Fuses on each battery

[catmandoo]

Sterling recommends fuses on the positive side of each battery bank . While the reason is understood I don't thing it is practical in most boats although I can't comment on steel canal boats . It involves 100 amp or above fuses and bulky fuse holders in the restricted space around the battery boxes with out any adjacent suitable bulk head space to mount them .

Risk of shorting out the battery in a glass fibre boat is minimal if the battery locker is secure from stray metal and if the negative cable is easily disconnected when doing maintenance .


I wonder how many boats actually fit them .. Any comments ?

In my case I am removing split charge diodes and replacing with a Sterling Pro split R and the only risk was around the alternator feeds but the diodes prevented this from happening

 

[prv]

I have fuses on my batteries, because I don't have separate master switches. Can't remember the exact values; I think the engine battery may be 500amps and the house perhaps 200 (not that I ever expect to draw that much). They are Megafuses (like this) and each sit in a little plastic holder attached to the positive terminal and sitting on top of the battery. You'd need to be seriously short of space for this not to fit.

Pete

 

[pmyatt]

Sterling recommends fuses on the positive side of each battery bank . While the reason is understood I don't thing it is practical in most boats although I can't comment on steel canal boats . It involves 100 amp or above fuses and bulky fuse holders in the restricted space around the battery boxes with out any adjacent suitable bulk head space to mount them .

Risk of shorting out the battery in a glass fibre boat is minimal if the battery locker is secure from stray metal and if the negative cable is easily disconnected when doing maintenance .


I wonder how many boats actually fit them .. Any comments ?

In my case I am removing split charge diodes and replacing with a Sterling Pro split R and the only risk was around the alternator feeds but the diodes prevented this from happening

It is a mandatory requirement on all American built boats. The fuse should be as close to the battery as physically possible and should be rated just above the maximum expected output draw of the battery. It is designed to protect the cable beyond the battery from a battery "Run Away" - if you have a battery cable run under saloon floor, or similar, do you really want it to catch fire at that point, or at some even more inaccessible point in the cable run? We have 650 Ah domestic bank, regularly draw 120 Amps and charge at up to 150 Amps - fuse on Positive cable is 200 Amps. Have, in fact, only just moved the fuse to put it right next to batteries; it was the other side of the saloon by the power panel.

 

[catmandoo]

I have fuses on my batteries, because I don't have separate master switches. Can't remember the exact values; I think the engine battery may be 500amps and the house perhaps 200 (not that I ever expect to draw that much). They are Megafuses (like this) and each sit in a little plastic holder attached to the positive terminal and sitting on top of the battery. You'd need to be seriously short of space for this not to fit.

Pete

I had a look at the Sterling ones and the fuse holders looked ginormous and designed to be mounted on a board . Also coat £100 for 4 batteries complete kit . I have been looking for ones you could attach directly to battery terminal such as you suggest but could not find a supplier with a picture of the holder I suppose it doesn't matter which terminal positive or negative same current passing through!

The other issue is that fuse must be accessible or that I have a strategy for making a quick fix in an emergency

 

[basil421]

These people do quite reasonably priced fuses and holders
http://polevolt.co.uk/acatalog/info_MEGA1.html
I used them for some parts recently and had good service.

 

[prv]

I have been looking for ones you could attach directly to battery terminal such as you suggest but could not find a supplier with a picture of the holder

These are the ones I have: http://thewiringproject.co.uk/showdetails.asp?id=851

At one end, I have a "cable" which is so short as to be a solid link - there's a gap of about a millimetre between the crimp-on lugs. The lugs are then bolted one to the terminal that fits around the battery post and one to the terminal in the fuse holder. The cable away to the starter motor or supply busbar (depending on battery) is bolted to the terminal at the other end of the fuse holder. I have an insulated spanner which fits all these various nuts (same size) and I take the fuses out before doing any work on the engine electrics or the house supply upstream of the switch panel.

Pete

 

[CelebrityScandel]

It is a mandatory requirement on all American built boats. The fuse should be as close to the battery as physically possible and should be rated just above the maximum expected output draw of the battery...

I guess you don't live on this side of the Atlantic else you would know that in fact ABYC allows distances of up to 72 inches from house batteries to the protection (distance depending on extent of sheathing and protection of the cable). That in many instances gets you to the breakers on the main panel in which case the battery cables need not have fusing at all.

Furthermore, ABYC specifically exempts battery cables to the engine starting motor from fusing.

 

[catmandoo]

I guess you don't live on this side of the Atlantic else you would know that in fact ABYC allows distances of up to 72 inches from house batteries to the protection (distance depending on extent of sheathing and protection of the cable). That in many instances gets you to the breakers on the main panel in which case the battery cables need not have fusing at all.

Furthermore, ABYC specifically exempts battery cables to the engine starting motor from fusing.

Yes I have a 3 pole manual isolator switch (in an outside locker) to all various boat users about 1.00m from the batteries ( I have 3 banks ) The two supplies to the starter switch from starter battery and no 2 battery by pass this but go directly to the separate battery selector switch but close by . Under the above rules then it would appear that I don't need any fuses at all And my only problem would be during maintenance . However I disconnect the negative completely at the battery posts when working around the batteries .

