Battery bank question

[ahumbug1]

I recently purchased a 1986 Catalina 34' slipped in San Diego West Marina. I know this is dumb but I don't know which bank is engine start 1 or 2 on the switch. Which is the house? I don't really know the condition of the batteries. They look good and water level is ok but I have to select all to start the engine. I would like feedback as I don't know much about the systems on my boat

Thanks!
Al
S/V St. Thomas

[ValiantV]

Hey Al,

I have a '92 C30 and bet the electrical system is similar if not identical to yours (at least as far as the basic 12v goes)

You designate which is "start" and "house" by using the 1-2-both battery switch. Whatever position the switch is in, that's what used for whatever your doing *now*.

Typical practice is to sail on 1 or 2 and save the other to start. That way, you don't kill both batteries and have no juice to crank the engine.

As for which is which, a helpful previous owner marked them. I haven't checked to see if he got it right - but since both of our batteries are new, it really doesn't matter.

To discover which is which, remove and insulate one if the positive batter cables and use a voltmeter (or a cabin light) to see which switch position is live and which is dead. The position that turns your light on or registers ~12 volts is the number of the connected battery.

V

[ValiantV]

BTW, if it only starts on "both" one of them is dead or both are weak.

Look for date codes on the batteries. They're typically only good for a couple of years - maybe 5 if they're babied. Mistreatment in the past will have shortened their lifespan even if they're "young".

[accomplice]

If you need to select "Both" to start then at least one of your batteries is dead.

If you look at the batteries, probably one is a deep cycle battery and one is a starting battery. If you disconnect one of the terminals (I suggest ground) on one of the batteries, you can then use the selector switch and any electrical device (interior lighting?) to see which battery is #1 and which is #2.

If you have a voltmeter, I suggest you check the voltage with no load and the voltage of each battery separately when used to start the boat. Either battery alone should be able to start the engine.

If the boat is at a slip, is it connected to shore power? Does it have a battery charger? Two bank? What does it report about the charging status of each bank?

[ValiantV]

Another PS -

When replacing my batteries, I found the last people who worked on them did a terrible job of crimping on the terminals. They were all loose enough to pull off the end if the cable with your fingers. A miracle it started at all and didn't overheat the connections.

It's possible you have that or a related problem between the battery, main battery switch, and/ or starter.

Time to get a multimeter if you don't already have one. A good book on boat maintenance would also be a great investment. Look for Don Casey's sailboat Maintenance book. It's very comprehensive.

[ValiantV]

Originally Posted by accomplice

If you need to select "Both" to start then at least one of your batteries is dead.

If you look at the batteries, probably one is a deep cycle battery and one is a starting battery. If you disconnect one of the terminals (I suggest ground) on one of the batteries, you can then use the selector switch and any electrical device (interior lighting?) to see which battery is #1 and which is #2.

If you have a voltmeter, I suggest you check the voltage with no load and the voltage of each battery separately when used to start the boat. Either battery alone should be able to start the engine.

If the boat is at a slip, is it connected to shore power? Does it have a battery charger? Two bank? What does it report about the charging status of each bank?

If the '86 Catalina is anything like the '92, the ground is common for both batteries with the common going to one battery and a "jumper" going from that battery to the other.

Are people still using "specialized" starting vs deep-cycle batteries for coastal cruisers? I'm using "marine/RV hybrid" batteries and that's what the PO did as well. With such tiny engines, a real cranking battery really isn't needed.

[Stu Jackson]

Many of your questions are answered here:

Electrical Systems 101 Electrical Systems 101

To figure out what switch position works, turn a light on and move the switch.

You're very welcome to join us at the C34 forum as well as here, too.

Good luck.

[S/V Illusion]

Frankly, there is no definitive answer to your question because there is no way anyone here can determine what, if anything, a previous owner did. Given the boat is 15 years old, it's a certainty things have been replaced, likely changed and possibly 'screwed with' by someone to change the original design.

[ahumbug1]

Originally Posted by Stu Jackson

Many of your questions are answered here:

Electrical Systems 101 Electrical Systems 101

To figure out what switch position works, turn a light on and move the switch.

You're very welcome to join us at the C34 forum as well as here, too.

Good luck.

I have three batteries. Can I tell which is house by looking at the wiring? Thanks for the info on the C34 forum. How do I find it? I am not good on computers!

AL

[ValiantV]

Originally Posted by ahumbug1

I have three batteries. Can I tell which is house by looking at the wiring? Thanks for the info on the C34 forum. How do I find it? I am not good on computers!

AL

Dunno if the C34 comes with 3 batteries from the factory or if it is a modification. Does your main battery selector have positions for 2 batteries, 3 batteries, or perhaps there is a second selector - which is ONE way that C30 owners do to add a battery.

Sometimes, owners add a third battery in parallel with one of the two typical batteries. You'd have to trace the wiring to be certain.

This is a situation where photos might help people give you more informed advice.

Also - finding a more experienced owner who is a dock neighbor to take a look for you. Just remember, even "professionals" get it wrong sometime.

Have fun exploring your "new" boat. I know I am.

[Stu Jackson]

Originally Posted by ahumbug1

I have three batteries. Can I tell which is house by looking at the wiring? Thanks for the info on the C34 forum. How do I find it? I am not good on computers!

AL

Al, just click on the link.