Jump to content

Bms cable for 5kw axpert king and maxi-li 2x 50 ah


Recommended Posts

Good day Gents/Ladies


I am new to the forum but have read a lot on it.


I am in desperate need of the bms cable setup for above.  Probe that supplies the batteries just do not communicate the info from their side so that a person can make up a cable.


Everything seemed to work ok until i added a wind turbine recently. Now nothing gives me the correct state of the batteries. Not even the watchpower app.

I have 2 x 50ah batteries. I have turbine connected to main battery on bottom of rack, leads feeding from slave/top battery to the inverter. 


I just think that if i can get inverter to communicate with batteries many if my problems will be gone.


Has anyone got a suggestion please.





Edited by wareddel
Added pics
Link to comment
Share on other sites

Those battery modules don't look terribly mainstream.

So it seems to me you need to know:

* Does the battery BMS talk RS-485, CAN bus, other (e.g. RS-232), or not at all?

* What protocol does the BMS use, if any? This may choose the comms method, e.g. Axperts only talk RS-485 to Pylontech protocol. This determines what value to use for the Kings Battery Type setting (setting 05).

* What is the pinout on the battery BMS side?

* What is the pinout on the Axpert King side? This at least should be moderately well known; search Youda's build on this forum or search the AEVA website. Note that the Axpert pinout differs from the Infinisolar pinout, even though both are non-standard and both are made by the same company.

Link to comment
Share on other sites

3 hours ago, wareddel said:

Now nothing gives me the correct state of the batteries. Not even the Watchpower app.

I think you'll find that the inverter never did know the state of charge, and therefore Watchpower doesn't either, assuming that these battery modules are LFP.

If you can't get the Axpert or monitoring software (e.g. Solar Assistant) to talk to the BMS, you might consider using a Victron BMV, which has a shunt and measures Ah in and out, giving a decent estimate of the battery's state of charge. The inverter is estimating by a formula based on the battery voltage and assuming lead acid chemistry. That will never with with LFP chemistry, though it can be made to work OK with other lithium chemistries (e.g. NMC).

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Create New...