User avatar
MKH
Gold Member
Posts: 635
Joined: Fri Nov 02, 2018 5:48 am
Location: Dallas

Re: Battery Replacement Under Warranty

Sat Sep 12, 2020 4:12 am

HI my max kappa value is currently is showing 13. my I3 is a 2015 model. Do you think BMW will honor the warranty just based on the kappa value alone. So far on a good day, the max mileage on a full battery is 55 miles.
Short answer - no.

The battery kappa is a 'guess' using an algorithm that calculates the kappa based on conditions at that time. It changes.

Is yours a REx or a BEV? Makes a difference. REx stated mileage is 71, BEV 83. Using 55 as your mileage you are at 76% if REx and 67% if BEV, but the only way BMW will entertain a warranty replacement claim, is if they fully test the battery, which entails draining the HV pack to zero, then measuring the charge it takes to take it up to 100%.

Is your mileage consistently low? Mileage changes according to driving style and temp. On days when the temp is 100+ F (so the AC is working hard full-time), and I drive a little aggressively, my range - 2015 REx - can be as low as 55. Below 80 F, and drive a little more sedately, and my range will be 70+.
Mark H.
2015 i3 Rex, Capparis White, Tera World, Technology & Driving Assistant, Parking Assistant, Harman Kardon Audio System, 19 inch 427 wheels, EVoInnovate EVSE

alohart
Posts: 2121
Joined: Sat Nov 01, 2014 7:36 pm
Location: Honolulu, HI

Re: Battery Replacement Under Warranty

Sat Sep 12, 2020 12:24 pm

Magiclamp wrote:
Sat Sep 12, 2020 12:36 am
HI my max kappa value is currently is showing 13. my I3 is a 2015 model. Do you think BMW will honor the warranty just based on the kappa value alone. So far on a good day, the max mileage on a full battery is 55 miles.
All accounts that I've read indicate that BMW doesn't consider the Batt. Kapa. max value when deciding whether to replace the battery pack under warranty. A BMW dealer would have to perform its own lengthy battery pack capacity test which involves fully charging and discharging the battery pack while measuring the energy added or removed from the battery pack. The dealer would charge for this diagnosis which could be several hundred dollars. This diagnostic fee would not be charged if the usable capacity were determined to be less than 70% of the new capacity.

What I plan to do is to charge fully, reset the trip meter, drive until the charge level is as low as possible without risking running out of charge, and then reading the consumption rate (mi/kWh) for this trip. Dividing the distance driven by the consumption rate would be the usable capacity in kWh. I don't know how accurate this would be, but if it is less than 13 kWh, I would be willing to pay a dealer for the usable capacity test.

A big problem with all of this is what the battery management system (BMS) is doing. It can apparently dynamically adjust the usable capacity by changing the size of the high and low charge level unusable buffers. The dealer's maintenance software can apparently restore the original sizes of these buffers which results in greater usable capacity, at least for a while before the BMS adjusts it again. Several i3 owners have reported paying for the diagnosis and being denied a battery pack replacement because the usable capacity had been increased enough by the dealer to avoid a warranty claim.
Aloha,
Art

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

Magiclamp
Posts: 10
Joined: Fri Jul 06, 2018 11:58 am

Re: Battery Replacement Under Warranty

Mon Sep 14, 2020 10:55 pm

Based on ur formula, i am only getting 12.5 kap. Did it 2x and both time getting the same result.

Return to “Technical BMW i3 Discussions”