Oleksiy
Posts: 30
Joined: Fri Mar 23, 2018 4:30 am
Location: Kyiv, Ukraine

Re: 2015 i3 Battery Degradation (20% after 30k miles)

Tue Sep 04, 2018 1:53 pm

EVMan wrote:How do you take this temperature reading of the pack ?

It's in the hidden menu, "14.05 Batterietemp" subitem.

I believe my pack's 86F is ok, but we've had quite low summer ambient temperature this year. Just wondering how the battery behaves under 110F Arizona weather.

Oleksiy
Posts: 30
Joined: Fri Mar 23, 2018 4:30 am
Location: Kyiv, Ukraine

Re: 2015 i3 Battery Degradation (20% after 30k miles)

Tue Sep 04, 2018 2:06 pm

EVMan wrote:While the pack re-initializing will have an immediate effect on readings, sooner or later it will catch up on the actual status of the battery.
Cycle complete battery from full to 0 , will also kind of re-initialize.


Did you try to complete such a cycle? Any success in increasing Batt.Kapa?

I'm not sure the BMS reports the actual satus of the battery correctly. So once my pack's capacity goes down to 16 kWh according to the car's self-reporting, I'd be happy to have the battery reinitialized so that I have 17+ again, corresponding to the real capacity at the moment other than relying on some guestimate by BMS.

This is what happened to 30 kWh Leaf. Recently Nissan has circulated a firmware upgrade, and people saw their capacity increased by 1-2 kWh with the corresponding increase in range. Eventually, this added capacity will fade away as well. Only now it will fade from 17+ to 16 kWh rather than from 16 to 15 (based on i3 numbers).

alohart
Posts: 1350
Joined: Sat Nov 01, 2014 7:36 pm
Location: Honolulu, HI

Re: 2015 i3 Battery Degradation (20% after 30k miles)

Tue Sep 04, 2018 7:47 pm

Oleksiy wrote:I believe my pack's 86F is ok, but we've had quite low summer ambient temperature this year. Just wondering how the battery behaves under 110F Arizona weather.

Several hot climate i3 drivers have reported lost power bars/limited power after their i3's had been parked in the sun over hot asphalt on a 110+º F day similar to what happens when an i3 battery pack's temperature is very low in cold weather. It would be interesting to know what the battery pack temperature must be for its output power to be artificially reduced.
Aloha,
Art

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

alohart
Posts: 1350
Joined: Sat Nov 01, 2014 7:36 pm
Location: Honolulu, HI

Re: 2015 i3 Battery Degradation (20% after 30k miles)

Tue Sep 04, 2018 8:11 pm

Oleksiy wrote:I'm not sure the BMS reports the actual satus of the battery correctly. So once my pack's capacity goes down to 16 kWh according to the car's self-reporting, I'd be happy to have the battery reinitialized so that I have 17+ again, corresponding to the real capacity at the moment other than relying on some guestimate by BMS.

Because the displayed charge level percentage is a calculated rather than a directly measured value, it can be inaccurate. Maybe reinitializing is recalibrating the displayed charge level percentage so that it is more accurate. If so, reinitializing could result in a gain or loss in usable battery pack capacity. An inaccurate displayed charge level percentage could result in an inaccurate Batt. Kapa. max value assuming that its algorithm extrapolates the energy added during charging over a partial inaccurate charge level range to the full 0% to 100% charge level range.

Or maybe reinitializing is cell charge level balancing that dealers can do with specialized equipment much more rapidly than an i3's built-in balancing. That would increase the usable battery pack capacity if significant cell charge level imbalance existed.
Aloha,
Art

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

EVMan
Posts: 207
Joined: Sat Feb 25, 2017 4:31 pm
Location: USA, CA

Re: 2015 i3 Battery Degradation (20% after 30k miles)

Wed Sep 12, 2018 9:55 pm

Oleksiy wrote:
EVMan wrote:How do you take this temperature reading of the pack ?

It's in the hidden menu, "14.05 Batterietemp" subitem.

I believe my pack's 86F is ok, but we've had quite low summer ambient temperature this year. Just wondering how the battery behaves under 110F Arizona weather.


So , i have observed , when i start i3 in morning, sometimes the battery cooling AC turns on , and some times not.
While it is likely to happen , when its hot , it kind of happens randomly , even on cold days.

If any one observed , any patterns for, the battery cooling AC turning on with the battery temperature , do comment.
I have not observed any pattern with the California weather , except for , when its really cold.
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