Battery Switch Location and Emergencies

[sbu22]

In the event of an electrical fire while underway, it would seem prudent to deenergize all 12 volt systems (in my case) until the problem can be isolated and cured - both as a damage control measure as well as attempting to contain damage to the electrical system.* However, the way my Viking (I know, not a trawler - but there are a lot of sharp people on this board that I haven't found anywhere else) is set up, this entails dropping into the engine room, squeezing my chubby body between two red hot engines, and getting to the rear (most distant) bulkhead where the battery switches are mounted.* Oh yeah, did I mention the fire?

The cure would seem to be to relocate the switches topside with the attendant monster gage cable runs or to go with "remote" battery switches.* I've only found one remote battery switch setup by Blue Seas ($$$).* Anyone have any experience doing the relocation?* I've not seen it - maybe I'm conjouring a low probability problem that doesn't* concern the experienced hands.* Any thoughts appreciated.

 

[bobofthenorth]

If you relocate the switches, unless you also relocate the batteries you will then have a long run of cable that can't be de-energized.* That's an increased risk in my estimation.*

Any chance to access the switch by some alternate method from the other side of the bulkhead perhaps?

*

 

[Edelweiss]

sbu22 wrote:
*I've not seen it - maybe I'm conjouring a low probability problem that doesn't* concern the experienced hands.* Any thoughts appreciated.

*No, I think you are right.* Electrical fires are a real concern and having your battery switch on the rear bulk head inside the engine room is not a good situation.**Mine*would be the same*setup except the manufacture placed*the battery switch*on the other side of that bulkhead in the aft cabin closet.* If possible, you should relocate your switch as well.

Larry B

 

[markpierce]

William, I have master switches in the engine room (not accessible without opening a floor hatch) while switches for individual batteries are directly above in the pilothouse.* Are you talking about the master switch?

 

[dvd]

I agree that it would be best to have the switches readily available outside the ER. My house bank switch is on the electrical panel (main cabin), but I'm in the process of moving my genset start battery and engine start battery switches into the main cabin, or at least to lockers accessed easily from the main cabin. The new positions were selected with the existing cable length in mind. I'm able to reposition them just outside the ER but using the existing cables.

dvd

 

[FF]

Very few switches have the ability to pass the amperage of starting a LARGE diesel.

What might work for a car or tractor marinization may not work for a large diesel engine.

The only switches I have found that will do this are used in the coach (bifgbus) industry.

These are large and heavy but easy enough to hook a pull rod or cable to for an EMERGENCT DISCONECT.

The USCG requires a remote fuel shut off on any boat that is licensed to carry more than 6 victims.

This might be a great idea for cruisers , located outside the engine room it would stop boat theft as well as have a possible safety use.

 

[psneeld]

I tend to agree with bobofthenorth...what are the typical sources of 12 V fire in the engine room??* My guess is a chaffed, loose or melted wire on the engine (usually no big deal) or the starter remains engaged and smokes the bendix.* For that, a short run to the starter with a simple on/off switch located next to the battery should be fine as long as it's not inaccessable.

In a perfect world.*all cable*runs would be short and have switches out of the engine room.* Unfortunately long runs to good switch placement increases the chances of fire BECAUSE they are long runs...

A perko heavy duty switch is good up to 1200 amps for starting



-- Edited by psneeld on Saturday 17th of December 2011 06:49:20 AM


-- Edited by psneeld on Saturday 17th of December 2011 06:55:23 AM

 

[Jay N]

During 2009, all 12VDC and most 120VAC systems were rewired.* In running new primary 12VDC wiring, it was possible to position the start battery switch outside the engine room, but not the house bank switch.* The best compromise with ABYC E11 guidelines positioned the master switch for the house bank just under the shaft ally hatch.* While we don't need to get into the engine compartment to reach it, lifting the hatch is probably not the preferred action if there is an engine room fire.

That is one reason why I placed several hi-temp sensors in the engine room space connected to an alarm system, so that we can get early indication of any hot stuff.* Put another one behind the circuit breaker panel.

These sensors (Aqualarm #204 NO) will close on rising temperature at 135F, long before the two automatic extinguishers go off at 175F.

Also, in reviewing the specs on*a number of*different battery*switches, ended up going with Blue Seas Series 3000 switches.* There were the best of the bunch at the time of my review in 2008:* 2750 cranking amps, 600 continuous amps, and probably the best chance of actually breaking the circuit at those ratings.

 

[FlyWright]

I had the same concerns after reading of a starter engaging when the owners were on the dock. A fried starter caused smoke and fire damage and couldn't be easily disconnected with the switches in the ER.

My boat was set up with just one off-1 all-2 switch located in the galley which required a long cable run from the batteries near for fwd ER door. I also didn't like that the alternator charge ran via small wire to the starter cables, then through the switch and then to the batteries.

