Battery switch question

[dave_and_dd]

Hey 309 owners. Newbie here. Quick bio, I grew up as a sailor, owned powerboats the last 5 years, now returning to sailing several years before retirement. Also, pretty experienced with electrics and outboards, no diesel exp (yet).

Just now buying a 309-2007. Surveyed very well, looks to be very well maintained. Closing and picking it up next week.

Current owner has all manuals, but I don't have hands on them yet. Noticed during sailing trials, he puts battery switch on both. Says he doesn't know which setting is house vs engine.

-What's SOP for setting the switch during usage?

-Does alternator charge both batts? (Even if switch isn't in both?)

From running power boats with a dual starting battery, we never put it on both, except, when changing from 1 to 2, or in an emergency if low on power.

Thanks for any help, Dave S - Tamps, fl

 

[woodster]

congratulations on your new boat ......there is a lot of info on your questions on this site ...i would suggest you go to mainsails ...compass marine site and do a lot of reading on this subject ...there is no good answer at this time about your new boat electrical system ...because we don't know how it is set up ...but after you read all the info maine has shared you will understand why ...and then you will be able to trace your systems armed with the knowledge of what to look for and what you need ...and then you will be able to ask specific questions relating to your boat ...another one that will be good for answers here will be Stu Jackson ....good luck

 

[Stu Jackson]

Hi & welcome.

These should get you started:

OEM 1-2-B Switch Wiring History http://c34.org/bbs/index.php/topic,4949.msg30101.html#msg30101

Basic Battery Wiring Diagrams This is a very good basic primer for boat system wiring: http://c34.org/bbs/index.php/topic,6604.0.html

They come from this topic:

Electrical Systems 101 http://c34.org/bbs/index.php/topic,5977.0.html


This is another very good basic primer for boat system wiring: The 1-2-B Switch by Maine Sail (brings together a lot of what this subject is all about)
http://forums.catalina.sailboatowners.com/showthread.php?t=137615

 

[dave_and_dd]

Thanks so much Woody and Stu. Those refs provide a wealth of info and answer more questions than I had thought of.

Dave in Tampa

 

[Pompadi]

Hi Dave,

We always start engine with both batteries unless the house battery is very low,
both batteries are left on while engine is running and then switch to house battery when engine off.

I believe both have be to on to accept charge from alternator .

Battery 1 is our house battery, but the manual indicates 1 is the engine battery.
I've labelled the switch to stop confusion when crew are asked to switch from both to house.

We have 200ah house and 100ah engine battery, both are AGM

Great boat by the way, we've had very few problems

Steve

 

[dave_and_dd]

Hi Steve, thanks for the reply. I'll have to trace and find out specifically how mine is all hooked up.

Having read all the links above (and consistent with my current power boating experience), I plan to typically not start on both batteries. Doing so will mask a battery going bad. You won't know until it's too late.

after engine is started, if both need charging, switch to both (not through off!)

Or, I'll end up rewiring as per some of the suggestions in the links above....

Dave

 

[Crystal_RPAYC]

Hi Dave,
Catalina recommend staring in 1+2 as this charges both batteries. Then switch to house battery when motor turned off. You can get an indication of a failing battery by the rate of voltage fall off when batteries are not being used nor being charged. Battery management is a good extra.
My 309 had the same set up as Pompadi 1=House 200AH (2x100AHM), 2=Motor 100AH AGM and furthest from Switch Board so it would be a good idea to check the wiring.
I changed these around on the selector switch when I installed a solar panel and for the first time ever the green pilot light came on when on House battery only.

 

[Pompadi]

Crystal,
Just wondering what make/ model battery monitor you fitted
Steve

 

[Capt jgw]

You'll have to get into your writing and see how it's hooked up. The "correct" way, though never done at the factory, is to connect the alternator output direct to the house battery, and charge the start battery through a "battery combiner" or Echocharge (NOT an isolator diode) as Mainsail shows on his site. I've been running my boats that way for years, and it works great. The 1-2-both switch stays set to start on 1, and you never touch it again during normal operation. Running the engine on "both" is just too dangerous, both for switching through off and killing your alternator, or forgetting to switch back and draining your batteries.
If the PO doesn't know how it's set up, I'd assume its stock, with the alt output run to the starter lug. That's the easiest and cheapest way to install the engine, so most of the manufacturers do it that way. Sometimes they use the same size and type batteries for house and start, so it doesn't matter which is which.

 

[Crystal_RPAYC]

Crystal,
Just wondering what make/ model battery monitor you fitted
Steve

Hi Steve,
A VICTRON BATTERY SYSTEM MONITOR VOLT METER 12V 12 VOLT BMV-600S + NARVA 87630 purchased on eBay. See my recent post on flexible solar panel.

 

[jonelli]

Dave/Crystal,
I just changed all the battery cabling on my 30mkII from #4 to 1/0 size wire. I was not able to start my engine originally with only one battery (had to use both) which I was not happy with since if one battery gets low chances of starting again go down.
Now I can start perfectly off either battery. My batteries have 600CCA and my original wiring was dropping too much voltage.
I wired the alternator and AC charger directly to one battery and installed a battery combiner.
Now it doesn't matter if I'm switched to #1 or #2, both always are charging, and one is "main" and the other is "backup/reserve".

 

[Maine Sail]

Dave/Crystal,
I just changed all the battery cabling on my 30mkII from #4 to 1/0 size wire.

I was not able to start my engine originally with only one battery (had to use both)

Now I can start perfectly off either battery.

Yep... The right wire makes a difference....