Month: March 2023

The other day, I connected my BYD Battery-Box Premium LVS 8.0 to a Victron MultiPlus-II 48/3000/35-32. Here are the steps I took to do it and some errors I ran into.

The Battery-Box needs to communicate via CAN with the inverter. And as Victron inverters do not come with a CAN port by default (unless you go for a MultiPlus-II GX or EasySolar-II GX) we need a GX device. Originally, I wanted to use my Victron Cerbo GX for that, but since we moved into the caravan the device is gone missing. Luckily last year, I supplied myself with a couple of Raspberry Pis (at least model 3 and 4 are supported) that could run a Venus OS and act as a GX device. And as I was not the first one doing that, I thought it would be just too easy – well, it was easy after I did everything right.

Normally, Victron requests to use a VE.Can to CAN-bus BMS Type A cable to connect to a BYD battery. This is actually an ordinary CAT 5e network cable with RJ45 connectors where only the relevant CAN pins (and GND) are connected.

Note: on the original Victron Type A cable, all three pins seem to be connected:

In order to screw the wires to the CAN hat terminal, I used uninsulated ferrules. Otherwise the Cat 5e wires would have been too soft and light for the terminal.

Installing Venus OS on the Raspberry PI 4

For the Raspberry PI 4, I followed the documentation and installed the standard (and not the large) image. At that time, v2.93 was the newest version (see here for directory of all versions). I uncompressed it and used Win32DiskImager to write the OS to a MicroSD card (all done on a Microsoft Surface Go2 running Windows 11).

I then enabled remote access via SSH by becoming superuser and setting a root password.

Note1: at first, I did the install with a Raspberry Pi 3 Model B V1.2 which also worked fine. However, the CAN device on the Victron UI then did not show any packets but worked without problem.

Note2: The Raspberry Pi 4 is a model B Rev. 1.5 (I mention this, as I saw comments that indicated that there might be a difference between different revision from 1.2 onwards).

Note3: I activated the “Mobile” tile to be able to change the charge current via the overview screen.

The CAN driver then had to be installed separately. As I did not have direct internet access from the Pi, I used the offline install method with a USB memory stick.

Installing SetupHelper

As written in the documentation, I copied the compressed installation files as venus-data.tar.gz to the root of the USB drive and restarted the Pi.
To verify the automatic installation was successful check if there is a new menu item Package manager at the end of the Settings list. If not visible check if you can find SetupHelper in /data. You can always manually copy it from the SDCard (use mount to see where the card is mounted) and then run setup yourself. I did a reboot after every package.

Installing VECanSetup

Same procedure here. Copying the compressed installation files to the SDCard as /venus-data.tar.gz. Then run the package installation manually if for whatever reason the automatic install does not succeed. See below what the package manager should look like after the installation of both packages.

Installing the driver

Configuring the driver had to be done from the terminal. There was a minor issue for me which I did not get right the first time. When asked to install an interface via the i option I actually had to type in a hat. I named the device hat0 and after the reboot it showed up as hat0 (can8) can8 spi0.0. In my case it was the “Waveshare 1-channel CANbus Hat 12 MHz crystal” (check the imprint on the silver part on the hat to see the crystal speed).

Configuring CAN bus

There is really not much to configure. The only option under “Services” is to set the communication speed which is 500kB/s for BYD. If the CAN adapter does not show up make sure the correct type has been selected in VeCanSetup. For me it just worked out of the box.

Before the BMS is connected the CAN should show up as ERROR-PASSIVE. As soon as the communcîcation worked it changed to ERROR-ACTIVE.

Note: When I tried with the v2.93 on the Raspberry Pi 3 the RX/TX counters were always empty (but nevertheless worked). Via ifconfig the packets were correctly shown. But with the Pi 4 traffic was shown on the UI right from the start.

I did not connect the CAN cable at that point but configured the Battery-Box and the inverter first.

Commissioning the inverter

I used a USB MK3 adapter with an RJ45 Cat 5e cable connected to the VE.Bus of the inverter to configure the MultiPlus.

I used VEConfigure 3 and VictronConnect (to be able to configure via VictronConnect I had to use the zzz password to get out of the read-only mode).

First, I updated the firmware of the MultiPlus via VictronConnect and then continued with VeConfig.

Basically, I set the inverter to off-grid and did not enter a country code. For the battery type I selected “Lithium Iron Phosphate” and accepted the default settings. I set the “AC current limit” to a maximum of 20A (the maximum my generator could handle) and activated the option to have it overruled by “Remote” (which can also be done via the GX Remote Console or VictronConnect).

I also activated DVCC to later have the BMS tell the inverter when to charge and how to discharge. This was pretty much it. So I connected the MultiPlus via the VE.Bus and the MK3 cable to the Raspberry where it showed up instantly.

