Battery question

[agprice22]

I have two deep cycle batteries in a house bank being charged through shore power and an inverter/charger. I have an 9.9 hp outboard with an alternator.
If I use this house bank to start the motor, can I allow the motor to charge the house bank while the batteries are also connected to the charger?
I am interested in starting the outboard with the house bank, so I don't have to keep a dedicated starter battery.
Do I need to isolate the alternator from the charger? If so, what would I use to connect both the charger and alternator to the batteries? While at the dock, the charger could supply charge while the motor is running and charging too, so the two would conflict.


Thanks,
Andrew

 

[woodster]

just turn off the charger when you start the motor ...because you are going to unhook the shore power any way...i always turn my charger off when using the engine ...not sure that is required but it can't hurt

 

[agprice22]

Haha! The simplest solution!
Thanks!

 

[Benny17441]

No harm should come to either the charger or the alternator for running them simultaneously as long as both units are in good working order. I have been doing that for years and many others do the same with no reported incidents. The only thing I would be concerned about would be redundancy or maintaining emergency backup power to start the engine. Depending on how the house batteries may be wired they could behave as a single battery perhaps unable to back itself up. A solution is at hand by using a battery switch that would allow isolating or combining the batteries as needed. Some also carry an automotive type battery pack aboard to provide starter power in an emergency.

 

[Ron20324]

[QUOTE... i always turn my charger off when using the engine ...not sure that is required but it can't hurt[/QUOTE]

My Beneteau manual for the Yanmar says to not run the engine when the charger is putting out. I see the reasoning, but others disagree.