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.

Dip switches stay as they come. US3000C can have up to 16 in 1 battery group. Just follow the below grouping for the link cables. Standard LAN cable works where you need a longer length than those supplied with the battery. Page 5 from the US3000C manual below.

I would however increase your number of positive and negative battery cables and use a suitably rated busbar. You currently have a single cable rated at 100A constant with a 120A peak for 8 batteries with a charge/discharge current limit of 296A. Splitting them as you mentioned earlier with the additional batteries into 4 stacks of 4 will still result in a charge/discharge current per stack of 4 batteries of 148A. If you could ever hit that limit would be based on your inverter etc. With my setup I can currently push 150A at 6 batteries so I have multiple negative and positive cables to accommodate it.

The battery SOC% will be out of sync between the older (US3000) and newer (US3000C) batteries because the capacity (Ah) of the older batteries has reduced over time from 74Ah compared to the newer. Be careful with the firmware updates as there are different firmware files for each different version. The US3000 batteries shipped initially with firmware version 1.3. The latest firmware is 3.4. Depending on when the US3000C shipped they have one of two different chip sets and different firmware versions as a result. If the board version is NF4.E2 (serial numbers that have this format HyymmddC3nnnnnnn) they could be running version 1.8 of the firmware depending on the date. There are later versions of the firmware for this board. I have seen 2.1 and 2.2. I have 2 US3000C and 4 US3000 that visibly (number of green SOC lights flashing) and viewed with Battery View at different times can be quite different. They all reach 100% SOC during the day. They also discharge differently as well with the US3000C discharging deeper. As example the 2 US3000C can have 2 solid green SOC lights and the 3rd one flashing while the 4 US3000 will have 3 solid green SOC lights and the 4th one flashing. It also happens that once the average SOC gets closer to 100% the 4 US3000 become IDLE (SOC 100%) when viewed in Battery View while the 2 US3000C will still be taking quite a high charge current. The BMS controls the advised charge current of each battery so there is never an over charge issue. This is one of the advantages of Pylontech and the reason it is possible to mix and match the different capacities and ages.

2 issues 75/15 MPPT doesn't support 48V Communication is via VE.Direct only so it requires a GX Device Datasheet-BlueSolar-and-SmartSolar-charge-controller-overview-EN.pdf (victronenergy.com)

Only toggled the country to United States. Had to do it with all the different versions of Battery View to use it successfully.

Had a similar issue and I just set the country region to United States.

My neighbour had exactly the same issue with 4 CFE-5100S connected to a 8kw Deye. Leon from CFE came out to his house and updated the firmware on all 4 batteries. He also switched him over to the new Smart Energy Plat app. Have a look at this thread -> CFE - 5100s Batteries - The Final Showdown! Warning, it's not pretty! - Batteries - Power Forum - Renewable Energy Discussion. Leon left his local WhatsApp number. Inverter firmware was also updated at the time. I haven't heard him complaining again about the issue.

Both the US2000 and US3000 are RJ11. US3000C is RJ45.

I have used both kits (HD cabling and Communica) on US3000 and US3000C. US3000 has the RJ11 console while US3000C has the RJ45

You don't need 2 kits. The kit is complete. It has both RJ11 and RJ45 ends. It is much cheaper than the alternative from HD cabling Pylontech Battery Monitoring Cable For US2000, US3000a/b, US3000c, UP2500, UP5000 | Pylontech Console Cable (hdcabling.co.za)