Battery charging

[Wernito]

My boat has a starter battery and a separate house battery which is charged by a 220 V charger.
In what case can both batteries be charged from the same source and how should they be connected?

[a64pilot]

Most good chargers will charge up to three banks, simultaneously.
I'd first verify that your charger is a multi stage "smart" charger that monitors battery temp and adjusts charging voltage based on temp, and has multiple charging profiles for different battery types ,and ideally a programmable profile where you determine voltages.
If it doesn't, then you may want to consider replacing it.
I said may, boats have had "dumb" chargers forever and not sunk, but there is better technology available, if you don't already have it.

[barnakiel]

Our shore charger charges one bank only so I swap the red cable between the banks.

Our alternator charges the motor battery and a small Bosch relay relays the charge to the house battery (again, red wire only) - only when the alt is working.

b.

[ScottMeilicke]

We have a Blue Sea automatic charging relay. Once the voltage hits a certain point, just over 13v, it bridges the two banks so any of our charge sources will charge both banks. The battery chemistries should be the same.


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