Help, I need some piece of mind. I'm about to embarq on a cruise from St. Marks, Fl to down the West Coast of Florida to the Keys. Probably about 6 to 8 weeks. We have thoughts of even going on over to the Bahamas if all goes well and if we can fit it in before the Hurricane season. I'm worried about electrical consumption.
My question is: If I keep the battery switch on "HOUSE" while anchored out then discover that the house batteries are discharged to the point they won't start the engine, then I switch over to the "Engine" only battery and start the engine, how can I then go back and charge the house batteries? If I switch over while the engine is running, won't I likely fry the altenator diodes? I'm told that I should never move that battery switch while the engine is running. I realize that I'm a little "challenged" in this area. Any/all help appreciated as usual.
Thanks
Sam
Capt. Sam Murphy
1994 Catalina 36, Hull 1327
Shoal draft, two cabin model.
Panama City, Florida
On my battery switch the off points up, the battery 1 points left, the both points down, and the battery 2 points right.
The way I use the switch, my "house" battery is position 2 and my "engine" battery is position 1. When I am at anchor I use position 2. When I start the engine I use position 1. When I have the engine running I put the switch to both to charge both batteries.
Switching between 1, both, and 2 while the engine is running should not be a problem. Switching to off when the engine is running would definitely be a problem.
Marc Nachman
s/v Whispering Eye
2004 Catalina 36 Mk II #2201
s/v Whispering Eye
2004 Catalina 36 Mk II #2201
SRFM/WK/M35b
St. Petersburg, FL
Marc, I think you're over-complicating your life. What I do on High Flight is to *always*, 24/7/365, leave the switch on Battery #2, the house bank, which is the two paralleled 4Ds. The only time I would switch to Battery #1, my single back-up starting battery, is if I ran the house bank flat and couldn't start the engine from #2. I haven't had my battery switch on #1 for, oh, maybe 7 or 8 years.
Of course, the only time my Start #1 battery gets charged is when on shore power and I have the charger on. But then, there is never a load on #1, and it's always full voltage when I check it. I've replaced this battery once in the 10 year life of the boat. The present battery is about 4 years old; the original lasted 6 years.
Sam, I'm not an expert on this, so you should check the Calder or Wing book (or wait for a more authoritative posting on this forum), but I believe it is switching to OFF while the engine is running that presents to risk to the alternator. Once your engine is started you should be able to charge your house bank by selecting #2. Just don't switch through OFF. If #2 is flat it will take a LONG time to fully charge by engine, possibly less by charger.
Larry Brandt
S/V High Flight #2109
Pacific Northwest, PDX-based
2002 C-36 mkII SR/FK M35B
If your battery switch is "make before break" then you can switch on the fly. But if it's not you should not do it. The only way to know for sure is to look up the model number on the mfg's website and see what they say. As Larry says though, turning it off with the engine running regardless of what type of switch it is likely will toast your diodes.