Battery Switch Location and Emergencies

What does Rick know? He has only been making this business his life for the past "many" decades.

But having said this Gonzo, I have recently been on several high end yachts who each treat this subject a little differently, much to the*builder's nightmares*and 2nd and 3rd owner's confusion . It seems* many novice "electrical" engineer/owners from the computer industry* made their demands*on*the builders. One off charging/starting circuit designed vessels are now being retrofitted to the old standards. I toured one vessel with the*boat builder who said the best way to sort out the high tech computer controlled mess was to toss out the inverter charging*system and go back to the basics.

Bottom line, the marine environment is a bit different than shore based systems. Being an electrical guy, you know this.


-- Edited by sunchaser on Friday 23rd of December 2011 09:30:10 AM

GonzoF1 wrote:
TBH, I have never heard about it either, but on Rick's recommendation, I will probably be adding a 400A slo-blo into the starting circuit of my upcoming electrical upgrade project.

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Whoa!

Gonzo, go back and look at that drawing I sent you, there is no fuse on the starting circuit and there never was. Your latest drawing does not include one either. There is one on the house battery before the DC buss that is sized to handle all projected DC loads.

My comments regarding the capacity of a fuse to handle starting current was a response to someone who could not believe that a fuse could handle that current. It was not a suggestion to install one, nor was it a suggetion that it was something I would do. The result of doing so was clearly shown by P/F's experience and my comments are very clear about the risk of such an installation.

You guys had better start reading for content and checking quotes before you post what you think I said. I am not going to allow my comments or suggestions to be so badly misrepresented on this type of subject.

You need to learn that when a question is asked, the answer does not automatically imply that the practice is good, bad, or indifferent.

Someone questioned how a fuse could handle starting current yet effectively protect wiring. I answered that question by explaining how it can allow starting then explained how it could protect the wire against the most likely fault. That does not mean I would install a fuse, I don't have one on my boat, and don't plan to install one or suggest anyone else install one.

Nobody asked if it was a good idea. If they had I might have posted my opinion on such things, but as a rule, I don't answer questions that have not been asked.


-- Edited by RickB on Friday 23rd of December 2011 10:34:54 AM

Let me see if I can summarize some of the points above to get this back to my neophyte level. This has been a most informative journey.

1. There seems to be (my interpretation) a good case for installing "battery disconnect" switches. Looks like these are placed as close as possible (minimum or no cable run) to the battery(s).

2. skipperdude has a three "on-off" switch setup that seems (to me) to be the height of simplicity.

Does this mean that, if I went back to square one, I could junk the existing O12A switches (one for house, one for start), install two On-Offs as battery disconnects, and a third On-Off to parallel, and call it a day?

Additionally, as I followed this thread, I have looked at the myriad switch offerings on line. Can anyone point me to a good resource for figuring out the specs for such switches? Second, (and knowing that the particular requirements for any given application may vary the answer) are there any good manufacturers or vendors that I should be looking at for these components? Given the wide variance in pricing for what seems to be the same switch component, I have to believe there are significant quality issues in manufacture.

Again, I'm very greatful for the input.

And, by the way, Merry Christmas and/or Happy Hanukkah (both appropriate in my family) and a Happy New Year!

I probably know more about electricity than some might think I do. I was employed in the field for most of my career.

Of course a fuse could be sized to handle the current draw of the starter, but at that point, it doesn't really accomplish much. Remember, you would have to account for the increased current draw for starting a very cold engine with thickened oil. And the ability to crank the engine for several seconds. The ABYC does not require overcurrent protection in the starting circuit for that reason. Their expertise is good enough for me.

At some point, the internal resistance of the battery and the resistance of the cables and the accidental short limit the current that can flow.

sbu22 wrote:
................. Does this mean that, if I went back to square one, I could junk the existing O12A switches (one for house, one for start), install two On-Offs as battery disconnects, and a third On-Off to parallel, and call it a day?

At some point, you might want to be able to start the engine with the house battery only (and the starting battery out of the circuit because it is dead or has a shorted cell).* Just keep this in mind when designing your electrical system.

Click to expand...

*

sbu22 wrote:
Does this mean that, if I went back to square one, I could ... install two On-Offs as battery disconnects, and a third On-Off to parallel, and call it a day?

Click to expand...

*In a word, yes.

Here's how I did it.*

I changed the Start On/Off switch to a O-1-A-2 switch to allow me to start the engines with the start bank only (normal), the house bank only or both.* I can also isolate all batteries from the starters with the OFF position in the event of a starter stuck*ON or bendix engaged.




-- Edited by FlyWright on Friday 23rd of December 2011 04:04:55 PM

Ooops.... My bad. I read my schematic wrong. SORRY!!! Please resume.

IF someone really slept better with a huge fuse in the battery circuit , it would be no operational danger.

Just use a 1-2 both switch to by pass the blown fuse , if it ever happens.

OF course fixing the fault before switching might be desired.

And if it should blow with an alternator operating , carry spare diodes , or a diode board.

Appreciate the schematic, Al. Makes me think I should do some more tracing before I get too far ahead of myself. A good New years weekend project!

FF wrote:
IF someone really slept better with a huge fuse in the battery circuit , it would be no operational danger.

Just use a 1-2 both switch to by pass the blown fuse , if it ever happens.

OF course fixing the fault before switching might be desired.

A simple On/OFF would bypass the fuse.* I think the point is (and why ABYC does not require a fuse) is that the fuse would have to be rated very close to the maximum current that the battery could produce to avoid "nuisance" blowing.

Any fuse and any switch would have to be located very near the battery and might be difficult to get to in an emergency.

