Project OBD2 - Mobile App v1.2.1 and later

[JohnG]

Have the very latest BSM car was delivered back after 2 weeks with approx. 21mv imbalance. Charged again to 100% over the weekend, car showed 100% SOC and app showed 92.8%. Cell Voltage Max = 4.176V Min = 4.157V. Battery Voltage in car 449V app 450.25V. Balanced for 2.5 hours, charger showed 0.3kW draw. SOC in app increased by nearly 1% to 93.6% Cell Max Volt = 4.172 Min Volt 4.151 Voltage in App 450 while car displayed 449. I have the battery warmer option, but after leaving the car in drive and not actually driving, I saw no increase in the battery temperature, which was showing +2C. Unsure if the battery has to be much colder before heating is carried out even if the option is set to On? Before the BMS update balancing drew around 2.2kW now it's around 1kW the max SOC I have seen in the app after balancing for 4 hours was 93.8% Regarding issues with the Thai app. I was unable to get it to work with a Galaxy A51 5G running Android v10, but have no problems with a Samsung S8 running Android v or a MotoG6 Plus running Android v8

 

[JodyS21]

On the June/July BMS and it feels like it's close to 8 or 9 hours hours, often I just stop it short as need to go out.
That's with 13mV inbalance.

I do it about once a month. Three times since I had the car 2 months ago.
Will doing it more often make it considerably less?

I just created this post, thought it may help

Battery Cell Imbalance - difference

I thought I'd do a bit of a poll, as it's asked a fair bit. What is an ok cell imbalance amount - and balance time needed. You would only be able to know the actual Min & Max cell voltage, if you have the OBD2 gadget & app, or OVMS. E.g. Max cell voltage 4.168 / Min cell voltage 4.151 (total...

www.mgevs.com

 

[JodyS21]

Have the very latest BSM car was delivered back after 2 weeks with approx. 21mv imbalance. Charged again to 100% over the weekend, car showed 100% SOC and app showed 92.8%. Cell Voltage Max = 4.176V Min = 4.157V. Battery Voltage in car 449V app 450.25V. Balanced for 2.5 hours, charger showed 0.3kW draw. SOC in app increased by nearly 1% to 93.6% Cell Max Volt = 4.172 Min Volt 4.151 Voltage in App 450 while car displayed 449. I have the battery warmer option, but after leaving the car in drive and not actually driving, I saw no increase in the battery temperature, which was showing +2C. Unsure if the battery has to be much colder before heating is carried out even if the option is set to On? Before the BMS update balancing drew around 2.2kW now it's around 1kW the max SOC I have seen in the app after balancing for 4 hours was 93.8% Regarding issues with the Thai app. I was unable to get it to work with a Galaxy A51 5G running Android v10, but have no problems with a Samsung S8 running Android v or a MotoG6 Plus running Android v8

Some good data there. Let's dig into it!

Having watched (videod the run flat test) the dash in the car with the app next to it. The car dash Volts always rounds down (ignores the decimal place). The voltage very often fluctuates 0.25v in the app with refresh rate etc.

I'm pretty sure the actual charge stops once the first cell hits something like 4.17volts, that's how they've programmed it.
So you had 19mv imbalance once charged.

The balanced cell data is weird, you ended up with a bigger imbalance - 21mv!?!?!

Actually the SoC% doesn't seem to make sense either.
You ended up with a lower total voltage (450 vs 450.25) and lower max cell voltage (4.172 vs 4.176), that should not therefore show a higher SoC (93.6 vs 92.8).


I wonder if you cannot accurately read the figures whilst it's doing it's stuff (charging/balancing) and that is why it doesn't seem to tally...
What would be ideal, I thought about this before, but it's not possible. Would be to stop once charged and let settle for 5mins / take readings, then put on balance, then once balanced do the same again.

 

[JodyS21]

This is a very interesting read.

