Guest dual charger

[robhwa]

Which DC to DC charger are you using? I have experience with several (Victron and Sterling). Neither of these will "Priortize" the start battery, any more than a VSR does. (I am using a VSR between start and house--and the DC to DE to a 3rd battery bank--both in the RV and was in Thataway.

Renogy DCS50S...from the manual and online:
- Designed to charge service batteries from two DC inputs—solar panels and alternator
- 3-phase charging profile (Bulk, Boost, and Float) ensures your service battery will be accurately charged at the correct voltage levels to 100%
- Trickle charges the starting battery via solar panels if the service battery is fully charged
- Isolation of the starting battery and the service battery
- Temperature and voltage compensation features prolong battery life and improve system performance
- Features: battery isolation, over-voltage protection, battery temperature protection, over-current protection, overheat protection, reverse current protection, solar panel and alternator reverse polarity protection
- Compatible with multiple battery types: Sealed, AGM, GEL, Flooded, and Lithium

Nice combination solar + alternator in one package. If it had a 1000 watt inverter it would be perfect.

These are reasons I picked this (installed under sink in dry environment in the boat) for both my camper and boat. I eventually replaced all AGM house batteries with LiFePO4, Renogy (cheaper, lighter), in camper and BattleBorne in boat. So far, so good.

 

[smckean (Tosca)]

If you are running with the engine and battery switch is on house, then you are not charging that house battery.

Don't over look this very important point that Bob makes. You say your battery switch only has 2 positions: House & All (I will presume there is also an Off position). Unless that switch is in the All position, there is no way that current can flow into the house battery from the alternator. You say you normally have the switch in the House position while underway (note: the only time the alternator is producing current). This means you are getting zero charging of your house battery while underway. You also say that you rarely hook up to 120v AC when you store the boat or while you are at a marina. There must be something missing in your description because under these circumstances you house battery is basically never getting charged!

The best solution is to use a Automatic voltage Relay AVR or Voltage sensitive relay, VSR.

I agree with Bob here; but be aware VSR's (as opposed to battery isolators) draw a small current always (even while the boat is stored). Since you say you don't plug your boat into 120vAC power while storing it, this small draw may flatten your battery over several months of storage.

 

[BBlalock]

Well it is a 3 position switch - Off, 1 and ALL. Looks like I need to run with the switch at All and then when we get to a day destination move to 1, the fridge and VHF could still run while we are at play. Then back to All for the run home.
I'll see how my batteries act with this change in battery use.
I will not make any changes except for battery selection with the existing switch.
I really do appreciate all your inputs.
Benton :thup