I should perhaps invest in terminal covers on the positive poles however

 

[catmandoo]

Yes I have a 3 pole manual isolator switch (in an outside locker) to all various boat users about 1.00m from the batteries ( I have 3 banks ) The two supplies to the starter switch from starter battery and no 2 battery by pass this but go directly to the separate battery selector switch but close by . Under the above rules then it would appear that I don't need any fuses at all And my only problem would be during maintenance . However I disconnect the negative completely at the battery posts when working around the batteries .

I should perhaps invest in terminal covers on the positive poles however

Oh Oh Breakers on main panel though - presume manual isolator not enough then ??????

So as afterthought all I need is auto CBs on main panel or in line fuses at main panel to protect supply lines from battery isolator switch

 

[nigelmercier]

Depends if you like fire on not.

 

[pmyatt]

I guess you don't live on this side of the Atlantic else you would know that in fact ABYC allows distances of up to 72 inches from house batteries to the protection (distance depending on extent of sheathing and protection of the cable). That in many instances gets you to the breakers on the main panel in which case the battery cables need not have fusing at all.

Furthermore, ABYC specifically exempts battery cables to the engine starting motor from fusing.

My source says 7" from battery, not 72" for domestic bank; agreed that rules are less strict for starter battery but there is no exemption.

 

[davidwf]

I have terminal fuse blocks fitted to my Beneteau, very compact

Blue seas do one see http://bluesea.com/productline/overview/378

 

[pmyatt]

I have terminal fuse blocks fitted to my Beneteau, very compact

Blue seas do one see http://bluesea.com/productline/overview/378

Absolutely ideal if you have the room to fit them - but, if memory serves me correctly, they are 2" tall. It is sometimes easier to fit an in-line fuse on a short length of leader cable.

 

[catmandoo]

risk

Depends if you like fire on not.

Well boats 30 years old and still surviving and not much change to system logic so I guess a couple of years more will see me out ..with a bit of common sense

By the way I have done a lot of Hazops in my time on Process systems much more flammable than a plastic boat

 

[CelebrityScandel]

My source says 7" from battery, not 72" for domestic bank; agreed that rules are less strict for starter battery but there is no exemption.

You are persistant aren't you? Instead of your referring to some anonymous "source" of which we have no knowledge whatsoever of its credibility you need to quote from ABYC E11 "AC and DC Systems on Boats", in particular Figure 15.

If you do that you will see that everything I said is correct.

EDIT: I should really add as well that while ABYC publishes what are effectively the "national" standards for vessels under 150 foot compliance with them is not mandatory. There is no legislation in the US that makes compliance with these standards or, as you claim, the fusing of battery cables a requirement for pleasure vessels. If you believe otherwise please refer us to the relevant CFR or other enabling legislation.

 

[Bosun Higgs]

Risk of shorting out the battery in a glass fibre boat is minimal if the battery locker is secure from stray metal and if the negative cable is easily disconnected when doing maintenance .
I wonder how many boats actually fit them .. Any comments ?

I would have said the same until I saw ( and subsequently repaired) a boat where there had been a dead short on the battery cables and a fire as a result. What happened was that one of the engine mounts gave way in a bad sea and the flange between the block and the sump chafed through the positive wire to the starter. In the resulting dead short the battery cables overheated, melted their insulation, melted through the tops of the batteries ( acid all over) and set fire to the woodwork of the galley. They had one stroke of luck - the rotary battery switch still worked to my amazement.

So yes its a very small chance of a problem but when it happens its a survival situation.

 

[AlanCA]

You are persistant aren't you? Instead of your referring to some anonymous "source" of which we have no knowledge whatsoever of its credibility you need to quote from ABYC E11 "AC and DC Systems on Boats", in particular Figure 15.

If you do that you will see that everything I said is correct.

EDIT: I should really add as well that while ABYC publishes what are effectively the "national" standards for vessels under 150 foot compliance with them is not mandatory. There is no legislation in the US that makes compliance with these standards or, as you claim, the fusing of battery cables a requirement for pleasure vessels. If you believe otherwise please refer us to the relevant CFR or other enabling legislation.

I'm arrive to this debate rather late, but for anyone else who comes along later - ABYC says 7" for plain insulated wire, 72" if the insulated wire is then placed in an enclosure or sheath AND is connected directly to the battery at one end, and 40" if it is in the enclosure but it is NOT connected directly to the battery. There seems to be no mention (or I have not found it) as to how soon it needs to get into the sheathing (ie: within 7"?). In practicality, I do not see boats with enclosed battery cables, and you also need to consider the increased wire size if doing so, as the ampacity specs change when bundled and/or sheathed. The poster is correct that ABYC is not law, and not required on uninspected boats. But if you want insurance, (which you do!), the surveyor will likely require that you meet main recommendations of ABYC. That said, you'll likely get away with 12" instead of 7" - that shorter length is given a bit of leeway if the fuse is mounted on the closest surface, for instance.