February 2, 20242 yr Hi experts I have a bank of 8 Pylontech US3000s and US3000Cs connected to 2 Mecer 5.5kw inverters. These are connected to 24 PVs of 330W in 8 strings of 3. I'm running the SMH Solar Management Hub. Everything has worked well for a couple of years now. However my batteries seem to charge much slower than usual in the last few weeks. On a full day of sun I'm battling to charge more than 40-50% I noticed something strange today: The 3 Pylontech US3000C's were at SOC 56% and the 5 Pylontech US3000's were at 76%. The system is showing 68% overall SOC. Does anyone know why this would happen and how to correct it? Many thanks! Deon
February 2, 20242 yr 2 hours ago, Deonbayly said: Hi experts I have a bank of 8 Pylontech US3000s and US3000Cs connected to 2 Mecer 5.5kw inverters. These are connected to 24 PVs of 330W in 8 strings of 3. I'm running the SMH Solar Management Hub. Everything has worked well for a couple of years now. However my batteries seem to charge much slower than usual in the last few weeks. On a full day of sun I'm battling to charge more than 40-50% I noticed something strange today: The 3 Pylontech US3000C's were at SOC 56% and the 5 Pylontech US3000's were at 76%. The system is showing 68% overall SOC. Does anyone know why this would happen and how to correct it? Many thanks! Deon Can you place a picture of the cabling between the batteries. Any reason why only 3 show cycles?
February 3, 20242 yr Author Hi I don't know why. I see also there are only 3 serial numbers. I've attached the photo... Cheers
February 3, 20242 yr 23 minutes ago, Deonbayly said: Hi I don't know why. I see also there are only 3 serial numbers. I've attached the photo... Cheers The 1st thing I would do is to use a busbar for pos and neg. Take each Pos or every 2nd Pos to the busbar and the same on the Neg side and the busbar to the fuse disconnect en route to the inverters.
February 3, 20242 yr Author Thank you, I will investigate how I can do that the easiest way! Much appreciated!
February 3, 20242 yr 18 hours ago, Deonbayly said: Does anyone know why this would happen and how to correct it? Well, batteries are aging differently depending on quality. One noticeable aging parameter is internal resistance. It is responsible for unequal charge and discharge currents on parallel connected packs. The storage capacity may also be affected by aging. On the other hand I would seriously question the reliability of the BMS readings. There is not much you can do about aging. What SoC is concerned its best to refer to battery voltage. I know that's difficult since the voltage/SoC curve is very flat. However I delegate the charge management entirely to the inverter based on battery voltage - no BMS connections. The charging failure could be due to false information from the BMS to the inverter. Edited February 3, 20242 yr by Beat
February 4, 20242 yr Were all batteries at 100% SOC when firs connected up? Did you update the BMS to inverter cable as it changed? Are the US3000C on firmware version 1.7 or above? This is from Segen Solar: Source: https://portal.segensolar.de/reseller/docs/US3000C and US3000 Mixture Installation.pdf You could let them charge until the US3000 have reached 100% and then disconnect them and charge the US3000C to 100% and then reconnect them all to see if that balances them again. Edited February 4, 20242 yr by jumper
February 4, 20242 yr 30 minutes ago, jumper said: Were all batteries at 100% SOC when firs connected up? Did you update the BMS to inverter cable as it changed? Are the US3000C on firmware version 1.7 or above? This is from Segen Solar: Source: https://portal.segensolar.de/reseller/docs/US3000C and US3000 Mixture Installation.pdf You could let them charge until the US3000 have reached 100% and then disconnect them and charge the US3000C to 100% and then reconnect them all to see if that balances them again. What a boytjie From the picture one can see 3 are the C version. Also mentioned in the OP. It would be interesting to get a reply from @Deonbayly Edited February 4, 20242 yr by Scorp007
February 4, 20242 yr Author Thank you for your input guys! Were all batteries at 100% SOC when first connected up? This was a few years ago but I would have ensured they were at the same voltage but probably not necessarily at 100%SOC! Did you update the BMS to inverter cable as it changed? No I did not! I will contact my supplier to see if there is a different cable! Are the US3000C on firmware version 1.7 or above? I am busy doubling the size of my system so what I have done now to buy myself some time is install my new 8 Pylontech US3000Cs. The old batteries are therefore disconnected. I'll have to find out how to check the firmware version when they go back online. I will be creating 4 banks of 4 batteries in the new system. Thanks again for your help!!
February 4, 20242 yr Author oh my! Have I just gone down a rabbit hole! Had no idea these firmware updates were available or so important!
February 4, 20242 yr 1 hour ago, Deonbayly said: oh my! Have I just gone down a rabbit hole! Had no idea these firmware updates were available or so important! As a layman I just cannot see why the used pins had to change between versions built. Surely it's better to retain compatibility backwards for new products.
February 5, 20242 yr 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.
February 5, 20242 yr 22 hours ago, Deonbayly said: oh my! Have I just gone down a rabbit hole! Had no idea these firmware updates were available or so important! Yeah they are always updating the firmware to take care of issues and support new hardware, there may have been quite a big BMS change when the pins were updated. There is a ton of info on Youda's lab topic on pylontech batteries. Edited February 5, 20242 yr by jumper
February 5, 20242 yr 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.
February 5, 20242 yr Author Great, thanks! That's exactly what I'm going to do then! I just need to get clarity on the master batteries dip switch settings, particularly the startup process (eg when do you set the dip switches exactly? Some say in the beginning, others say after you've started up once and then shut down again?). There's a bit of conflicting advice as to how the process works. Cheers
February 5, 20242 yr 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.
February 6, 20242 yr 17 hours ago, Deonbayly said: Great, thanks! That's exactly what I'm going to do then! I just need to get clarity on the master batteries dip switch settings, particularly the startup process (eg when do you set the dip switches exactly? Some say in the beginning, others say after you've started up once and then shut down again?). There's a bit of conflicting advice as to how the process works. Cheers Dip switch changes need a restart of the battery to take effect, it is best to do it with the batteries switched off so they don't cause any conflicts while they are running. You can do it before you set them up, no need to start them up and switch them off again first. I reckon your dips are correct though because in your first post all 8 batteries are shown and a US3000C is the master shown at address 1 which I guess is the bottom battery from the temps.
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