On 2024/12/14 at 4:30 AM, Coulomb said:

I'll just post my recommended Pylontech battery settings, for those not having the BMS control the charge via the BMS to inverter BMS port cable. It's in dire need of redoing, but the important numbers are there: 52.5 and 51.8V.

These figures are a little higher than I use myself when adjusted for 16S (Pylontech is 15S), but were a consesnsus amongst actual Pylontech users. 

Edit: The maximum current setting is for the original 2.4kWh models. Adjust accordingly for recent models' total capacity. 

Hi @Coulomb,

 

Thank you for these detailed instructions.

After this thread, you probably know by now that my US2000 is dead, and not going to be replaced, but I have two more US 2000 and one US 3000 all connected to my two Axpert 5K inverters.

I have started changing these settings as you indicate above.  I do all changes from Solar Assistant, not on the physical unit itself.  There do seem to be some terminology differences also.

1) I use an app called Solar Assistant, not ICC.  Should I still then make program 12 46V also, or is that exclusively for ICC, and no other control apps?  On SA it is called "To grid voltage".

2) I am somewhat unclear on program 02.  In my instruction booklet it says I should add the solar and the grid together, and that should be my max, and in Solar Assistant I have grid set to 30A max charging, and the solar charging is set to a max60A.  Now, as I understand it, These two max charge Amperage settings are what controls program 02.  It seems to me that program 02 is a single setting on the inverter, but in Solar Assistant I have the two separated options.  I am not clear on this at all.  If you could assist, I would appreciate very much.  On SA it is called "Max Charge current" (60A) and "Max grid charge current" (30A).

3)  When I try to change program 26 or 27 (they are presently at 53.2V) I get the response:  "Rejected" from Solar Assistant.  When I go to the physical units and attempt to set it via their LCD screens, then it simply does not change.  I can try to increase or decrease, it just remains at 53.5.

Your help is highly appreciated.

 

I attach a screenshot of the battery settings area, as it may help?

 

Edited February 10, 20251 yr by Riaan Eloff

19 hours ago, Riaan Eloff said:

I have started changing these settings as you indicate above.  I do all changes from Solar Assistant, not on the physical unit itself.  There do seem to be some terminology differences also.

1) I use an app called Solar Assistant, not ICC.  Should I still then make program 12 46V also, or is that exclusively for ICC, and no other control apps?  On SA it is called "To grid voltage".

Heh. When I started the Pylontech recommended voltages table, ICC was the dominant monitoring software. I guess that was a while ago now. I suspect that ICC worked a little differently than Solar Assistant does now.

I also have to come clean that I don't use a Pylontech or any other battery with a factory built-in BMS. My battery has a BMS, but it's a custom one totally different to any factory BMS.

It's also been a long time since I roughly knew how the BMS control via RS-485 or CAN bus works.

I note that your battery type above is Pylontech BMS. That means that the Pylontech BMS is calling the shots. Was the battery type that way when the damage occurred? It's really unfortunate that the BMSs all seem to work with very high voltages, and seem to assume superhuman control systems that Voltronic inverters in particular can't live up to.

When the inverter's battery type is Pylontech or one of the other several BMS types, settings like the bulk/absorb/CV battery voltage and float voltage are completely ignored. My table, as I noted in that post, is for people who aren't using the battery BMS connected to the inverter via the RS-485 or CAN bus cable. Are you connecting the BMS to the inverter directly, or to Solar Assistant? If the latter, I'm afraid that I don't know how it really works. It may be that SA tells the inverter that the battery type is USER, and manages the battery using messages from the battery BMS as a guide.

20 hours ago, Riaan Eloff said:

2) I am somewhat unclear on program 02.  In my instruction booklet it says I should add the solar and the grid together, and that should be my max, and in Solar Assistant I have grid set to 30A max charging, and the solar charging is set to a max60A.  Now, as I understand it, These two max charge Amperage settings are what controls program 02.  It seems to me that program 02 is a single setting on the inverter, but in Solar Assistant I have the two separated options.  I am not clear on this at all.  If you could assist, I would appreciate very much.  On SA it is called "Max Charge current" (60A) and "Max grid charge current" (30A).

The inverters themselves have two battery charge current settings: maximum total charge current, and maximum utility charge current. I think that the idea is that you decide the total charge current based on the battery manufacturer's recommended maximum charge current, but the maximum utility charge current can be lower than that, in case you don't want to spend too much money on utility charges, or the generator has a limit, etc. I note that maximum total charge current is one of the settings that gets taken over by the BMS: "If selected, programs of 02, 26, 27 and 29 will be automatically set up. No need for further setting." Setting 02 is the maximum total charge current, 26 and 27 are the bulk/absorb/CV and float battery volage settings respectively, and 29 is the low DC cut-off voltage.

