Well, that’s a wrap!… Kinda. I have had some very mixed results when trying to commission the whole system. If you don’t feel like reading the whole article, the main problems were with the inverter and how the BMS interacted with it. The CANbus/BMS integration that I had assumed would work flawlessly did not really work at all. It seems that when companies make hardware too smart you run into WAY more problems. I’ll do my best to go into it all a bit further below. That aside, all the equipment is wired, running and as you will see to some degree up and running.

Battery Connection

Battery Connection to inverterThe first item on the agenda after the last post was to connect the batteries to the inverter. This was super simple. A couple of lugs later and voila done! The only issue I ran into was that the 35mm2 lugs I used would not fit through the cable glands properly. Lesson learned, terminate the cable after feeding through the cable gland. If you’re running a GW5048D-ES then it suggests 25mm2 cable which would probably fit with the lug through the gland, but I decided on a heavier gauge cable. Also, try and keep the cable run short to minimize any voltage loss on the cable. You can calculate this but at less than a meter, I assume the cable loss would be negligible.

Batrium CANbus to Inverter Connection

This had me stumped for a while, however, we eventually got through it. The GW5048D-ES came with a dedicated BMS cable. This cable at one end only had 3 pins terminated. After a bit of investigation, I found that the Blue pin = CAN-H, White/Blue = CAN-L, and the Orange is GND. In the image gallery below you can see the extract from the manual. Now I am no expert on the CANbus protocol but it seems that having a 120ohm resistor on each end is pretty important. The Batrium Watchmon 4 came with the resistor installed and I was able to find some clear instructions on the Batrium website for which pins to connect to.

At first, I did not connect the GND pin, It still seemed to work, however, I eventually connected it with no significant change in performance. Also of note is that I connected the BMS cable from the BMS port on the inverter to the CAN/H/L pins on the Watchmon. See the Gallery below for a few pics of connection.

(Almost) A complete Failure

After connecting the CANbus cabling, I attempted to configure the Batrium software to talk to the Inverter. As it turns out the only way I could get Batrium to talk to the inverter was in the integration settings in Batrium and select the “Project Lychee” integration. This integration mimics an LG RESU 6.4 battery. Thus on the Inverter and inside the PV Master App (Goodwe Configuration Tool) I had to select the LG RESU 6.4EX battery type. I was then able to confirm in Batrium that CAN comms were working. What you need to look for is that batrium transmits and receives.

Now that I had Batrium Communicating with the inverter, surely it would just be a few tweaks of Batrium?… How wrong I was. At first, all looked good, the charge cycle completed at the values I had set in Batrium and all was well. I started running into issues during the discharge cycle. The inverter could not make up its mind if it wanted to discharge or sit at idle. As you can see from the video below, keeping an eye on the “Shunt A” value. That is what is happening on the BMS shunt.

So where am I at now?

So after much back and forth with both the Batrium support team and Goodwe, no one can or wants to help me. I paid $85 for Batrium support in which they basically told me it was an inverter issue and Goodwe told me to use an approved battery. Boooo! So, for now, it looks like the remote integration is a no go. Not all is lost though, the inverter actually has a “self Define” battery option. This option is designed for Lead Acid batteries and has a few settings that can be configured. Such as Battery Capacity, Voltage Charge Target (56.7v in my case), Charge/Discharge Current (20A/20A to test.) and some SOC protect percentages. I have since been using these settings for a few days now with no issues. The inverter charges nicely and cuts of at set voltage. I am yet to run the battery down to test the SOC protect. That is next on my list.

If you missed the first parts of the build.

Part 1 – Recycling batteries
Part 2 – Building Packs
Part 3 – Fusing and cell protection
Part 4 – That’s a wrap