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I have a switch on the bridge near the on /off engine switches its says parallel switch . what is that for and what does it do????
David R

It puts both your batteries in parallel, for starting the mains when you are low on juice.

I also just recently learned that with CAT 3208's, which have montrous starters, you can use the battery parallel switch to lessen the shock load on the batteries when starting the engines, and thus help them live longer. Not sure if that's true but it makes sense to me, so I plan to start doing that.

But I believe the original purpose is to get you started with near-dead batteries.

When I redid my B26, I re-installed a new solonoid and dash switch along with new wiring to mimick what Bertram did at the factory.

The Solonoid that they used and even my new one is only good for combining both batteries for 10 seconds at a time. It really works. I had my STB battery drain because the power wires for the pumps had slipped into the into bilge and got caught by the float switch. It drained one battery completely. I used the parallel switch to get that engine started and the battery has been fine ever since. Of course, I also fixed the wire ties.

My opinion, it's real easy to flick a switch on the dash rather then climb down and use and operate a 1-2-both type switch. It's also a lot safer then hauling around jumper cables.

Chiles

You say that your paralelling solenoid is only good for 10 sec at a time.. I have the same setup in a Bertram 33 and am wondering what happens if you exceed the 10 sec limit? Does the solenoid overheat? So far I have not had to use it, but since Bertram apparently installed it when the boat was built I replaced the solenoid when I rewired the boat recently.

When you replaced your solonoid, it should have come with some technical informaiton as to duty cycles ratings.

Somewhere in the paperwork I got with mine, I determined that duplicate of the original I replaced was not intended to be used for anything other then momentary starting situations. I guess that is the difference between a solonoid and a relay, where a relay is for 100% duty cycles and solonoids that I have worked with are used for things like starters.

Again, this was for mine, and I'm sure there are several kinds out there.

Chiles

Guy,

Never crank any engine for longer that 10 seconds and wait at least 10 seconds between cranks...

All of the wiring, solenoids, breakers & etc in the circuit are going to generate a lot of heat from the amperage & you run the risk of a melt down on the wires smaller than battery cables. Also hard on the starter, (& if you have older gas engines, the contact points).

10 seconds is a long time, when you think of it, & if an engine hasn't started within 3 ten second trys, something is wrong.

Br,

Patrick

Thanks both of you...

I agree that more than 10 sec cranking on a starter is a long time.. my Cummins 6Bs start almost before I can get my finger back off the button. I didn't get anything paperwork wise with the new relay.. I specified the usage and had someone else pick it up for me but he didn't get any documentation. I installed it with the same sized cables as my starting battery circuits, so I feel I am good as far as the cables handling the load, but I was concerned about creating a fire somewhere due to overheating.