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*

We have a stand up walk around engine room so getting to the battery/fuse is not difficult. I have extra fuses next to the fuse box/link.* 10+ years and not a problem, but then again I know not to get air in the fuel line and/or do not crank and crank and crank and crank the engine.* If it does not start in 5 seconds something is wrong.
*
The alternative to the fuse was to replace the 30+ year old wire.* The fuse cost 50 bucks, and took less then 5 minutes vs. the new battery cable/wire would have cost 1+ boat unit and several hours.* When your boat gets to be 30+ years old and there are only a couple of insurance companies that will insure, you may have a different view point.**

When we acquired our Californian 34 we were absolutely clueless about power boat systems. Our first learning experience involving fire/electrical stuff came while working on the boat at the dock. While checking the fuel gauge reading on the port side the start up warning horn shorted & smoked, the port ignition switch caught fire, melted & shorted out, that led to the port engine starting on its own. In a word: chaos. Fortunately, the battery switches are located under the settee (start side O1A2) & under the galley sink(House On/Off). Killing the DC power put the fire out in the lower station panel. Diving into the engine room, turning off the fuel @ the tank & hitting the manual shutdown lever shut down the engine. Our wiring is similar to Flywright's. I'm glad the disconnect was easily available. We also spend a lot more time on checking connections & wire conditions.

I'm glad the disconnect was easily available.

Nice , but most alternators will need new diodes if they are shut off while charging.

A fire would be worth a new alt, even tho it might not be part of the problem.

Willy wrote:
Battery disconnects located*in the ER space can be a real PITA !

The engine room would indeed be a poor*location for battery disconnects.

You have to hope and expect that boat manufacturers would think of these things when they design the boats so owners wouldn't have to change things later.

*

BTW: I need electrical power to shut off my (diesel) engine.* I expect at least a few others are the same.

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*



-- Edited by rwidman on Tuesday 3rd of January 2012 06:34:00 AM



-- Edited by rwidman on Tuesday 3rd of January 2012 06:40:17 AM


-- Edited by rwidman on Tuesday 3rd of January 2012 03:14:02 PM

Could you rig a switch on the fuel solenoid. If there is one on your engine. All I need to do is disconnect mine. I have it rigged with a bayonett style wire attachment. When disconnected it shuts off the fuel supply.

SD

skipperdude wrote:
Could you rig a switch on the fuel solenoid. If there is one on your engine. All I need to do is disconnect mine. I have it rigged with a bayonett style wire attachment. When disconnected it shuts off the fuel supply.

SD

I beleieve the way mine is designed, the fuel supply is open unless the solenoid is engaged* It's a "kill" solenoid.

It's a Volvo TAMD 41P

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*

T handles and cable can be used to stop most non electronic injection diesels.

The instant reset allows the engine to start easily , shutting off the fuel can be a second problem.

Most folks do not have either the gear or a gravity day tank to make bleeding a snap.

Always best not to start a SNOWBALL of problems.

Willy - good thought. The Blue Sea remotes I've seen are solenoid operated. I don't know the details of operation. But, using an electrically operated device to combat an electrical casualty seems a bit counter-intuitive. Maybe as others have commented, a sturdy knife switch with a mechanical, remote, operator would be simple and have merit. Anyone seen a setup like that or know where to buy one ? I've been through a bunch of on-line sources and not seen anything with the amp ratings discussed above, much less with a remote, mechanical, operator.

I had an issue with a non-operating port shutdown solenoid. To get around the problem until I got back home, I ran a poly cord from the shutdown bellcrank to the forward ER door. When I needed to shut down, I just pulled the cord until the engine dies. The spring pressure was sufficient to return the bellcrank to the 'run' position. Yes, it was funky, but it got me home.

I have considered adding these to provide an emergency mechanical shutdown system. It's just way down on my list of gotta-haves.

My problem turned out to be a bad wire to the solenoid, but I didn't find that until I replaced the solenoid and still had an intermittent problem. After replacing the wire, all is well and now I have a spare solenoid.

I haven't been able to determine exactly where my shut down solenoid is. I'm going to need someone at the switch and me in the bilge. With the engine off!

My backup plan is to block the air intake.

That cable looks like a good emergency shut down if there's a way to fit it.


-- Edited by rwidman on Wednesday 4th of January 2012 05:50:53 PM

FlyWright,

That is exactly the shut down method for my old Perkins6-354. Simple and reliable.

My battery shutdown is to the lower left of the lower helm.

Rob

37' Sedan


-- Edited by Datenight on Wednesday 4th of January 2012 07:50:05 PM

Hey Bob,

Got pics of that Sung Yung Sedan? Would love to see what it looks like.

Both my current and past boats have manual engine shutdowns, and I think they are a good idea.

You can also use for oil pre-lube by manually stopping the engine, and trying to start it.* Yeh, a little starter wear, but it only takes 10-15 seconds of starter work to*pre-lube.* OK if pre-lubing is an uncommon event.

"Anyone seen a setup like that or know where to buy one ?"

Any bus junk yard will have what you need . Some are single pole , others double.

It takes a strong pull to disconnect so I fear the reset would have to be manual.

Al,

I do have some nice pictures but have not been brave enough to go through the learning curve to post them. Looks like now is the time to get to work.

Rob

37' Sedan

The easy way:

Click in the quick reply box below, then select the Advance Editor button.* check the Attach Image(s) box to open a cell of boxes allowing you to browse, click to choose and attach multiple pics.

*

The other way:

Upload your photos to a web hosting site like Photobucket, copy the html code and paste it into the body of your post.

Now quit reading posts and get those pics posted!!

O.K. FlyWright here goes. If this works, these are the shots from us anchored in Quissett Harbor, Falmouth Cape Cod this summer. The interior shots were at the same time.

Rob

37' Sedan

Great. Now that wasn't so hard, was it..?