When I rewired last spring, I was able to locate separate switches for the house and start loads forward of the fwd ER door near the steps with much shorter cable run. With proper fusing on the house loads, it seems to me that the start circuit presents the greatest risk. If you can relocate that switch to outside the ER, you will have improved the safety of your boat. Just don't skimp on the switches or cable.

 

[FF]

or the starter remains engaged and smokes the bendix.

It is NOT the Bendix most folks worry about , a starter motor is DC and any DC motor that is turned becomes a DC generator.

Starters are very highly geared ,, Idle would be large starter RPM, so very high voltage in the entire electrical system.

Most bulbs don't like 100v , although some of today's toys are fairly immune .

Folks with electric controls and injection would loose the most.

On cars , when you engage the starter ,the radio, and many other items are cut off , no just for the load.

 

[sbu22]

Like FlyWright, I've got a simple O1A2 setup. What I'm envisioning is something along the lines of Mark's Coot setup (very nice, BTW). After reflection, I think the concept of extended cable runs probably does invite more potential problems than it solves. As usual, y'all have sent me to the "books" with a new perspective.

Jay - you must be up north. Down here on the Gulf in the summer, with 90-95 air temp and 80-85 water temp, I think I'd have 135F engine room temp alarms continuously while underway. Never measured, but I'm guessing ....

Appreciate the help with this.

 

[Jay N]

sbu22 wrote:
Jay - you must be up north. Down here on the Gulf in the summer, with 90-95 air temp and 80-85 water temp, I think I'd have 135F engine room temp alarms continuously while underway. Never measured, but I'm guessing ....

Yep, up north.

Max temps in PNW can be 90-95F air temp, but only 60-65F water temp.*

Normal summer temps are:* 70-80F air, and 55-60F water.

Normal winter temps are:* 35-45F air, 45-50F water.

Most I've seen in the engine compartment is 120F, usually around 110F for sustained runs.

Pick up a digital garden thermometer that will record max/min temps, it is a cheap tool for the engine compartment.


-- Edited by Jay N on Sunday 18th of December 2011 12:34:35 PM

 

[Conrad]

We have 2 8D's for house and 2 Group 27's for start; the master (Perko) switch is located in a locker at the aft end of the saloon and directly above the battery banks, which is close to ideal I think. Easy to access for emergencies, but also easy to access when switching between the banks, which is part of the routine depending on whether the engine is being started, sitting at anchor, or charging the batteries.*

The only improvement I can think of for our application would be to have the master switch out in the open to provide instant verification of the *position of the switch.

Last summer a book was inadvertently placed on a horizontally mounted cigarette lighter which of course soon resulted in a fire. Because the master switch was easily accessed, the power was cut and the fire doused.*

A secondary learning, of course, is to not have horizontally mounted cigarette lighters.

 

[bobofthenorth]

We had an electrical fire on a fifth wheel several years ago now so I'm very familiar with how powerful DC voltage can be.* I like FF's suggestion of knife-type bus disconnects - in fact I have a couple of them on our bus.* I can easily see how they could be set up as a catastrophic disconnect directly connected to the battery bank with a simple remote cable de-activation.* I think I might do exactly that on Gray Hawk this winter.

 

[millennium]

Blue seas remote battery switch. I can shut off all DC sources from this panel:

 

[bobofthenorth]

millennium wrote:
Blue seas remote battery switch. I can shut off all DC sources from this panel:

Don't bet your boat on it.* It was a remote battery switch failure that set my fifth wheel on fire.

 

[FF]

"Blue seas remote battery switch. I can shut off all DC sources from this panel:"

During normal operation, good luck when a shorted batt bank is pumping 2000 to 5000A to a short.

Only a class T fuse ir knife switch has a chance.

 

[rwidman]

bobofthenorth wrote:
If you relocate the switches, unless you also relocate the batteries you will then have a long run of cable that can't be de-energized.* That's an increased risk in my estimation.*

If it's the "house circuit", it should have a fuse or circuit breaker at the batteries so that's not a serious problem.

The engine starting circuit is not protected and I agree with you, this would be an increased risk.

Depending on the wiring layout of the boat, it might be possible to install an additional disconnect switch in the house wiring that's more accessible.

But - if the boat is wired properly and properly maintained, there should be little risk of an electrical fire that doesn't activate the existing overcurrent protection.

*

 

[Phil Fill]

We are required by the insurance company to install fuses on the house and start batteries, instead of changing the location of the switches on the house and start batteries.
*
True story.
*

The first week we owned the Eagle I learned the hard way.* Being a newbie, I know nothing about diesels, so when changing the filters I got air in the lines.* The engine started died as so got out of the marina.* So I cranked, and crank and crank until the fuse blew.* No knowing the boat, I did no know where the fuse was.* The wind was blowing us south down the lake straight for the SEATTLE POLICE dock.* Yep, we floated straight up against their dock, just like it as planned with 4 police standing on the dock ready to greet us!* Any way they had their mechanic bleed the engine, find the blown fuse, and get us OFF THEIR DOCK!* That was the first of several encounters with the Seattle police.***

*

*

*


-- Edited by Phil Fill on Monday 19th of December 2011 04:08:44 PM

 

[RickB]

Phil Fill wrote:*The wind was blowing use south down the lack straight for the SEATTLE POLICE dock.**

*

It sounds like it took out the compass too.

