Solar Shunt Prototype Project Question

Question:

I am getting a solar panel with an integrated lithium battery that’s 50Ah for a prototype project. They claim they have an RS485 option to see the charge status but not sure how all of that would work with Victron and if it’s worth it as my cellular modem doesn’t support RE485.

I was wondering since the solar panel hands off on the battery side a barrel connector would it be sufficient to grab the negative side of the 12v lead and put a bunt in it to see the charging and discharging or would the gauge of wire be too small and insufficient to get data?

Thoughts?