So I tried to do some research on using a dc charger on the pv input side of an MPPT and didnt really find many people doing it (for good reasons and very few probably need this), I could find various people saying dont do it, bad things can happen, not the products intended use etc.... My reasoning is that I can make use of surplus A/C energy and in theory could trigger cheaper tarrif rates, increase charging currents beyond the mutiplus limits etc.. AND more importantly I want the batteries built in BMS to control charging rates through victron comms.
Anyway... as an experiment I wanted to test if this was possible and so far my small experiment seems fairly stable and useable.
Using a 150/35 MPPT with a regulated DC charger on the pv side seems to provide a nice steady charge current. The charger is 12-84v / 1-25a and I can fix both the voltage and current (claims to have all the usual protections). I set the MPPT to charge at a max of 20-21amps so that its pushing about 80% of the chargers rated max with a voltage of about 59v which seems to work well.
Have I overlooked anything obvious that could be a concern? I get this is a small scale limited experiment and not pushing massive a current to charge but it does have its other benefits that make this worthwhile (I feel).