Hi all

Since this is a cross technology battery and inverter question I thought I'd place it in this section, hope that's right? 

 

So I have a parallel pair of 5KW  Voltacon branded Axpert King inverters. Each have their own solar array, both feed a common stackof pylintech us2000 batteries and one has bms control of the stack. 

I have observed 

I can pull data between them in Watchpower, but that is as far as the 'parallel' function appears to go. The two inverter control panels are totally independent, I can set completely different settings on each and those settings are applied individually. Further the 2nd inverter doesn't realise it is bms connected to the batteries and must be put into 'user' battery mode so as not to go into fault. This causes the pair to not work very well together and to declare the batteries full/empty at differing times. 

Is this normal? 

Secondly, I have just bought some of the new voltacon branded 100Ah batteries, which they assure me are not compatible with the stack function of pylontech's own models (I believe this to be false information) despite being identical to the new pylontech 100Ah unit.

Is there any reason, why I can't have two separate battery stacks for the two inverters (since the inverters appear to be so independent anyway), each with bms control from it's respective inverter? 

New voltacon batteries here https://voltaconsolar.com/lithium-battery-100ah-5120wh-48v.html

Many thanks

 

Swen

4 hours ago, swenk said:

Further the 2nd inverter doesn't realise it is bms connected to the batteries and must be put into 'user' battery mode so as not to go into fault. This causes the pair to not work very well together and to declare the batteries full/empty at differing times. 

Is this normal?

My understanding is that yes you have to have the second inverter set as battery type USE, but if they are both in output mode PAR (setting 28), then the master should co-ordinate things. If BOTH inverters are set to battery type USE, you can have different settings for battery currents, like maximum charge current. But I think that those settings are ignored when one has battery type PYL or another BMS type.

I think it would not be normal for the two to consider the battery full or empty at different times. But maybe it's just that the SOC display on the one not connected to the BMS is wrong and can be ignored. Sorry, I have no experience using the BMS cables.

Hi Coulomb

Thanks for your reply. 

The issue I am facing is that the 2nd unit (not bms connected to the batteries) goes into bypass believing the batteries to be empty...  Even though the pair are in parallel and set up accordingly. 

Hence my question about a 2nd battery stack... One per inverter, bms both individually bms connected. 

Many thanks

 

Swen

16 hours ago, swenk said:

Hence my question about a 2nd battery stack... One per inverter, bms both individually bms connected. 

Oops, I missed that question. The manuals certainly say that the battery has to be common between all of them. I believe that's because the master figures out what current to charge at and so on, and the slaves just copy that behaviour, not figure out to to based on their own battery.

So: I certainly would not have separate batteries.

This is clearly indicated in the manuals as the previous reply suggests.

Hi

Thanks both for confirming. Yes I appreciate the diagram in the manual, it wasn't clear whether is was 'suggested' or mandatory. 

Thanks, I am now updating the firmware to see if I can improve the parallel functionality, to try to stop the 2nd inverter going into bypass when the batteries go below 50%. The master inverter is performing perfectly. 

I'll post back any additional info I learn. 

43 minutes ago, swenk said:

The master inverter is performing perfectly. 

Is the slave showing SL somewhere? It's almost as if the slave isn't actually a slave.

19 minutes ago, Coulomb said:

1 hour ago, swenk said:

The master inverter is performing perfectly. 

Is the slave showing SL somewhere? It's almost as if the slave isn't actually a slave.

Hi

Yes clearly showing SL. Agreed, that is the behavior I am seeing, although the fans always rev up in unison and loads are RELATIVELY evenly spread etc. 

Right at this moment is is really sunny, the batteries are full and it is showing fault 04 (low batteries) whereas the master with the bms cable attached is working just fine. Both of them agree that the battery voltage is 50.5V. 

I'll update the firmware and report back