Everything started with the fact that the MT-5 display wasn't what I really needed. I was in the need of checking the charging from the device using the battery: my trusty Raspberry pi (1 B at the time). I managed to stumble over this instructable (https://www.instructables.com/id/Use-Arduino-to-Com... and git project (https://github.com/xxv/tracer/). So the code and research isn't mine.

But this was made for the arduino, (why use a USB and arduino when you have the capability on the raspberry pi?)

So i bought the EP solar MPPT solar controller from eBay + MT-5 display. That got me thinking that it should be possible to collect and store the data for later use. Said and done I started to search after the protocol specs and found what I needed here [Protocol] and as a nice bonus there where some code for arduino and python.

So with this information and code this was quite a easy task.

The result

Step 1: (Optional) Try on a Arduino.

You might consider this step to make sure you have hooked up everything the right way. Since the arduino is a little bit more forgivning then the raspberry pi (only 3.3v and will die if you hook it up wrong).

On my RJ45 cable it was:

arduino pin 10 to Full blue

arduino pin 11 to green/white

Arduino pin GND to orange

Double and triple check this before you hook it up, there are some 12v pins!

Arduino code: Arduino code

Does it work?

Great! Go on to the next step.

Else check your connections