JKKM

Yes all Victron equipment.

I can't comment on what the fixes are but can confirm that 1.7 -> 2.1 months back and then to 2.4 recently, 2.1 -> 2.4 and 2.2 -> 2.4 firmware updates were all applied successfully. No issues experienced to date.

I have tried both Segen and Pylontech and each time was given v2.1 even though I specifically asked for v2.2 as I could see my newest US3000C has v2.2.

You can get a zip file with versions for the old (2.8) and new (2.1) chip here -> Lithium storage unit Pylontech US2000C/3000C | Effekta | EFFEKTA Regeltechnik GmbH. I have seen V2.2 for the new chip US3000C Pylontech's but haven't been able to source it.

US3000C supports 90% DOD while the US3000 only 80% DOD.

Comfortably ran 4 x US3000 on a single set of 2M long Pylontech cables for over 3 years with my Victron Quattro 48/8000. Only started to double up cables when adding the 5th and 6th which are US3000C. No issues with compatibility between US3000C and US3000. The US3000 were updated to v3.4 of the firmware prior to introducing the US3000C as the new master. It's best to ensure the SOC is approximately the same when introducing additional batteries.

Pylontech contacted Segen Solar who then supplied me with the software and the firmware file as well as the how to document.

Yes

I've seen this on the US3000 running firmware v1.3. It doesn't happen with firmware v3.4

Information from the battery that was exhibiting the behavior. The new battery which does not have the issue.

Had a similar issue with the sudden increase in "Ambient Temperature" above 90% SOC compared to the rest of my batteries. Firmware update didn't fix the issue. Subsequent BMS replacement also had no effect. Pylontech then replaced the battery.

I suspect you might have an issue with the console cable. I had a similar situation and found that the cable was no longer working correctly. Check the windows device manager prior to plugging the cable in and then check it again after plugging it in to ensure you see both a COM port and a Universal Serial Bus controller.

My cycle counts are a little further apart. Oldest US3000 has more than 1000 cycles and newest US3000C less than 30.

There are no issues adding a new battery. The new battery must be the master battery as described in the Pylontech manual along with how to add it.

You will require this cable RS232 to USB Converter Cable Kit for Pylontech | SegenSolar. It has both connectors for the different console ports i.e. RJ11 for US3000A and RJ45 for US3000C. I have found that Battery View will also require you to set your computers REGION setting to United States.