I have several banks of batteries on a boat, two larger banks 48v electric propulsion system with regen 12v house bank
Each has a charging source the 48 has regen up to 2kw while sailing The 12 has 120amp alternator They are set up and running well but isolated from each other. When either of these charging sources are running, I would like to charge both banks at the same time to make better use of the high output.

Wondering is this is a feasible solution: 12 to 48 alternator -> use a charger that is activated by the ignition (https://www.powerstream.com/dc-input-charger-12v-48v-1250w.htm) 48 to 12 regen -> a charger with a manual switch? or programmable VSR? (https://www.powerstream.com/DC48-12-charger-extreme-60A.htm)

OR would a DC/DC converters with voltage sensitive relay / isolators be better? 48v Batteries are valance lifpo4 12v are deep cycle lead acid

Thanks! Ryan

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    \$\begingroup\$ Some punctuation would make this much easier to read. \$\endgroup\$ – Blair Fonville May 14 at 2:03

DC-DC boost regulator will be more efficient than any Alternator (<< 70%) with low voltage protect set at 13V when 12V alternator is charging. Ref

  • \$\begingroup\$ thanks for the info but that wasn't really the question \$\endgroup\$ – Ryan May 16 at 15:08
  • \$\begingroup\$ The answer is there, use the 12 to 48V DC -DC boost regulator with the 13V threshold to automatically activate the charger when the alternator is running. \$\endgroup\$ – Tony Stewart Sunnyskyguy EE75 May 16 at 17:14
  • \$\begingroup\$ Ok, I misunderstood you. That makes sense. How do you control the charge though when the batteries get full... have a voltage sensitive relay isolate at a voltage? \$\endgroup\$ – Ryan May 17 at 5:09
  • \$\begingroup\$ This unit has the battery charger CC, CV and cutoff profile built in. It is adjustable behind the front panel for different chemistry. \$\endgroup\$ – Tony Stewart Sunnyskyguy EE75 May 17 at 5:20

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