Battery State of Health Discussion

[Phximiev]

Just bought the OBDlink MX+ and installed Car Scanner on my iPhone. At first blush it seems to work quite well. Its "All Sensors" option displays a lot of data including all of the traction battery cell data. I also compared it against Canion. While it doesn't have the same display of cell data that Canion does, it does give the same information.

Ah: 19.9 :roll:

High cell: 4.08
Low cell: 4.07.

 

[MickeyS70]

Ah: 19.9 :roll:

This would mean < 50% of SOH, could be due to age, mileage or environmental factors but maybe the BMU’s default degradation algorithm was never corrected. A quick way to find out is to run ODBZERO’s (Android) CAP2 calculation to see if it’s value differs significantly from the 19.9Ah.
Mickey

 

[Phximiev]

We have 63k+ miles on our iMiev and its been in the heat for the 9 years or so we've owned it. I just turned the car on to do a Car Scanner review for JoeS and it shows 45 miles of range, which is optimistic.

I have wondered about the Ah values. OBDZero is on the Android app store? I use an old Galaxy 3 7 tablet to run Canion. I assume that I can download it and run it on this old tablet? I did try to get into the Play store and was frustrated by the password issues. Its been years since this Mac user has used this tablet.

As mentioned above Car Scanner and Canion give the same values.

 

[MickeyS70]

I have wondered about the Ah values. OBDZero is on the Android app store? I use an old Galaxy 3 7 tablet to run Canion. I assume that I can download it and run it on this old tablet? I did try to get into the Play store and was frustrated by the password issues. Its been years since this Mac user has used this tablet.

As mentioned above Car Scanner and Canion give the same values.

Yes, it’s available on the the Google Play store, I run it on a old Galaxy Note Phone.

The value that Car Scanner and CanIOn display is what the BMU ‘thinks’ the remaining capacity is.

Heat certainly has a negative effect, therefore the 19Ah could be accurate especially if ye did the battery calibration regularly (discharge below 2 bars and charge fully with granny charger)

ODBZero CAP2 re-calculates and displays the current capacity by using more or less the same procedure but it cannot update the BMU, you need other tools to correct it in one go (MUT/Diagbox/HobDrive etc) or keep doing the ‘native’ procedure over and over until the value stops changing..
Mickey

 

[Phximiev]

I did find OBDZero and Hobdrive on the Google play store, but couldn't get them to download. I selected install, agreed to the permissions, then the Galaxy Tab 3 would lock up.

:evil:

I have driven the car below two bars and reset the capacity many times. I'll try it again when I get a chance.

 

[Phximiev]

After reset (charge to full after driven below 2 bars) summary values from Car Scanner Pro are the same:

Ah: 19.9 :roll:

High cell: 4.08
Low cell: 4.07.

I'll do a few more over the next week or so and see what happens.

 

[MickeyS70]

Mine only reaches 100% SOC if the highest cell voltages is around 4.1V, i.e yours doesn’t seem to charge fully and therefore won’t calculate a new SOH. Make sure you use a level 1 EVSE and leave the car for an hour after charging has finished.

See below for a more detailed description of the process

https://myimiev.com/forum/viewtopic.php?t=2386&start=80

Mickey

 

[Phximiev]

Mine only reaches 100% SOC if the highest cell voltages is around 4.1V, i.e yours doesn’t seem to charge fully and therefore won’t calculate a new SOH. Make sure you use a level 1 EVSE and leave the car for an hour after charging has finished.

Thanks. We're using the standard Mitsubishi iMiev EVSE (which came with the car) that plugs into a 120v outlet. On the last measurement the car fully charged overnight and thereafter in the late morning I took the measurements.

I don't know what to do about not charging fully to 4.1v. Any suggestions?

 

[MickeyS70]

I don't know what to do about not charging fully to 4.1v. Any suggestions?

Not sure, best to verify what SOC has been reached after a full night’s charge. If it doesn’t show 100% on the app then there is an issue either during charge (possibly high impedance cell) or after (something draining the battery just ever so slightly)

 

[CZeroOwner]

I don't know what to do about not charging fully to 4.1v. Any suggestions?

Hi Phximiev

The cell voltage reaches 4.1 volts toward the end of the charging process but decreases quickly to 4.09 volts after charging stops. An hour after charging stops 4.08 volts is normal.

If the BMU reported capacity is in error and the true capacity is much more than 19.9 say 30 Ah. Then reducing the SoC to two bars is not enough to trigger a full capacity measurement. The BMU computes the SoC buy subtracting the the used Ah from its estimate of the of the capacity. 2 bars equals about SoC 20% which under normal circumstances should trigger a full capacity measurement. However 80% of 19.9 is 15.9 Ah. When the meter shows 2 bars you have only used 15.9 Ah. If the true capacity is 30 Ah then there is still 14.1 Ah left in the battery.

Now here is the interesting detail. The true trigger for the full capacity measurement is not 2 bars or a SoC of 20% but a battery voltage of 339 volts. If there is still 14.1 Ah in the battery then the voltage will be greater than 339 volts. The battery voltage must be below 339 volts before charging starts in order to perform a capacity measurement.

There are three way to solve this problem.
1) The quickest way is to find a Mitsubishi dealer that has the equipment and knowhow to measure and reset the battery capacity. Ask if the person doing the work has be trained by Mitsubishi. This costs maybe $200.

2) Download and install Hobdrive as Mickey suggested. If your Tab 3 doesn't work find a device that does. Hobdrive can reset the battery capacity.

3) Download and install OBDZero. If your Tab 3 doesn't work find a device that does. Then perform a cap1 or better yet a cap2 measurement and report back the results. OBDZero cannot reset the battery capacity but it will give you an estimate of the true capacity of the battery.

You can download the user manual for OBDZero here: https://obdzero.dk/wp-content/uploads/2022/08/OBDZeroUserManual38.pdf

Good luck
David

 

[JoeS]

Opened up this new thread and moved the above posts in here from the App thread -

https://myimiev.com/threads/smartphone-tablet-apps-for-i-miev-c-zero-and-ion.4936/#post-43753
Incidentally, added a number of Car Scanner screenshot on that thread, courtesy of Phximiev.