Adding solar to BMS 12/200

DIY
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Sailboat system: 2x Lithium Smart 12.8V/200Ah, Smart BMS 12/200, MultiPlus 12/2000 on System+, starter battery + alternator on the Alternator/Starter Bat+ port, Cerbo GX for monitoring. Cell voltages are healthy and balanced (4x 3.38V). I’m adding 2x SmartSolar MPPT 75/15 with 2x 100Wp panels.

Two constraints: the VE.Direct ports of the 75/15s are needed for the Cerbo, so I can’t use them for remote on/off. And the MultiPlus is physically hard to reach, so running remote wiring there isn’t realistic either.

I see two options:

Option A: connect both MPPTs to the starter battery and let the BMS pass the charge to the lithium through the alternator port (AB cable moved directly to the starter battery post, with the MEGA fuse). The MPPTs would be set to ~14.4V absorption / 13.5V float to compensate the voltage drop across the port; the BMS charge limit (14.2V) and cell protection provide the cut-off. Advantage: the MPPTs always see a battery, no extra components.

Option B: connect the MPPTs to System+ through a Smart BatteryProtect 65 in Li-ion mode, driven by the BMS Charge disconnect output (charger on IN, per manual section 3.3.5).

Questions:

  1. Which option would you recommend? Any objections to continuous solar charging through the alternator port (thermal, duty cycle)?
  2. For option A: are 14.4V absorption / 13.5V float the right MPPT settings, given the drop across the AB port and a flooded starter battery permanently on that point?
  3. For option B: how do you deal with the known E1 inrush error when the SBP re-engages, especially since DVCC/shared voltage sense can push the disconnected MPPT output above 16V?

Thanks!

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In the meantime, I’ve successfully charged from solar via an MPPT connected to the alternator port of the Smart BMS 12/200. The starter battery is also connected directly to this port, so both are connected to output 1 of a Victron ArgoFET.