EV Battery Health: What 6,000 EV Batteries Tell Us | Geotab

How long does a typical EV battery last and is there a measurable difference between make and model? Learn how to prolong your EV battery life here.

www.geotab.com

Here's a nice diagram from it:

State of charge (SOC) and the buffer effect​

Another anticipated reason for the differences in battery health between manufacturers is how SOC is controlled. Operating a battery at near full or empty has implications on battery health. To limit this effect, many manufacturers add a buffer, effectively preventing access to the extreme ends of the SOC window (shown in the image below).

In addition to the protection buffers at the top end and bottom end of the battery range, many vehicles provide the EV owner the option to stop normal daily charging at a level below 100%.

Figure 3: Battery protection buffers control the usable state of charge window for an EV.

 

[JohnG]

Some good data there. Let's dig into it!

Having watched (videod the run flat test) the dash in the car with the app next to it. The car dash Volts always rounds down (ignores the decimal place). The voltage very often fluctuates 0.25v in the app with refresh rate etc.

I'm pretty sure the actual charge stops once the first cell hits something like 4.17volts, that's how they've programmed it.
So you had 19mv imbalance once charged.

The balanced cell data is weird, you ended up with a bigger imbalance - 21mv!?!?!

Actually the SoC% doesn't seem to make sense either.
You ended up with a lower total voltage (450 vs 450.25) and lower max cell voltage (4.172 vs 4.176), that should not therefore show a higher SoC (93.6 vs 92.8).


I wonder if you cannot accurately read the figures whilst it's doing it's stuff (charging/balancing) and that is why it doesn't seem to tally...
What would be ideal, I thought about this before, but it's not possible. Would be to stop once charged and let settle for 5mins / take readings, then put on balance, then once balanced do the same again.

I will try the "Pause" idea when I next do a 100% charge. I will unplug and then start a new charge session once the car reports 100% SOC. Will then let it balance for as long as I can and see what the charger reports has been pulled for the time it was balancing and then post some more numbers. Agree a bit weird that when I stopped the balance the inbalance we greater than when the car said it was fully charged.

 

[JodyS21]

I will try the "Pause" idea when I next do a 100% charge. I will unplug and then start a new charge session once the car reports 100% SOC. Will then let it balance for as long as I can and see what the charger reports has been pulled for the time it was balancing and then post some more numbers. Agree a bit weird that when I stopped the balance the inbalance we greater than when the car said it was fully charged.

I missed stopping mine this evening before it did the balance

Unless I'm mistaken, it won't start the balance again will it, if you stop it once fully charged and then plug it back in?
(Isn't that why the problem cars trying to rebalance have to run down a bit before putting it back on charge to balance again?)

 

[Septian]

I missed stopping mine this evening before it did the balance

Unless I'm mistaken, it won't start the balance again will it, if you stop it once fully charged and then plug it back in?
(Isn't that why the problem cars trying to rebalance have to run down a bit before putting it back on charge to balance again?)

Yeah, I'm pretty sure that's the case, I tried this on mine a while ago, it was balancing at the time, but when I plugged it back it, it didn't resume balancing.

 

[rbpasapera]

Just plugged mine in to confirm that obd2 Bluetooth and Thai app are working fine, next week I will be posting data after full charge and balance.

 

[MG ZS EV WEST YORKSHIRE]

Just plugged mine in to confirm that obd2 Bluetooth and Thai app are working fine, next week I will be posting data after full charge and balance.

View attachment 2344

View attachment 2345

If you have the new mid - Jan BMS firmware, the battery management lowers the SoC from 97% to 93% and on Depth of Discharge from 5% to 0.5%. I fully charged my car earlier this week including a 4 hours balance as well and whilst the car was showing 100% on the graticules (dashboard) the app only showed 93.4% due to the 3.5% top and 3.5% bottom buffers.

 

[JodyS21]

@aleks57 I've added your data to the spreadsheet.
@rbpasapera Added the data from your first screen print to the spreadsheet.

All UK folk have an EPS version of ZsrdV084Rs.
All non UK cars seem to have EPS version Zs11ESVf17.

