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Old 12-20-2011, 06:00 AM   #21
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RE: Battery Switch Location and Emergencies

Quote:
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. .......
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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.
*
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Old 12-20-2011, 07:55 AM   #22
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RE: Battery Switch Location and Emergencies

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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.
*
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Old 12-20-2011, 09:16 AM   #23
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RE: Battery Switch Location and Emergencies

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.**

*

*

*

*
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Old 12-20-2011, 02:02 PM   #24
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RE: Battery Switch Location and Emergencies

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.

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Old 12-22-2011, 07:47 AM   #25
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RE: Battery Switch Location and Emergencies

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skipperdude wrote:I like things simple.
*I like your approach. Simple, reliable as long as the switches are good quality, and virtually bulletproof.
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Old 12-22-2011, 08:37 AM   #26
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RE: Battery Switch Location and Emergencies

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.

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Old 12-23-2011, 04:15 AM   #27
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RE: Battery Switch Location and Emergencies

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.
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Old 12-23-2011, 05:07 AM   #28
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RE: Battery Switch Location and Emergencies

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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....
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Old 12-23-2011, 07:41 AM   #29
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RE: Battery Switch Location and Emergencies

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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.

*
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Old 12-23-2011, 08:07 AM   #30
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Battery Switch Location and Emergencies

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
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Old 12-23-2011, 08:28 AM   #31
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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
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Old 12-23-2011, 08:58 AM   #32
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Battery Switch Location and Emergencies

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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.
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
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Old 12-23-2011, 10:19 AM   #33
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RE: Battery Switch Location and Emergencies

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!
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Old 12-23-2011, 10:25 AM   #34
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RE: Battery Switch Location and Emergencies

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.
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Old 12-23-2011, 10:29 AM   #35
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RE: Battery Switch Location and Emergencies

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................. 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.
*
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Old 12-23-2011, 10:44 AM   #36
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RE: Battery Switch Location and Emergencies

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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?
*In a word, yes.
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Old 12-23-2011, 02:40 PM   #37
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Battery Switch Location and Emergencies

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
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Old 12-23-2011, 04:40 PM   #38
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RE: Battery Switch Location and Emergencies

Ooops.... My bad. I read my schematic wrong. SORRY!!! Please resume.
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Old 12-24-2011, 04:14 AM   #39
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RE: Battery Switch Location and Emergencies

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.
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Old 12-27-2011, 11:26 AM   #40
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RE: Battery Switch Location and Emergencies

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!
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