I believe it is a default report.
 
christosp said:
Oh sorry, it has 62.000 km


Your 2014 has been very lightly driven for being nearly eight years old!

In thinking that your HV battery hasn't been stressed by driving less than 8000km/year, have you considered charging your BEV to 100%?

BMW designed the i3 so that a displayed 100% SOC means that the i3 has allowed the battery to charge to somewhere in the 90% range (absolute). This provides a buffer to prevent damage – a similar one is in effect at 0%. (i.e. when the SOC says "0%" the battery is not fully discharged).
 
frictioncircle said:
Your 2014 has been very lightly driven for being nearly eight years old!
Our 2014 BEV has been driven less than 13k miles since we bought it new in November, 2014, yet its usable battery pack capacity has decreased by 24% according to the mi3 app and its actual range. Very disappointing. However, with our battery pack warranty expiring in less than 8 months, it's very unlikely that the usable capacity will decrease enough more to qualify for a warranty replacement. Instead, we'll be stuck with an i3 with insufficient range to drive where we occasionally want to go.
 
our battery pack warranty expiring in less than 8 months, it's very unlikely that the usable capacity will decrease enough more to qualify for a warranty replacement. Instead, we'll be stuck with an i3 with insufficient range to drive where we occasionally want to go.

Exactly the same issue the co-worker who introduced me to the i3 is having. Bought his i3 Bev new in 2014, low mileage, now with decreasing HV battery capacity that limits his travels, but likely not enough to trigger warranty replacement before the warranty expires. With used cars in high demand and premium being offered on trades by dealers, he opted to order a MINI Cooper SE electric to replace the i3. With a low base price, and decent range (114 miles) I seriously considered doing the same - as I'm seeing the same kind of HV battery loss, but need more space than the two door SE - waiting to see what the electric MINI Countryman looks like when it comes out later this year.
 
I haven't followed lithium battery longevity that closely so I'm surprised to read the most recent posts that show significant degradation because of how old the battery is as opposed to the number of miles it has been driven.

alohart, according to Metromile https://www.metromile.com/blog/average-miles-driven-per-year-by-americans/, an average Hawaiian driver does just a bit over 11,500 miles per year.

I drove my 2014 BEV from new to nearly 55K miles and I saw about a 25% drop in range on the GOM – 80 miles when new and around 60 miles when I traded her in.

You've driven your 2014 BEV just 13K miles over eight years and it makes no sense that your i3 has lost 24% of battery capacity.

This makes me wonder if BMW's Kappa algorithm is considering a battery's calendar age along with how it's been used.
 
frictioncircle said:
You've driven your 2014 BEV just 13K miles over eight years and it makes no sense that your i3 has lost 24% of battery capacity.

This makes me wonder if BMW's Kappa algorithm is considering a battery's calendar age along with how it's been used.
That's certainly a possibility. If I still own our 2014 BEV after its battery pack warranty expires in November, I plan to "reset" the BMS using ISTA+ 4.10 which has this capability unlike newer versions. Some European i3 owners have increased the usable capacities of their 60 Ah battery packs in this way although apparently the usable capacity slowly decreases again over several months.
 
eNate said:
Lithium batteries degrade over time even if not used.
Yep. I wonder whether our i3 being stored for over ~27 months total for periods of 3 to 9 months each might have accelerated this degradation. Maybe inactive battery cells degrade more rapidly. However, I've not found any scientific literature that supports this.

I know 3 other 2014 BEV owners in Honolulu who've charged their i3's differently, who've driven different total distances, and have driven differently, yet the usable battery pack capacities of all 4 i3's have degraded by at least 25%. One of their i3's managed to fail BMW's battery capacity test even though its Batt. Kapa. max and actual range are no worse than the rest of ours. We plan to meet to generate mi3 reports for all of them to learn whether we can understand why one of these i3's is getting a new battery pack under warranty despite appearing to have a similar usable capacity to the others.
 
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