Is it normal that for the battery received with the 'FPV Combo' I had to do a firmware update, while for the 4 batteries received later with the 'Fly More' I did not have to do anything?
Thx

Hi there. Thank you for reaching out. You may plug in the said batteries one by one in the aircraft and run the DJI Assistant 2 software and check if there is an available update. Please don't hesitate to reach us if you have other inquiries. Thank you for your valued support.

I've had better luck updating battery firmware using the DJI Assistant 2 vice using the Fly App.  

But then could a sudden battery 'black-out' happen if the firmware is not synchronized?
The batteries are working perfectly for now...

You need to update all batteries if the FW update has a battery fix. Run the update multiple times one for each battery. And as said above use the Assistant 2.

bjr981s Posted at 5-29 08:56
You need to update all batteries if the FW update has a battery fix. Run the update multiple times one for each battery. And as said above use the Assistant 2.

Something is not clear, is there really an update on the batteries or is it just a generic check to verify the correct performance? If it was so important to update the battery firmware, the warning should appear for all new batteries and not just the first one, am I wrong?

FlyLow Posted at 5-29 09:32
Something is not clear, is there really an update on the batteries or is it just a generic check to verify the correct performance? If it was so important to update the battery firmware, the warning should appear for all new batteries and not just the first one, am I wrong?

Yes, you are wrong. Sorry.

The first time you do a FW update it updates all functional parts of the drone. Gimbal, sensors etc. including the battery. As the batteries can be swapped it cant update other batteries as they are not in the drone. So you need to swap the battery and perform the update again.

Use DJI Assistant 2. Do the first FW update. The replace the battery. Start assistant again and it will advise of a FW incompatibility issue and it will ask you to start the update. It will be very quick as it is only updating the FW on the battery.

Sometimes a FW update does not update battery FW. If this is the case once you change the battery it will not advise that an update is required so you can ignore subsequent batteries,

If you don't use assistant you will need to replace the battery and go into the system settings and do a manual check of FW it will advise of any incompatibilities.