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Is there still a community of Zero Gen2 users who continue to download their logs directly from the MBB or BMS using a TTL cable or other equipment? I used to do this with a TTL cable, but I can no longer do it on my 2023 model year Zero S. I don’t know if this is due to a change in my computer and the TTL cable driver, or a change in the bike’s firmware. When I bought my bike, the MBB/BMS firmware versions were 37/44. After the dealer's update in April 2024, I was on 39/46. Since the dealer's update in April 2025, I’ve been on 41/48.

I'm also unable to check the firmware on my 2023 model year Zero S using the Zero Next Gen v2.13.0 (1) app on Android. The app detects that the firmware is Rev 41 for the MBB and Rev 48 for the BMS, but fails to find any update. Is your app able to make firmware updates?

I suspect that in the recent firmware updates installed by the dealer during service visits, Zero has made changes that have altered quite a few things.
In fact, if you compare the user's manuals for the motorcycle from 2023 and 2026, you can see that there have been changes. For example, regarding long-term storage, in 2023 you had to charge it to 60% and unplug the bike, but in 2026 the manual states that you should leave it plugged in and that after 30 days it will automatically discharge to 80% SOC! If that’s true, it shows that Zero has completely changed certain things... I can’t tell you if my 2023 S has switched to this new operating mode, since this winter I did as usual, leaving it charged at around 50%, and the SOC didn’t change during the storage period. If you want to check the manual’s instructions:
Zero S-DS-DSR 2023 Owner’s Manual 88-09956-01, see page 6.27
Zero S-DS-DSR 2023 Owner’s Manual 88-09956-06, see page 6.27

In your responses, and to help us identify the issue, please provide your motorcycle model, your MBB and BMS firmware numbers, whether you have encountered any difficulties extracting logs from the MBB or BMS port, and what device you are using to extract these logs.

You reminded me I ought to try mine with one pack at a time to see what happens.

Yes, and I also planned to do the same. Nice days are coming. I will try to do it soon!

Yes, there is some info inside the logs that can inform you about the battery capacity and health.
Look at there: https://www.electricmotorcycleforum.com/boards/index.php?topic=11638.msg116919#msg116919
I have a spreadsheet where I summarize some capacities calculations. I have added some data extracted from your log. It seems that your pack is in much better health than mine (which is from 2023 whereas yours is from 2021). I attach the spreadsheet.

From the log, it seems that when you leave your bike resting, the SOC decreases. Is it the case ? I have 2 Zero (FXS 2016 and S 2023), and when I leave them in the garage (even for a long time) their SOC does not vary at all. 
It also seems that when your bike is resting, the SOC periodically adjusts for voltage. That do not happen with mine...

And also, your log has some problems. The lines are not in chronological order, and there are some inconsistencies. It would be better to share the bin files (MBB and BMS). If your bike has not been used for a long time, perhaps it would be good to use it a little bit. It will push away the old log lines and replace them by fresh ones!
 

If you want to analyze in detail your batteries, ZeroSpy (Android application) can be helpful. It records the parameters of your bike every second. And you can further make graphs in order to analyze the records.
Here is an example with my FXS 2016 (with two 3.3 kWh amovible packs).
https://www.dropbox.com/scl/fi/2qwb24m5nykw2qvnrjkwx/ZeroSpy_modele_analyse.des.donnees.xlsx?rlkey=8or6htwb51w8mqc51jzuq7glo&dl=0
I make a correlation between the balance and the battery current.
You can compare your data to mine.

Another possibility is a change in the firmware way to estimate the SOC.
Here is some of my experience with my FXS 2016.

My old firmware was mainly calculating the SOC from the estimated capacity of the pack in Ah, and the Coulomb counting in Ah. That made the SOC monotonously decreasing, and accurate. Nice !
Indeed, all the logs with this firmware contained lines like
- "Switching to voltage SOC mode"
- "Switching to coulomb couning SOC mode" (there was a typo in the logs: it was written couning instead of counting)

And I am pretty sure also that the new firmware that has been installed is mainly calculating the SOC from the pack voltage, that is greatly oscillating depending on the way you use the bike.
And since this new firmware was installed, there is no line in the logs saying that the SOC mode is using Coulomb counting.

That is why the first thing is to answer if the change in SOC behaviour is correlated with a firmware change or not.
Of course, if the firmware has not been changed, the problem probably comes from the battery.

But it is still not certain. I have also experienced a fundamental change in my bike behavior due to the fact that the MBB had lost all its settings. The most visible consequence was a jump in the odometer (it increased by 3000 kms in one night), and completely wrong odometer count, wrong speeds (all that came from a lost transmission ratio), and also some less visible parameters were lost (pack capacity, VIN number,...). Of course, in that case, the SOC calculation became quite confused also...
Zero reprogrammed the bike and after that it worked fine.

The conclusion is that you should be attentive to anything else that could have changed in the bike (in my case: firmware, and MBB losing its settings).

@dee91
Do you plan to get the "CAN" or the "Enable" version ?
You could be interested by my own experience related here: https://bit.ly/Zero_charger

I agree with Curt. And if you want to take precautions, you can bypass the fuse with another 10A fuse.