how the 3rd battery

[freddy063]

What am I missing here, for years I hook up my three battery, 1 port, 1 starboard, and 1 house. There a wire that connects the motor to the battery's that charge them.(port and starboard battery's )How does the house battery get charged when the motors are running?

 

[ocnslr]

Do you have a Yamaha engine?

Most Yamaha models have an auxiliary charging connection. You need the Yamaha adapter to connect it to a battery. Connect it to the house battery and it will charge it separately from whichever battery the main engine lead is connected to at that time.

Our twins each charge their own starting battery, and both have their auxiliary charging lead connected to the "house bank", which is two batteries in parallel.

Brian

 

[freddy063]

so the little wire is the aux charge and not the main charging wire, yes, Yamaha's , so I should put both little wires on the house battery?
Thanks Brian

the trouble I'm having is as I get older I forget how I do things year after year on something you only do once a year, when I first got the boat I marked all the battery cables with blue electrical tape, one stripe on battery one , two on battery, etc, and green tape on all the grounds cable in the same matter . but I over think things sometime and think I have to fix something that isn't broken.

 

[ocnslr]

The heavy cable to the engine that carries the high current for the starting motor also serves to charge the battery.

If you have a non-connected smaller wire you can check it before connecting to the house battery. Measure the voltage from the connector to ground with the engine off, then with the engine running. Should be zero when off, then approx 13-14 volts when engine idling. This should serve to verify that the connector you are testing is indeed the auxiliary charging lead.

Brian

 

[fish_hunter]

How do you charge the house battery if you dont have Yamahas? I have twin 250 Optimax's and they dont have an aux charging lead, or so I was told by my mechanic.
currently, I have two blue top optima batteries (1000 cca each) in parallel connected to the stbd engine and one interstate deep cycle as my other bank connected to my port engine. each bank has a switch so i can start either engine on either battery. the previous owner told me he always ran both switches in the "both" position. that makes me nervous. I have been 20 miles offshore with a dead battery (fishfinder, electrical reels, radio going while drifting for halibut), luckily my kicker motor had an alternator and once i pull started it, it charged the batteries enough to start the main engine. not a good feeling...
Personnaly, i think I should have 3 battery banks. a blue top to each engine and then the deep cycle battery on its own. but how do you charge the house battery in this configuration?

thanks,
Fish_hunter

 

[onoahimahi]

I just looked at the electrical diagram for the 1998 Sailfish 272 and it shows the charging connections for Yamaha, Mercury and OMC. It appears that different isolators are used for each engine manufacturer.

 

[Legend]

Mine Sailfish has two wires running to two batteries - one battery charges alone and there are two batteries that are linked together and the second charging wire takes care of both of them -

 

[fish_hunter]

I figured out some of my issues while halibut fishing this weekend. With 3 electric reels and all the house loads running off the stbd bank (2 blue optima's) and basically nothing running off the port bank (1 interstate deep cycle) my stbd bank was too drained to start the engine. It seems to me that the batteries are backwards, in that the house loads should run off the deep cycle and not the two optima starting batteries. I think I should move the deep cycle and buy another deep cycle and mount them in the stbd battery locker and then move one of the optima's to the port locker. That would have the optima starting port engine only and the two deep cycles starting the stbd engine and providing house loads. Comments?