i3 Battery charging - Degradation real life experience

[alohart]

It's good to try something after you get the car - when I did six months after buying mine, I found that the dealer or previous owner had installed a GPS tracker in the OBD port!

A U.S. i3 would normally sound the alarm a while after it is shut down if an OBD dongle remains plugged in. I don't know how long after shutting down the alarm would sound. I participated in a state of Hawaii pilot program whose goal was to base the annual registration fee on the distance driven with maybe the vehicle's weight considered as well. An OBD dongle was used to transmit distance driven data via a cellular data connection to the DMV. The dongle set off the burglar alarm on our 2014 i3 sometime during the night. To prevent this, the value of the following coding parameter in the Roof Function Center (FZD) could be set to inactive:

OBD socket alarm (BimmerCode expert mode)
3002->OBD-Alarm: active (default)

However, setting this parameter to inactive is considered to increase the risk of an unknown OBD dongle being installed in one's i3. Maybe that change had been made to your i3 when the GPS tracker was installed.

 

[Mondomensch]

A U.S. i3 would normally sound the alarm a while after it is shut down if an OBD dongle remains plugged in. I don't know how long after shutting down the alarm would sound. I participated in a state of Hawaii pilot program whose goal was to base the annual registration fee on the distance driven with maybe the vehicle's weight considered as well. An OBD dongle was used to transmit distance driven data via a cellular data connection to the DMV. The dongle set off the burglar alarm on our 2014 i3 sometime during the night. To prevent this, the value of the following coding parameter in the Roof Function Center (FZD) could be set to inactive:

OBD socket alarm (BimmerCode expert mode)
3002->OBD-Alarm: active (default)

However, setting this parameter to inactive is considered to increase the risk of an unknown OBD dongle being installed in one's i3. Maybe that change had been made to your i3 when the GPS tracker was installed.

Now that you mention it, I was getting spurious alarms, but perhaps that was related to super hot summer days. I have only tried BimmerLink so far but will try BimmerCode at some point in the next few months. In any case, no dongle installed now.

 

[Clanduncan]

Same one I bought in the UK. Works well with the Electrified app, and also allowed me to code my car (with Bimmercode) when I changed the main screen up to a 10.25" unit.

 

[Gonville]

A U.S. i3 would normally sound the alarm a while after it is shut down if an OBD dongle remains plugged in. I don't know how long after shutting down the alarm would sound. I participated in a state of Hawaii pilot program whose goal was to base the annual registration fee on the distance driven with maybe the vehicle's weight considered as well. An OBD dongle was used to transmit distance driven data via a cellular data connection to the DMV. The dongle set off the burglar alarm on our 2014 i3 sometime during the night. To prevent this, the value of the following coding parameter in the Roof Function Center (FZD) could be set to inactive:

OBD socket alarm (BimmerCode expert mode)
3002->OBD-Alarm: active (default)

However, setting this parameter to inactive is considered to increase the risk of an unknown OBD dongle being installed in one's i3. Maybe that change had been made to your i3 when the GPS tracker was installed.

I think that also means a new key can be coded on the steering column with suitable software/hardware via theOBD. Hence why it alarms if it detects current drain on the OBD port whilst armed. Was an issue in UK some time back with cloning kits. Required access to car via some other means usually blocking the locking request from the fob.

 

[Gonville]

Now that you mention it, I was getting spurious alarms, but perhaps that was related to super hot summer days. I have only tried BimmerLink so far but will try BimmerCode at some point in the next few months. In any case, no dongle installed now.

Either a wasp or current drain on OBD for sure.

 

[mfogarty]

Another vote for the Veepeak adapter. Has worked fine with Bimmercode, Bimmerlink and the Electrified app.

 

[jfk68]

I'm coming back from a journey that I knew would be dangerous: 150 km on the highway with my i3 120Ah. 20 km from home: loss of power... I exit the highway and finally end up 500m from home with no power and 13% remaining. Here are the data at this moment.

 

[jfk68]

… Finally a neighbor was able to pull an extension cord and I charged for 20 minutes / 0,5kWh. I was able to leave and strangely with no loss of power for the last 500 meters. The data at this moment:

 

[Mondomensch]

It looks like you had a relatively large difference between minimum and maximum cell voltage in the first readout, with the minimum improving a fair bit after your short extension cord charging.

Could it be that the car wouldn't drive because the lowest-voltage (emptiest) cell was too low and the system wanted to prevent battery damage?

Seems like your pack could use some cell balancing; I'll leave it to the more expert here to make suggestions on how best to accomplish that.

 

[alohart]

It looks like you had a relatively large difference between minimum and maximum cell voltage in the first readout, with the minimum improving a fair bit after your short extension cord charging.

Could it be that the car wouldn't drive because the lowest-voltage (emptiest) cell was too low and the system wanted to prevent battery damage?

Seems like your pack could use some cell balancing; I'll leave it to the more expert here to make suggestions on how best to accomplish that.

I agree with your analysis. This seems to be more evidence that the BMS doesn't calibrate very well for a decreasing usable capacity. Maybe @jfk68 rarely drives to very low charge levels, so the BMS has not had an opportunity to calibrate.

@jfk68, do you typically charge to less than 80%?

It would be interesting to learn the minimum and maximum cell voltage difference when the battery pack's charge level is 100% which is where top-balancing tries to minimize the voltage difference. If a 0.1V difference remains, or even a difference greater than 0.01V, cell charge level balancing should be attempted. Unfortunately, there's nothing that an i3 owner can do to accelerate this process other than to charge to 100% and allow the car to rest at a high charge level as long as possible. Although cell charge level balancing apparently occurs at charge levels less than 100%, it probably occurs most rapidly at 100% because the balancing current would higher at higher voltages. If you drive daily, maybe charge it to 100% at the end of each day before parking it overnight.