@rbpasapera welcome to the unique club, you are the only person who has a different FVCM or FDR version!
Everyone else has; FVCM: Z5.0RC07 & FDR: ACC_SW:5.0
You have; FVCM: M2.0RC02 & FDR: ACC_SW:2.0

ECU Module version spreadsheet

I'll update this top post as more data is provided. In an attempt to figure out what the different versions of all the software do/cause, we are putting together a list of peoples car ecu versions. If you have the OBD2 device (currently being looked at in another post) or OVMS, please post your...

www.mgevs.com

 

[Davidjones75]

Just joined this group some great information , one question I have the app and works ok most of the time but have noticed whilst driving the SOC seems to jump rather than smoothly decline .watching it yesterday it jumped from 48% to 44% then to 39% , could it be my obd Bluetooth device disconnecting the reconnecting ? It is an old konnwei.

 

[AbuG]

Just joined this group some great information , one question I have the app and works ok most of the time but have noticed whilst driving the SOC seems to jump rather than smoothly decline .watching it yesterday it jumped from 48% to 44% then to 39% , could it be my obd Bluetooth device disconnecting the reconnecting ? It is an old konnwei.

It's smooth on mine, likely your device is the issue.

 

[Davidjones75]

It's smooth on mine, likely your device is the issue.

Thanks waiting for a new one from AliExpress.

 

[Mgmedd]

OK so now I have charged and balanced and here are the screenshots for my car at 100% SoC according to the screen in the car. This car has an old (pre BMS issue and pre 450V adjustment) BMS software (1125600R15)) Perhaps something wrong with the app being used to calculate SoC or this indicates that there was an upper buffer prior to the update. Not sure

 

[AbuG]

OK so now I have charged and balanced and here are the screenshots for my car at 100% SoC according to the screen in the car. This car has an old (pre BMS issue and pre 450V adjustment) BMS software (1125600R15)) Perhaps something wrong with the app being used to calculate SoC or this indicates that there was an upper buffer prior to the update. Not sure

SoC at 96.1% is reasonable, (I get 97%). The rest is the upper buffer and degradation
There's a 35mV imbalance... Could be better, I think. How often do you do an equalisation charge?

 

[Mgmedd]

I thought is was doing them most evenings that I charge but am now not sure that's the case as I use a smart charger that sets the charing times. Hence it may switch off once the primary charge is done but before the equalisation charge has had time to complete. I will check this over the next few weeks.

 

[JodyS21]

I thought is was doing them most evenings that I charge but am now not sure that's the case as I use a smart charger that sets the charing times. Hence it may switch off once the primary charge is done but before the equalisation charge has had time to complete. I will check this over the next few weeks.

Do you get graphs of the power usage from your smart charger, if so folk normally can see when it switches from charging to balancing and then when it drops to zero so the balance has finished.
I'd also guess that it may not quite be finishing the balance given 35mV difference, nothing to worry about though!

I had it down in the spreadsheet that you had 99.78% SOH - has yours really gone down since then to 99.71? How many miles you done since then?

The car dashboard shows the percentage of what it allows to be used.
The App SOC shows the real percentage of what the full battery is.

 

[JodyS21]

I've created a graphic to try to explain how the battery usage would appear to be on the car.
Hope this helps explain the Cars Dashboard charge % and the Apps SoC%.
This is based on data from myself and AbuG running our cars from max charge to completely flat.

I've added it to the first post in here too ECU Module version spreadsheet

 

[rbpasapera]

I've created a graphic to try to explain how the battery usage would appear to be on the car.
Hope this helps explain the Cars Dashboard charge % and the Apps SoC%.
This is based on data from myself and AbuG running our cars from max charge to completely flat.
View attachment 2383
I've added it to the first post in here too ECU Module version spreadsheet

This graphic would be based on data with 100% SOH, could it change with a different SOH?

 

[JodyS21]

This graphic would be based on data with 100% SOH, could it change with a different SOH?

Yes that is indeed assuming 100% SOH.
It is beyond my (current!) knowledge how it changes with regard to SoH.

There's not many cars out there that haven't got 100% SoH to collect data from. Probably would need historic data as the SoH changes to try to figure out how it works...