So I'm looking at replacing my Kodak Off-Grid inverter with a hybrid from either Sunsynk or Deye.

From what I understand there is a particularly chronic bug with both brands where they overcharge Pylontech batteries, essentially ignoring the BMS set points for voltage.

My questions:

• Is this true for all Sunsynk/Deye variants or just some?
• Has a software based workaround been found yet?

I realise one could simply disconnect the battery comms and manually set these charge values, but I'd prefer to be able to work with/use SOC values.

The problem comes where an installer or owner does not setup the inverter properly. There is an option that is called BMS_Err_stop. A lot of installers & users have no clue what it means. Basically it will shutdown the inverters output or battery usage if there is a Communication error or the cable is pulled out. 

Why is this important? 

Because if the comms stops the Inverter wil be running blind on usage settings that might be out of limits of the BMS & then this problem is encountered. A simple tick on this menu option on the battery page can save you a lot of hassle. The inverter is perfect. The installer or end user needs to know how to set it up properly. It's a human problem not a machine one. 

13 minutes ago, Steve87 said:

There is an option that is called BMS_Err_stop. A lot of installers & users have no clue what it means.

You are absolutely right ! there was a bug in the firmware maybe 1-2 years ago that was causing f58 errors all the time so the advice was to disable that so it would stop. That reminds me that i have to probably go turn mine back on .

34 minutes ago, Steve87 said:

The problem comes where an installer or owner does not setup the inverter properly. There is an option that is called BMS_Err_stop. A lot of installers & users have no clue what it means. Basically it will shutdown the inverters output or battery usage if there is a Communication error or the cable is pulled out. 

Why is this important? 

Because if the comms stops the Inverter wil be running blind on usage settings that might be out of limits of the BMS & then this problem is encountered. A simple tick on this menu option on the battery page can save you a lot of hassle. The inverter is perfect. The installer or end user needs to know how to set it up properly. It's a human problem not a machine one. 

Have seen this mentioned as part of the setup, but do we know for a fact that is the root cause of this?

i.e. is this a symptom of lost comms (in which case inverter decides to pick voltages) or misinterpreted/ignored comms.

 

 

 

Edited July 9, 20233 yr by Acheron

I would put my money where my mouth is, that this is exactly where the problem lays. The BMS tells the inverter how to behave wrt to Bulk, float, capacity etc. If this Comms was never established nor was it Protected if that Comms was dropped then the inverter will run on it's last User settings & I can tell you that those settings are way outside the limits of a Pylontech 15s battery. 

I have inspected a lot of sites where this was the case. Inverter comms never established, a normal 1:1 RJ45 cable plugged in & the owner none the wiser. That is how a lot of installers install. 

It's sad to say but this is common place. If that little BMS_Err_stop is ticked you will never go outside the envelope of the BMS. The inverter will stop using the battery & that's a fail safe design. However, having this not ticked opens your little Pylontech to a lot of abuse possibly. 

A machine is only as good as it's operator has set it up to be. Rubbish in = Rubbish out. 

Edited July 9, 20233 yr by Steve87

14 hours ago, Steve87 said:

I would put my money where my mouth is, that this is exactly where the problem lays. The BMS tells the inverter how to behave wrt to Bulk, float, capacity etc. If this Comms was never established nor was it Protected if that Comms was dropped then the inverter will run on it's last User settings & I can tell you that those settings are way outside the limits of a Pylontech 15s battery. 

I have inspected a lot of sites where this was the case. Inverter comms never established, a normal 1:1 RJ45 cable plugged in & the owner none the wiser. That is how a lot of installers install. 

It's sad to say but this is common place. If that little BMS_Err_stop is ticked you will never go outside the envelope of the BMS. The inverter will stop using the battery & that's a fail safe design. However, having this not ticked opens your little Pylontech to a lot of abuse possibly. 

A machine is only as good as it's operator has set it up to be. Rubbish in = Rubbish out. 

So in essence the safest thing to do would be to immediately, before connecting the battery, set up the User values to what the Pylontech is specced for and switch on BMS_Err_stop.

Then connect batteries (with correct cable) and monitor charge behavior closely. Should it fall back to user settings then at least they wont be out spec.

If it continues to charge to much higher voltages then the issue is elsewhere.