*

 

[rwidman]

Phil Fill wrote:We are required by the insurance company to install fuses on the house and start batteries, instead of changing the location of the switches on the house and start batteries. .......
*
How can you fuse the starting battery?* Any fuse large enough to pass the current required to start the engine would do little or nothing to protect the cables or battery.
*
ABYC does not require circuit protection for the starting circuit for this very reason.

*

 

[RickB]

rwidman wrote:*How can you fuse the starting battery?* Any fuse large enough to pass the current required to start the engine would do little or nothing to protect the cables or battery.
P/F's insurance company seems to have unusual powers.

You can fuse a starting battery though. As P/F explained, his worked until it got tired of the abuse and called it quits.

An ANL fuse rated for 500A can withstand more than 1000 for a second or two and that covers the duration of the high inrush current. Once cranking occurs the current drops off dramatically.

The condition for which you might install a fuse at the battery is a dead short between the cable and ground, such as could occur if the cable broke off the solenoid and contacted the block or a screwdrive somehow welded itself in that area. That would open the fuse very quickly and stop the cable from turning the engine room into a toaster oven.

*

 

[Phil Fill]

I was going to check the amp of the fuss last night but forgot. I think its 450 or 600 amps.* Being the Eagle is*33 years old, there are only a few insurance company will insure.* So when the insurance company recommends something should be done, I do it.* On the plus side, I have call the insurance auditor several times with questions.* Very freindly and helpful.**

*

*

*

*

 

[skipperdude]

I have 3 battery switches on the boat all three are. Off. On.

I never liked the 1, 2, Both set up. To many things to wory about or chances for a mistake. Like leaving it on both and not having power to start because you used the blender making to many Margaritas.

I use 2 8D batteries. One is house the other is start

The first switch is for the start battery only. It is either Off or On. Always on when I am on the boat

The second switch is for the house bank. It is either Off or On. Always on when I am On the boat.

The third switch is to combine the two banks it is always Off or ON*if I ever need both banks.

I like things simple.

SD

 

[RickB]

skipperdude wrote:I like things simple.

*I like your approach. Simple, reliable as long as the switches are good quality, and virtually bulletproof.

 

[skipperdude]

Gotcha there. I recently had one go out and there are a boat load of switches and manufacturers.

I now carry a spare and bought the best one*I could find. Not cheep.

SD

 

[FF]

I recently had one go out and there are a boat load of switches and manufacturers.

I now carry a spare and bought the best one I could find. Not cheep.

Practical Sailor tests this type of gear , a subscription might keep you from purchasing the wrong high priced , but low performing switch.

CAVIAT EMPTOR , high price does NOT equal quality.

 

[psneeld]

FF wrote:
I recently had one go out and there are a boat load of switches and manufacturers.

I now carry a spare and bought the best one I could find. Not cheep.

Practical Sailor tests this type of gear , a subscription might keep you from purchasing the wrong high priced , but low performing switch.

CAVIAT EMPTOR , high price does NOT equal quality.

*Any recommendations?* I am in the market for a couple....

 

[rwidman]

RickB wrote:rwidman wrote:*How can you fuse the starting battery?* Any fuse large enough to pass the current required to start the engine would do little or nothing to protect the cables or battery.
P/F's insurance company seems to have unusual powers.

You can fuse a starting battery though. As P/F explained, his worked until it got tired of the abuse and called it quits.

An ANL fuse rated for 500A can withstand more than 1000 for a second or two and that covers the duration of the high inrush current. Once cranking occurs the current drops off dramatically.

The condition for which you might install a fuse at the battery is a dead short between the cable and ground, such as could occur if the cable broke off the solenoid and contacted the block or a screwdrive somehow welded itself in that area. That would open the fuse very quickly and stop the cable from turning the engine room into a toaster oven.

*

I'll admit, I haven't been around a lot of boats, but this is the first time I've heard of fusing the engine starting circuit.

You have to weigh the chance of a short and fire in the starting circuit against the chance of not being able to start the engine because of a blown fuse and drifting into danger.* In this case, he drifted into a dock where someone helped him get started again.* He could have drifted onto the rocks or into another boat.

I have no fuse in the starting circuit and I believe that's the best plan for most of us.

*

 

[Tom.B]

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.


-- Edited by GonzoF1 on Friday 23rd of December 2011 09:08:51 AM