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Charge starting battery: BMV 712 relay vs MPPT SmartSolar Load Output

I have an older PWM charge controller which will charge both the House and Starting batteries. I am getting more solar panels and want to upgrade to MPPT, but MPPT charge controllers generally do not support 2 battery banks.

  • Assume I start with a single MPPT SmartSolar or BlueSolar controller

What would be the best solution?

  1. I could use the Load Output and wire that directly to the starting battery, and set a rule for the Load output to turn on the load when the house battery is between X and Y volts. Pros: doesn't require more equipment. Cons: the bigger MPPT controllers don't have the Load output at all, so I'd have to stay with the lower capacity models.
  2. I could get a BMV 712, and use its relay output to control a relay which connects the House and Starting batteries, and use a similar voltage-based rule (On between X and Y volts)
  3. Some other Victron product - battery isolator or combiner or...?


MPPT - Solar Charge ControllerBMV Battery Monitorstarter battery
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