Do Battery Combiners Alter Voltage?

Question:

Hi, I have a technical question about a Blue Sea SI-ACR.  I have spoken to Blue Sea tech support, but would like a second opinion before making my connections.  I run a bowfishing boat with a Powermax PM3-45 converter connected to a generator and charging my house batteries at all times (2 series 31 deep cycle in parallel.)  I have lots of amp draw with cabin lighting, stereos, etc.  This is the only way to keep my house batteries charged all night.  My motor is a Mercury 250 4 stroke.  I believe the alternator puts out up to 85 Amps.  Can I install an SI-ACR even with house and cranking batteries having their own charging source?  My concern is back feeding my alternator from my converter.  Not sure that this is even possible, but want to make sure.  I like the idea of having multiple systems to keep all banks full if possible.  Thanks in advance, Love your YouTube channel and learning tons from it. -Mark

Answer:

You are correct, battery combiners don’t alter or modify voltages, but simply parallel two battery banks together whenever a charging voltage is present. When activated (via battery charger or alternator), the battery combiner will share a charging voltage from one battery to other. Better to have similar battery chemistries when using battery combiners or instead to use a DC to DC charging converter between engine and house battery, consider the Victron product line: https://www.victronenergy.com/dc-dc-converters/orion-tr-smart - Jeff