Pylontech batteries are no longer communicating

DIY
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1

Hello everyone, until recently my system was working perfectly. I basically have an off-grid system; when there was no more sun, the three Pylontech batteries discharged evenly. When the remaining charge reached 20%, I would go down to the basement and switch over to mains power. We now have a new 380 V power connection. I reconfigured the system so that switching over would no longer be necessary. It worked for a while. When the remaining charge reached 20%, the system automatically switched over to mains power. Now I’ve noticed that the batteries are no longer communicating with each other. The middle battery is showing 18% on the Cerbo, which is correct. But the other two still have four lights on. Why is the Cerbo only showing the charge level of the weakest battery? I have three MultiPlus-II 48/3000 units.

Yesterday I switched off two batteries and connected the first one. The Cerbo showed 68%, which was good, but by the evening it was still at 56% and the system was drawing power from the grid. So something is going wrong here. This is a lot of text, but I didn’t know how else to explain it. I hope someone here can help me.

Regards,
Klaus

2

Hello Klaus,

Have you checked the battery communication cables? You say you’re on 380 Vac? And your MP2 system and batteries are connected to your mains supply?

3

Hi Klaus :waving_hand:

Have a look in the device list under your (hopefully) detected Pylontech batteries / Details and check whether your 3 modules are shown there.

If they are, it’s very likely that the SOC in one of the batteries has simply drifted out of sync with the others. That’s nothing to worry about for now. The problem with this is always when the overall SOC is used for some kind of control task. The weakest battery will therefore always remain the weakest one … unless you carry out a full cell equalisation / balancing. This is especially necessary right now, in winter.

Set “Keep batteries charged” and then see how your batteries behave.

4

Hello Yvon62, the cables are connected correctly and the Multis are feeding power into my grid. MP2 system?

5

Do you see how many modules are online on the cerbo?

IMG_20261025_122514
IMG_20261025_1225141080Ă—730 136 KB

6

Hi Steffen, only one battery is showing in the device list. But I’ll try changing it as you described. Thanks

7

When I switch to battery hold, they charge from the grid at 5,000 W :see_no_evil_monkey:

8

… it seems the CCL (the charging current) is definitely higher than for just 1 Pylontech battery :thinking: … Could you please take a picture of the battery’s system menu mentioned above …

but anyway … take a picture of the batteries …

“Yesterday I switched off 2 batteries and connected the first one” ??? … why did you do that?

maybe you’ll need to restart the cluster via the master so that the whole system is sent to the GX again.

9

Sorry, I don’t have this setting. How do I get to it? I can only get to the device list, and there it only shows me a battery.

10

Do you have the batteries connect to the cerbo with a can cable?
Use the small jumpers that pylont provide or a straight cable for the battery interlinks using the rs 485 ports

11

Then you have a different problem. First check whether you can see all the required devices, including any grid meters, if there are any.

12

Which batteries exactly do you have?
And do you perhaps also have the cables/converters for the console port(s) on those batteries?