3pete
Posts: 156
Joined: Tue Mar 19, 2019 9:03 pm

Re: Charting Battery Capacity/ State of Health Over Multiple Years

Sun Oct 10, 2021 3:18 pm

An update from a few months later:

Image

My Batt. Kapa Max values seem to be holding around 15 or so and the other metrics I track seem to agree that there was a bump in battery capacity from the software upgrade. This makes me think that BMW indeed programmed some "conservative" parameters into the initial BMS which have since been loosened up in an update.

That's completely understandable since they were dealing with an unproven technology but they should offer a software upgrade to anyone with an older i3 if that is indeed the case.

I'm open to other theories if anyone has any thoughts?

alohart
Posts: 2450
Joined: Sat Nov 01, 2014 7:36 pm
Location: Honolulu, HI

Re: Charting Battery Capacity/ State of Health Over Multiple Years

Sun Oct 10, 2021 11:09 pm

What is the system software version (a.k.a., integration level) of your i3 after the update? If the BMS has been updated in recent software versions, I might be willing to pay our BMW dealer to update the system software on our 2014 BEV whose Batt. Kapa. max value has dropped to ~15 kWh after having been driven only 12k miles.
Aloha,
Art

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

3pete
Posts: 156
Joined: Tue Mar 19, 2019 9:03 pm

Re: Charting Battery Capacity/ State of Health Over Multiple Years

Mon Oct 11, 2021 3:22 pm

alohart wrote:
Sun Oct 10, 2021 11:09 pm
What is the system software version (a.k.a., integration level) of your i3 after the update?
During the capacity check I went from: I001-17-11-543 to: I001-21-03-530.
alohart wrote:
Sun Oct 10, 2021 11:09 pm
If the BMS has been updated in recent software versions, I might be willing to pay our BMW dealer to update the system software on our 2014 BEV whose Batt. Kapa. max value has dropped to ~15 kWh after having been driven only 12k miles.
I can't say definitively that the software upgrade changed the BMS logic, but it seems to make sense to me. Art, yours would be a very interesting case with such low mileage and such an ideal climate for an EV. I wonder if you could convince your dealer to upgrade/ check "for science" to report back to the BMW mothership. With the chip shortage and so few new cars to sell, I'm sure they're bored and looking for something to do :lol:

alohart
Posts: 2450
Joined: Sat Nov 01, 2014 7:36 pm
Location: Honolulu, HI

Re: Charting Battery Capacity/ State of Health Over Multiple Years

Tue Oct 12, 2021 12:32 am

3pete wrote:
Mon Oct 11, 2021 3:22 pm
During the capacity check I went from: I001-17-11-543 to: I001-21-03-530.
Thanks! It would really be nice to know what changes in each software update. The fact that BMW is apparently still releasing an i3 software update every 4 months makes me wonder what is changing. I'm guessing that the changes affect mostly recent i3's and not old ones like mine.

I can't say definitively that the software upgrade changed the BMS logic, but it seems to make sense to me. Art, yours would be a very interesting case with such low mileage and such an ideal climate for an EV. I wonder if you could convince your dealer to upgrade/ check "for science" to report back to the BMW mothership. With the chip shortage and so few new cars to sell, I'm sure they're bored and looking for something to do :lol:
… or looking to separate me from my money :D

When I return in mid-November, the annual state safety inspection will be due. I might as well let our BMW dealer perform this inspection because it's a fixed cost no matter where it's done. When I talk to the service advisor, I could plead my case and learn the cost for a software update if they won't do it at no cost. Another local i3 owner did get a capacity check including a software update at no cost, so there's hope. I don't really need more range, but it would be nice to have some additional range on occasion.
Aloha,
Art

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

Arm
Posts: 159
Joined: Tue Jan 07, 2020 5:53 pm

Re: Charting Battery Capacity/ State of Health Over Multiple Years

Wed Oct 13, 2021 11:26 am

I bought my 2018 i3S with 43500 miles on it on 9/4/2021. At the time, I checked the Kappa and it read 29.2 kWh. It was bang in the middle of summer and it was a hot day. I don't recall what the SOC was at the time or if the car was charging. But I do know the temperature was well in the 90's.

I checked my vehicle today (11/13) and I got the following:

Kappa = 28.8
OA Temp = 69.5F (in a garage)
Coolant Temp = 118 C (not plugged in...can't make sense of this reading)
Batt Temp = 71.6 F
SOC = 93%
Current Miles = 44500

I take the approach of almost always having it plugged in. I feel it's better for the battery to be conditioned the way it was intended by design. That said, I do not know how the car was treated prior to my purchase. I do know the overall condition of the car was good and I am assuming the car did a lot of freeway miles given the fact that it averaged 15k miles a year. So I would assume there were quite a few fast charging sessions involved given it's a BEV. The original purchase location of the car was Palm Springs 3 years ago which is roughly 120 miles away from where I am.

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