 

[jfk68]

@jfk68, do you typically charge to less than 80%?

Yes I always charge under 50% but the charge ends generally 2-3 hours before I take the car. I will try to let the car sleeping with 100% overnight more often...

 

[Zwerius]

I've received my Vgate icar pro wifi today and tried to use it with the mi3 app. Connected it with the wifi of my iphone.
The data is shown correctly. Nice. SoH from battery was 98% (after 110.000 km). That was what I was looking for.

But a few seconds after leaving and locking the car, the alarm of the car started making a horrible noise. I never heard the alarm before, so it's probably normal alarm sound.

So, can I not just leave the OBD in the car and do I have to remove it during regular use of the car? Is it only ment for testing now and then? Or is there a setting somewhere to be changed?

 

[mojo]

As I understand it, that is an intentional feature of the alarm system - IIRC referred to in the Owner's Manual somewhere?

I believe you can change the coding of the car so that the alarm is not triggered by activity on the OBD port while the car is locked, but I can recall a suggestion that leaving an OBD device plugged in can prevent a complete shutdown into power saving mode when the car in unused. That probably depends on the exact type of OBD device used.

 

[alohart]

So, can I not just leave the OBD in the car and do I have to remove it during regular use of the car? Is it only ment for testing now and then? Or is there a setting somewhere to be changed?

It's only meant for testing now and then. Leaving an OBD dongle plugged in could make an i3 less secure and might result in increased energy consumption because the 12V pin of the OBD port never powers down like 12V accessories do after several minutes.

When I was part of a pilot program to evaluate using distance driven as a factor for determining the annual registration fee, the program supplied an OBD dongle with a cellular radio that reported odometer readings periodically. This triggered our i3's alarm after shutting off our i3, usually not immediately, though. I was able to disable this alarming behavior by changing a FZD (Roof Function Center) parameter value using BimmerCode in expert mode:

3002->OBD-Alarm: set to inactive

However, I decided that doing so wasn't worth the risk, so I changed the parameter's value back to the default "active".

 

[Zwerius]

My i3 has 110,000 km. The SoH according to the OBD dongle is 98%

 

[havrla]

BMW Max Kappa



Max Kappa (short for “Kapazität”) is the BMS estimated snapshot capacity at that point in time, its based on external factors (temperature, current load), coulomb count, these factors are then fed into a statistical model to provide an educated guess of what the current capacity of the pack. This is what is shown in the service menu. It is not like a fuel tank you can't just measure it as there is chemistry involved.



Max Kappa as such is not a measure of anything, it is a guess of what the BMS thinks the pack is doing at that moment in time and therefore how many kWhs are available. It is not a true reflection of capacity.



Consider the following scenario, it has been cold overnight you haven't preconditioned so the battery is at 4c well below its preferred operating temperature of 24-28c, Max Kappa will show a corresponding low number as due to the cold the pack is less chemically active, as you drive the load starts to warm the pack up, so you then lose range but Max Kappa goes up due to battery reaching operating temperature.



The only way to test true capacity and health of a battery is to charge and discharge the pack to known points and record the input and output rates. It is perfectly possible for Max Kappa to read 19.1kWh (on a 60aH) on a full charge but the battery actual be degraded, or vice versa for it to read well under 15kWh but be perfectly fine.







Orange Machine. Battery safety tester (including pressure). Discharge charge full cycle.

The orange box does not perform a capacity test, but a mandatory safety test before inserting the battery into the vehicle.

 

[havrla]

My i3 has 110,000 km. The SoH according to the OBD dongle is 98%

bla bla bla lala ba ba ba bla.
Either someone modified the BMS adaptation, for example reinit even the 60Ah version, or there is a mistake somewhere. 110,000 km has a degradation of 11 - 22% depending on the battery version.

 

[mfogarty]

bla bla bla lala ba ba ba bla.
Either someone modified the BMS adaptation, for example reinit even the 60Ah version, or there is a mistake somewhere. 110,000 km has a degradation of 11 - 22% depending on the battery version.

I had my 2020 120Ah tested at an EV specialist garage when I got it with 109k and the SoH is 96%. Well above your figure of 11%. Can you show your source for these degradation figures?

 

[alohart]

I had my 2020 120Ah tested at an EV specialist garage when I got it with 109k and the SoH is 96%. Well above your figure of 11%. Can you show your source for these degradation figures?

Li ion battery cell degradation is a certainty even when cells are just being stored. It occurs with every charge-discharge cycle due to irreversible electrochemical side reactions that can't be avoided. These side reactions can be minimized which the BMS is designed to do.

The BMS in the 120 Ah battery pack in our former 2019 i3 reported the cells' average usable capacity to be ~125 Ah after 32k miles, so the SoH exceeded 100%! That's not possible. However, because the initial capacities of the cells were higher than the spec, degradation was hidden initially but will be exposed after the cell capacities decrease below 120 Ah. Something similar probably explains why the SoH of your battery back is reported to be so high after a significant distance driven and 4 years of aging.

Another explanation would be that SoH is merely a calculated estimate relative to the nominal new capacity, not the actual new capacity. It is not a value that can be measured directly by the BMS, so there is always some imprecision in the SoH estimate. Repeated displays of the SoH can show different values, both greater and lower, due to the imprecision in the calculated estimates, the differences in temperature, the differences in the recent charge and/or discharge rate, etc. However, 94 Ah and 120 Ah battery cells seem to be much less likely to degrade rapidly compared with 60 Ah battery cells.