Battery main fuse

You'd be a few cards short of a deck if you didn't realise it was causes of fires!! (Battery main fuse thread?)

Not sure where I got it from but why don't you do a google (image) search on something like " cause of boat fires fuel engine electrical":rolleyes:
 
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GHA said:
from here looks like >
https://www.boatus.com/seaworthy/magazine/2015/october/boat-fires.asp
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""Stoves. The incidence of fires due to stoves has decreased with the gradual replacement of alcohol stoves with propane stoves and electric ranges. Two percent of fires were caused by stoves, more than half resulting from problems with lighting alcohol stoves. Given how few alcohol stoves there are on boats these days, they are significantly more dangerous than those that use other fuel sources.""
 
It's interesting that only 32% of all boat fires are caused by DC electrics but still does not tell me how many were caused by main cable failure. My guess is that most were caused by sub standard wiring. Just to be clear I am not advocating not fitting fuses, I am just trying to analyse risk...... I am also suspicious of a pie chart that does not mention gas installations as a major cause. I am personally aware of at least 3 boat fires caused by poor LPG installations.
 
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boatmike said:
It's interesting that only 32% of all boat fires are caused by DC electrics but still does not tell me how many were caused by main cable failure. My guess is that most were caused by sub standard wiring. Just to be clear I am not advocating not fitting fuses, I am just trying to analyse risk...... I am also suspicious of a pie chart that does not mention gas installations as a major cause. I am personally aware of at least 3 boat fires caused by poor LPG installations.
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Firstly, it's an American report from about 5 years ago, based on one company's insurance claims. Of the DC electrical fires, over half were engine or battery related.

The pie chart has an "Other" category, which includes stove fires. The report says "Two percent of fires were caused by stoves, more than half resulting from problems with lighting alcohol stoves."

As for fuses, the amount of energy stored in a battery bank is frightening. Why wouldn't anyone fit a fuse to be on the same side?
 
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William_H said:
A couple of months back a boat in our yacht club marina had a pretty scary electrical fire. There was no fuse fitted and I believe it was the wire alternator to battery which chafed through the insulation due to poor attachment. So yes a fuse would have saved the problem bu then so would decent mounting of the wiring. ol'will
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I had something similar happen last year, except it was the insulation on the battery to starter-motor cable that chafed through against the the speed-control quadrant on the engine. (Because it is a pre-engaged starter that cable is energised whenever the electrics are turned on, and the cable routing had been disturbed slightly when the exhaust elbow was changed at the start of the season.) This caused a major short-circuit, melting/vaporising the insulation on the starter cable between the point of the short-circuit and the 1-2-Both switch and also the insulation on the negative battery lead. Part of the negative battery post melted, and the circuit was only broken when the spindle of the 1-2-Both switch got so hot it melted its plastic support and the rotating part of the switch came away from the fixed contacts (which is why I could not turn it when I tried to isolate the battery). I don’t know if this is a design feature or just an accident, but it does seem as if the switch acted as a high-current fuse, and without it I might well have had a fire on my hands. I have now installed a battery main fuse in the common negative line.
 
The trouble with fuses in what essentailly boils down to the starter circuit, is that they don't always offer great protection.
If you size your fuse to allow for worst-case needs of the starter motor, you can find that the fuse may not always blow under fault conditions. If you size the fuse to be sure of it blowing, it might blow when you really, really don't want it to.

The worst case is perhaps starting the engine when the starter battery is reaching the end of its life.
In that situation, I want the engine to have every chance of starting.
I might be depending on it to get out of the way of a ship or something.

Very few cars have fuses in the start circuit. Very few cars catch fire.
 
lw395 said:
Would you care to take us through how you chose the fuse?
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Let's hope he has more of a clue than you, you can't work out how to select a fuse that can carry the max starter current, but still blow in the case of a short circuit. Hardly rocket science, is it ?
 
PaulRainbow said:
Let's hope he has more of a clue than you, you can't work out how to select a fuse that can carry the max starter current, but still blow in the case of a short circuit. Hardly rocket science, is it ?
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Actually it's quite hard to find a fuse that does the job properly, rather than just offering a false sense of security and/or an unnecessary failure point.
Could be why car makers don't go there.
 
lw395 said:
Actually it's quite hard to find a fuse that does the job properly, rather than just offering a false sense of security and/or an unnecessary failure point.
Could be why car makers don't go there.
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More ill informed nonsense. Starter fuses, alternator fuses etc all common place on many modern cars. You're possibly thinking of the Cortina you used to own, but things have moved on :encouragement:
 
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