Building a cable to connect my EPever charge controller

I recently purchased an EPever Tracer AN solar charge controller. I chose this charge controller because it is one of the only controllers on the market which have a built in Lithium battery cold temperature protection feature. When I purchased this controller I thought it would be easy to get it working with my Raspberry Pi using the official EPever USB to RS-485 cable. It did work fine on Windows but on Linux after several days of trying I gave up trying to get it working on Linux. The chip used in this cable does not have up to date Linux drivers and I could not get drivers that I found on Github working reliably.

After some research, I decided to have a go at making my own cable instead which would use a chip that already has reliable Linux drivers.

Parts

Building the cable

The first step is to connect the serial port breakout to the USB connector and wire the serial using the jumper cables. They should be connected to TXD -, TXD+ and GND. RXD is not used for RS-485 communication.

The next step is to connect the jumper cables and the Cat 5 cable to the RJ45 breakout terminal block, connecting to terminals 3, 5 and 7.

TXD- goes to terminal 5
TXD+ goes to terminal 3
GND goes to terminal 7

Your cable is now ready to connect to your computer and the charge controller.

On Linux the cable will show up as something like /dev/ttyUSB0. You shouldn’t need to install any additional drivers. I recommend using my Python library to communicate with the charge controller https://github.com/rosswarren/epevermodbus.