stephenjohnson713
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Joined: Tue Jun 30, 2020 2:35 pm

Checking Battery Health for Used i3

Wed Jul 01, 2020 6:44 am

Is it possible or reasonable to ask the dealer to provide a detailed report on the battery condition? I was recently told no by the dealer I'm currently working with. I am familiar with going into the dash controls and getting the Batt. Kapa. Max. and I did that for the 60 Ah car I'm looking at. The Batt. Kapa. Max. was 17.5 which I guess is pretty good for a 2016 i3 with the usable being 18.8 kwh.


I was a little surprised that the dealer could not furnish something since the battery condition is such an integral part of the car. Of course it's still under the battery warranty so maybe he doesn't think it's a big deal.

Am I handling this the right way or should I press for more information on the battery health?

jlangham
Posts: 70
Joined: Sun Nov 04, 2018 6:01 pm

Re: Checking Battery Health for Used i3

Wed Jul 01, 2020 8:27 am

They don't publish that info. Especially if you are buying. I had mine checked at the dealer, and he didn't show me any details of the report. Just said "it's 92%" and just had to "believe" him on that. Not that he would be deceiving me on purpose, it's just that if a test is performed, I want to see the details of the report.

So, no, you won't get any "number" from anyone. Just the Battery Kappa, and mine said 12.5, but the BMW dealer said my battery was 92%?

3pete
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Re: Checking Battery Health for Used i3

Sat Jul 04, 2020 2:31 pm

Agreed that dealers are vague/ secretive about battery health. I honestly think it may be that BMW keeps them in the dark as well and tells them to just listen to what the diagnostic computer says. i3s are still new/rare enough that (most) dealers may not have built up enough experience to know when to question the computer?
jlangham wrote: So, no, you won't get any "number" from anyone. Just the Battery Kappa, and mine said 12.5, but the BMW dealer said my battery was 92%?
Is your 12.5 a consistent number? If you fully charge up to 100% from something below 50% and check it do you get a similar value?

Alternatively, if you check your batt. ladung values in the secret menu do they agree with the 12.5 total capacity as well? For instance at 40% SOC if you had Batt. Ladung of 5kWh would be 5/0.4 = 12.5 kWh total capacity. If that's consistent, I would try and push the dealer for more information because that seems to be below 70%!

When they tested mine, the computer readout lined up pretty close to my Batt Kapa max and my other calculations, but they were not willing to give me an actual result beyond "it passed" so no percentage for comparison or anything.

jlangham
Posts: 70
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Re: Checking Battery Health for Used i3

Wed Jul 08, 2020 5:10 am

3pete wrote:
Sat Jul 04, 2020 2:31 pm
Agreed that dealers are vague/ secretive about battery health. I honestly think it may be that BMW keeps them in the dark as well and tells them to just listen to what the diagnostic computer says. i3s are still new/rare enough that (most) dealers may not have built up enough experience to know when to question the computer?
jlangham wrote: So, no, you won't get any "number" from anyone. Just the Battery Kappa, and mine said 12.5, but the BMW dealer said my battery was 92%?
Is your 12.5 a consistent number? If you fully charge up to 100% from something below 50% and check it do you get a similar value?

Alternatively, if you check your batt. ladung values in the secret menu do they agree with the 12.5 total capacity as well? For instance at 40% SOC if you had Batt. Ladung of 5kWh would be 5/0.4 = 12.5 kWh total capacity. If that's consistent, I would try and push the dealer for more information because that seems to be below 70%!

When they tested mine, the computer readout lined up pretty close to my Batt Kapa max and my other calculations, but they were not willing to give me an actual result beyond "it passed" so no percentage for comparison or anything.
As I stated, my 12.5 was from fully charged. I then took it to the dealer and they said my battery was at 92% - did not match what the secret menu Batt Kappa said.

I don't like that BMW keeps all the info to themselves. Nissan, through the Leaf Spy app, on the other hand, gives great details to their users. My workmate, who talked me into this electric car stuff, has a Leaf. His 2017 battery went below 70% under warranty. He was continually monitoring it. When it hit, he took it to the dealer. Because they both had the same information, the dealer replaced the battery no problem. In fact, he got a bigger battery, so now his range doubled!!

If BMW did the same, I think more people would be inclined to buy them. It's a good car, and as I said, I'm not worried about my battery any longer. People on here are getting themselves wrapped up in the Battery Kappa value, but I still don't believe it matches 100% of what BMW is using to determine "battery health."

Torilatina
Posts: 1
Joined: Mon May 31, 2021 8:39 pm

Re: Checking Battery Health for Used i3

Fri Jul 16, 2021 3:25 pm

Hello,

My used 2015 i3 with REX showed 14.2 is that a good number? I'm so new to this and have no idea. Could someone provide some info?

alohart
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Joined: Sat Nov 01, 2014 7:36 pm
Location: Honolulu, HI

Re: Checking Battery Health for Used i3

Fri Jul 16, 2021 6:04 pm

Torilatina wrote:
Fri Jul 16, 2021 3:25 pm
My used 2015 i3 with REX showed 14.2 is that a good number? I'm so new to this and have no idea. Could someone provide some info?
The Batt. Kapa. max value is a calculated estimate of the usable capacity. On our 2014 BEV, Batt. Kapa. max has varied more than 2 kWh up and down over a short period of time even though the ambient temperature where I live varies by only ~10 ºF between winter and summer (tropics). So one needs to read Batt. Kapa. max over a period of time to get a better estimate of the usable capacity. An alternative would be to use the iOS mi3 app, the Android Electrified app, or BMW's desktop software, ISTA+, to get a more complete picture of what's happening with the battery pack.

The nominal new usable capacity is 18.8 kWh, so 14.2 kWh suggests a 25% usable capacity loss which isn't very good unless your i3 has been driven a very long distance over its life. The usable capacity has to decrease by more than 30% for the battery capacity warranty to apply. If your car hasn't been driven very far, it's possible that it could qualify for a battery pack replacement under warranty before the warranty expires.
Aloha,
Art

2014 BMW i3 Arravani Grey, Giga World, Tech + Driving Assist, Parking Assist, DC Fast Charging, JuiceBox EVSE

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MKH
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Re: Checking Battery Health for Used i3

Sat Jul 17, 2021 6:28 am

My used 2015 i3 with REX showed 14.2 is that a good number? I'm so new to this and have no idea. Could someone provide some info?
What range are you getting, and under what driving conditions?
Mark H.
2015 i3 Rex, Capparis White, Tera World, Technology & Driving Assistant, Parking Assistant, Harman Kardon Audio System, 19 inch Rial X10-i wheels, EVoInnovate EVSE

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MKH
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Re: Checking Battery Health for Used i3

Mon Jul 19, 2021 12:55 pm

The nominal new usable capacity is 18.8 kWh, so 14.2 kWh suggests a 25% usable capacity loss which isn't very good
Not sure how much I trust battery kappa readings. After a month or more of daily short trips (15 miles), with no preconditioning set or used, recharging daily or every two days, was seeing a decrease in range to about 55 - 58 miles on average, temps in the mid 90s F, Comfort mode, AC on, battery kappa reading - 14.3 kWh.

Over the weekend, did a long trip, taking the battery down to 6 miles left in range, set precondition and recharged overnight, range this morning was 69 miles - only 3 miles off 'new' advertised range of 72 miles, with a battery kappa reading of 15.
Mark H.
2015 i3 Rex, Capparis White, Tera World, Technology & Driving Assistant, Parking Assistant, Harman Kardon Audio System, 19 inch Rial X10-i wheels, EVoInnovate EVSE

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