I have a Multi 5000/24 with ESS assistant.
4 x 250/80 Mppt connected to a bank of 2s 6p 12v 135aH batteries.
I also have a PV system on the roof that feeds into the multi to charge the batteries when we have excess solar. (I inherited this when I bought the house with a good feed in tariff)
The DC coupled battery are set not to feed in.
I would like to add another 12 batteries to this system.
I dont have BMV or smart shunt.
I understand that I need to reconfigure the multi with the new battery bank capacity but how does the multi know the % of SOC?
Would I be best to buy BMV.?