Commissioning the Battery-Box

After assembling the battery which conisted of only stacking both battery modules on top of each other followed by the PDU on the very top I connected the BMU via the grey RJ45 to the PDU. After turning on the top most battery the BMU started as well and I was able to connecto to the WiFi of the BMU from the BeConnect app (Android or Windows both worked for me, the latter actually showed more information).

Via the app I pre-downloaded a current firmware and after switching to the BYD access point I applied the firmware (actually two different firmwares). After some waiting the new firmware had been applied and I could configure the basic settings: inverter manufacturer, number of battery modules.

At this stage I connected the 35mm2 cables from the battery to the inverter. I bought the cable preconfigured with the battery. And I used a Littelfuse JLLN-125X (class T) as a fuse between both devices.

Connecting the battery to the Venus OS

And then I connected the BMU to the GX. After some seconds, the inverter clicked and started charging. Essentially, DVCC turns on automatically (even if turned off before) as soon as the CAN communication is established.

In the GX overview the battery appeared and gave some additional information (see next section for details). All parameters between battery and inverter were exchanged automatically.

Things I noted

1. The battery turns itself off after a while when no communication via CAN is possible. This behaviour is described somewhere in the BYD manuals.
2. Charging the battery does not work when no CAN connection can be established. The inverter stays in “Absorption” mode with a current of 0A.
3. A more detailed description of the pin layout can be found on the BYD manuals. See images below.
4. The GND pin is not required for communication between the BMU and the VE.Can GX. Only BLUE for CAN-H and BLUE-WHITE for CAN-L are going into the CAN hat.
5. In addition to the official web site bydbatterybox.com the web site eft-systems.de provides additional information and downloadable documentation.
6. When charging the Battery-Box for the first time, I eventually reached a 100% SOC. Until that point the charge current stayed nearly constant at around 30A (Bulk). It decreased to around 1.2A and the inverter turned to “Absorption” but never stopped charging. At some point one of the cells reached a voltage of over 3.7V which resulted in a warning on the GX. Nevertheless, charging continued. I manually switched off the charger after the second time I received a warning due to high cell voltage. I would have expected to have the inverter automatically stop charging at a 100% SOC.
   Maybe the BMS only measures the charge voltage limit (CVL) which is defined as 58.4V and not the individual cells?
7. The cells in a battery were not really well balanced (delta >= 100mV). I would have expected a better balancing. Actually, I do not know if the BMS has a balancer at all. I could not find anything in the documentation.
8. Each LVS 4.0 has a capacity of 78Ah @ 51.2V = 3993.6Wh. The GX shows this information in the “Details” item within the battery. I could not find this information in the manual.
9. The BYD manuals state, that the lifetime of the battery can only be achieved at 0.2C, which limits a single LVS 4.0 to 798.72W (or 1597.44W for a LVS 8.0) – this is a ridiculous small amount.
10. Charge current was initially restricted to 38.4A by the battery, only after a day or so, the charge (CCL) and discharge current (DCL) went up to 128A. In my case the inverter only support 35A max, so no issue with that.
11. Startup sequence
    Start top-most battery first by pressing the power button for a couple of seconds; then start the BMU if not automatically started; next start the inverter; then start the GX (in my case currently on the AC side).
12. Shutdown sequence
    Turn off the inverter; turn off the BMU; turn off the individual batteries (keep buttons pressed for a couple of seconds); GX turns off automatically.
13. Adding a CAN hat in VeCanSetup needs to be entered literally as a hat.
14. Though I set the AC charge current to 20A the inverter only drew 16A at most.
15. The WiFi of the BMU cannot be changed, nor the password.

Future improvements

• I want to connect the Raspberry to the DC side with a 48V/12V step-down converter and a 12V to USB-C adapter. Inbetween I want to add a power bank, so the GX can be configured even if all power sources are down.
• Replace the CAN hat with a USB CAN adapter
• Strengthen the connection of the CAN wire to the CAN adapter
• Try a Raspberry Pi Zero 2 W (when they become available again).

Conclusion

All in all, the installation was straightforward. A couple of uncertainties are probably normal when doing this the first time. I would have expected more documentation (articles, videos) for this to be around. But I could not find anything for a BYD, Victron, VenusOS via Raspberry setup. Maybe others are only using a Cerbo GX?

The batteries are well built (all IP55) but extremely bulky and pricey. With around 400 CHF per KW this is more than 300% of regular LiFePO4 cells. But nevermind, lead and delivery times are in the magnitude of months.

I would have liked the BMU to be integratable into one of the PDU boxes. Now it is just hanging around separately.

Would I buy another Battery-Box? Probably not – too pricey. But good for starters. Plug and play when used with Victron and a Cerbo GX.