20 hours ago, Riaan Eloff said:

3)  When I try to change program 26 or 27 (they are presently at 53.2V) I get the response:  "Rejected" from Solar Assistant.  When I go to the physical units and attempt to set it via their LCD screens, then it simply does not change.  I can try to increase or decrease, it just remains at 53.5.

That's resumable because as above, the BMS takes over these settings.

What is setting 05 on the inverter itself? Presumably either PYL or USE.

Sorry I can't be more help.

 

23 hours ago, Coulomb said:

Sorry I can't be more help.

 

Please, no apologies.  You are more help in these forums than pretty-much every customer-service-help-line has ever dreamed of being 🙂

I honestly appreciate your effort and pointers above.  Also the clarifications on how you use your system and what you use.  I am going to continue the conversation via email with Chris from Pylontech, and use whatever he advises alongside your original post, and consider the points you made above.

If I find that I get to a dead end, I may be so forward as to bug you again 🙂

Cheers

@Coulomb and all who may find this thread useful,

 

So, when I select Pylontech BMS as my battery type - as you say - I cannot change the max charge or max float.  When I change to "USER", then I can change those two.

All other settings can be changed with either Pylontech BMS or USER.

If you, or anyone else reading this could advise:
If I switch to "USER", I understand that the Pylontech BMS will no longer be read into the software app, BUT, will the BMS on the actual unit still be functioning correctly?

I did also recieve a response from Chris.  He recommended that with the Axpert unit I own, I should set the max charge voltage t0 52V.  That is the only info he passed on to me, though, so I've set up all others as close as I can to @Coulomb's original recommendations.  I did, however, ask him the same question as I ask here in the previous paragraph.  My concern is, that with the translation to Chinese, some of what I am asking may be lost, and we may miscommunicate.  So, if anyone can comment on this, it would be appreciated.

Thus, my system is presently running as follows:

Battery type - User

Charger source priority - Solar only

Shutdown battery voltage - 45 V

To grid battery voltage - 48 V

Back to battery voltage - 50 V

Battery float charge voltage - 52 V

Battery absorption charge voltage - 52 V

Max charge current - 60 A

Max grid charge current - 30 A

 

One other question: if the battery type is "User", will the percentages and voltages etc, that are displayed in the software still be read from the BMS, or from the batteries themselves, or at all?

 

Thanks in advance for any input folks.

On 2025/02/13 at 3:13 AM, Riaan Eloff said:

If I switch to "USER", I understand that the Pylontech BMS  [ data] will no longer be read into the software app, BUT, will the BMS on the actual unit still be functioning correctly?

Yes, but the BMS and inverter can no longer work together cooperatively. Suppose one cell voltage goes too high while charging. With battery type PYL, the BMS can send a message saying "discharge OK, charge not OK". If the inverter is agile enough, it can stop charging for a while, the cell voltage relaxes, the message changes to "charge OK", and things proceed smoothly. With battery type USEr, the inverter only has the total battery voltage to go on, and it looks fine, so it continues to charge. The BMS is now forced to disconnect completely from the inverter, with unknown effects on inverter operation. 

Actually, I've only recently learned that it's possible for the BMS to prevent charging while still allowing discharging. I guess to the inverter it appears that suddenly the battery is full, as the battery voltage rises very fast. If a sudden load appears, then the battery voltage will drop quickly, and the battery can support that sudden load. So maybe they cooperate fairly well after all. 

For those curious, the technical details are explained here:

https://diysolarforum.com/threads/bms-mosfets-explained.29318/

Note that in practice, the two MOSFETs are actually a pair of sets of MOSFETs in parallel, each pair connected in series.

I learned something today 🤓.

So as for whether Axperts are better off with PYL or USEr battery type, I'll have to ponder more. Bear in mind that I don't own one of these and the home grown BMS I use doesn't have these MOSFETs. 

On 2025/02/13 at 3:13 AM, Riaan Eloff said:

One other question: if the battery type is "User", will the percentages and voltages etc, that are displayed in the software still be read from the BMS, or from the batteries themselves, or at all?

It's all or nothing. With battery type USEr, the inverter doesn't talk to the BMS, not even in "read only" or "peek mode". So the inverter assumes that the battery is lead acid (bzzzt!) and guesses the SoC based on battery voltage. That's rough and ready even if it was lead acid, but since it's actually LFP, it's almost completely useless at estimating the SoC.