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SpcAlan1 09-04-2009 10:47 AM

Rewiring my Catalina 25
First off.. I know nothing about electrical systems.

Right now I have 1 marina battery that is being fed by a Coleman Solar Panel. Which runs the cabin lights, running lights, and a 12v cigarette plug.

I would like to add a gauge to see what my battery's juice level is, and I want to know what the load is currently.

What gauges should I buy and how would they work?

SpcAlan1 09-04-2009 10:49 AM

Currently I have the standard catalina "toggle switch" panel, which has master, cabin, running, spreaders, toggle switches, which I would like to move from behind the sink.

floatsome 09-07-2009 05:54 AM


Originally Posted by SpcAlan1 (Post 519882)
First off.. I know nothing about electrical systems.

That's the first step: systematically learning about marine electrical systems, using your boat's current setup and likely use as a model to orient you to all this new information.

As part of this first step, draw a schematic of your boat's wiring, and draw up an inventory of everything: wire sizes, appliance make and model, fuses, etc.

Before re-wiring, learn how to select marine grade wire, pick the right wire sizes, make proper connections, and run wire properly on a boat. Check out the AYBC standards.

Suggestion: Nigel Calder's Boatowner's Mechanical and Electrical Manual and Wing's Boatowner's Illustrated Electrical Handbook. And take a marine electronics or marine maintenance course from eg USPS or CPS.


Originally Posted by SpcAlan1 (Post 519882)
What gauges should I buy and how would they work?

If your system is as simple as you describe, you might start with a 12 volt voltmeter. A fully charged battery is about 12.6 volts after any charger and appliance attached to it has been turned off long enough for it to settle to its resting charge state. With a charger of some kind attached and operating, the voltage will be a little higher than that. Resting voltages lower than 12.6 volts generally indicated some state of discharge, if the measurement is accurate (good gauge, good wire connections, etc).

12.6+ 100%
12.5 90%
12.3 70%
12.1 50% (Warning!)
11.9 40%
10.5 0% (dead battery)

Note: these are approximate numbers. Actual charge states and significance vary with type of battery, temperature and other factors.

AdamLein 09-07-2009 01:31 PM


Originally Posted by floatsome (Post 520358)
Suggestion: Nigel Calder's Boatowner's Mechanical and Electrical Manual

I second this recommendation. Good both on a practical level and a theoretical one, in that it will help you to really understand what's going on.

SpcAlan1 09-07-2009 03:22 PM

I took my battery back to Walmart. They checked it and it was reading 0 volts, and only 12 amps ( on a 600 amp battery ). So they said it was dead.
I exchanged it and went back to boat, where I found out that the previous owner did a shoddy wiring job of the soar charger, and the wires were completely dissconnected under the floor betwwen the hull and the wood floor.
That leads me to believe that the reason my lights were getting dimmer by the day ( when I used them ). was because I was using the battery with no charging going on.

So I fixed the wiring, taped up everything very nicely and checked the solar charger, and now evertything is on working order. Woohhooo.

We went sailing today in light winds and had a great time.

mitiempo 09-07-2009 05:32 PM

Glad you got it sorted out. No wires on a boat should ever be taped. A good crimp connector (or a soldered connection) is all that should be used. A good purchase is a cheap digital multimeter - about 12-15 bucks. It will be a big help if there is ever an issue with connections. 600 amp battery? don't think that's right.

SpcAlan1 09-07-2009 07:41 PM

it was a Marine Max from Walmart - 600 coldcranking amps

AdamLein 09-07-2009 08:05 PM

The suggestion battery at 0 volts is pretty astonishing. I've also never heard of anybody doing a test to measure cold cranking amps but I guess it's possible... did they put the batter in a freezer overnight and then bridge the terminals with an ammeter?

mitiempo 09-07-2009 08:30 PM

If it was showing 0 volts, how could they measure 12 amps? You can test a battery to see if it's good, but you can't measure capacity easily - hence Link type products. And I know of no test for cold cranking amps other than a lab at say, Trojan Batteries.

SpcAlan1 09-08-2009 08:15 AM

I can only go by what Walmart told me.

Either way, i got a replacement battery.

Saved $ 75 bucks.

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