Fused battery connector Up to the task?

[jmschmidt]

I agree with geoffr

[transmitterdan]

Fuses on starter to battery runs are pretty much a waste of $ and not required by ABYC. A fuse from the alternator to the battery might be prudent depending on how the charging wire is routed and the length. Alternators automatically limit output current.

A fuse between battery and starter has to be so large as to be of little use as a safety device.

Fuses from the battery to DC loads or busses are ABYC mandated and should be selected and installed properly. If you don't know the proper type and installation rules get an ABYC trained technician to do it.

[rwidman]

Originally Posted by Cadence

On a house battery Ok. Have the cables as short as possible on the engine battery. No way in hell would I want it fused.

I agree.

The ABYC does not require circuit protection on the engine starting circuit because the fuse would have to have such a high rating that it would be ineffective.

In practice, there could be a time when you need to start your engine right now and you don't have time to search for and install a replacement fuse.

[Cadence]

Originally Posted by rwidman

I agree.

The ABYC does not require circuit protection on the engine starting circuit because the fuse would have to have such a high rating that it would be ineffective.

In practice, there could be a time when you need to start your engine right now and you don't have time to search for and install a replacement fuse.

I had read something about having a spare taped to the cable. BS if you need the engine you need it now not after replacing a fuse in a probably a difficult engine room or space to get to. i'll take my chances on a well dressed cable. Again JMHO

[sharpey]

Thanks for the numerous replies... and variance of opinion.

This certainly gives me something to chew on.... I reckon the bluesea fuses would work on it... so may go that way....

The thing is... the start battery is a good distance away from the engine (Beta 38), so am fitting 2/0 cable to cope with voltage drop. Not sure how that might affect the discussion, since a 150a fuse would blow well before the cable started to sweat (starter draws 100a)...

Again, am relatively inexperienced with all this, but am a quick study...

Again, thanks folks.

James

[sailorboy1]

Originally Posted by Cadence

I had read something about having a spare taped to the cable. BS if you need the engine you need it now not after replacing a fuse in a probably a difficult engine room or space to get to. i'll take my chances on a well dressed cable. Again JMHO

The thing is that a fuse in a circuit should never blow unless there is a problem, in which case replacing the fuse solves nothing. So maybe this should be looked at for a case or having a fire, or having a blown fuse. JMHO

[geoffr]

James

Your setup with 2/0 and 100 amp fuse is pretty much what I'm about to install for our yanmar 3ym30ae, so I see no problems

[CharlieJ]

I have been using these for years and usually buy them a dozen at a time.

I agree with Colin A. in #9; this is a knock off and I would not use it. The Blue Sea MRBFs are manufactured by Bussman and the BUSS is imprinted on each fuse. Here is the link: http://bit.ly/2aplIH8

While the battery terminal that holds the MRBF looks to be perfect ( I could have used it about two months ago!) I have to question if the MRBF/holder has been tested. Fuses and their fuse holders are tested by UL and other certification activities as a system.

OP: Can you provide the supplier's name so more research can be done?

[skipmac]

Originally Posted by transmitterdan

Fuses on starter to battery runs are pretty much a waste of $ and not required by ABYC. A fuse from the alternator to the battery might be prudent depending on how the charging wire is routed and the length. Alternators automatically limit output current.

A fuse between battery and starter has to be so large as to be of little use as a safety device.

Fuses from the battery to DC loads or busses are ABYC mandated and should be selected and installed properly. If you don't know the proper type and installation rules get an ABYC trained technician to do it.

Correct ABYC does not "require" fuses on the starting battery but that exemption was allowed mainly due to the difficulty IE expense of fusing start batteries on really large engines. But if you read the link I posted, members of the ABYC recommend fuses on the starting battery, especially on smaller engines.

The 250 amp fuse on my starter battery terminal would blow before the 00 cable melts so that is certainly acting as a safety device to prevent a fire. Waste of money? Not in my book, especially considering how little it costs.

Fuse between the alternator and battery? Absolutely. It's not the alternator end that's a problem it's the battery end. That wire shorts and you're shorting the full output of the battery and again at risk of melting the wire and starting a fire.

[skipmac]

Originally Posted by rwidman

In practice, there could be a time when you need to start your engine right now and you don't have time to search for and install a replacement fuse.

And I agree with this which is why I wired my system so I turn one switch and the house batteries can be used to start the engine.

However, as someone pointed out, if the fuse in the starter battery blows then you need to solve the problem that caused the fuse blow before trying to start again or you're just shorting the battery and now you're at risk of setting the boat on fire.

[skipmac]

Originally Posted by Cadence

I had read something about having a spare taped to the cable. BS if you need the engine you need it now not after replacing a fuse in a probably a difficult engine room or space to get to. i'll take my chances on a well dressed cable. Again JMHO

But the fuse is NOT going to blow unless there's some kind of problem with the starting system so this is a non issue.

If there is a short that would cause the fuse to blow then you aren't going to be starting the engine anyway.

[skipmac]

Originally Posted by sharpey

Thanks for the numerous replies... and variance of opinion.

This certainly gives me something to chew on.... I reckon the bluesea fuses would work on it... so may go that way....

The thing is... the start battery is a good distance away from the engine (Beta 38), so am fitting 2/0 cable to cope with voltage drop. Not sure how that might affect the discussion, since a 150a fuse would blow well before the cable started to sweat (starter draws 100a)...

Again, am relatively inexperienced with all this, but am a quick study...

Again, thanks folks.

James

This should work just fine. As you note, a 150 amp fuse will blow before a 2/0 cable catches fire so you have protected the system but also have a fuse that will allow sufficient current to run the starter with room to spare. I am assuming your 100 amp draw for the starter to be correct. In case you could go to a 200 amp fuse and still be protected but have a little more cushion for the starter current.

[boatpoker]

Originally Posted by rwidman

I agree.

The ABYC does not require circuit protection on the engine starting circuit because the fuse would have to have such a high rating that it would be ineffective.

In practice, there could be a time when you need to start your engine right now and you don't have time to search for and install a replacement fuse.

It would not be ineffective if sized to the conductor as it should be.

No, ABYC does not require it but, ABYC are "minimum" standards not ultimate.

I'd rather look for a fuse than look for a new cable as they can melt if a solenoid or starter goes.

If you blow a fuse or melt a cable you are not starting that engine until you fix the issue that caused it in the first place.

Do as you see fit but all of my positive conductors are fuse protected.

[skipmac]

Originally Posted by boatpoker

It would not be ineffective if sized to the conductor as it should be.

No, ABYC does not require it but, ABYC are "minimum" standards not ultimate.

I'd rather look for a fuse than look for a new cable as they can melt if a solenoid or starter goes.

If you blow a fuse or melt a cable you are not starting that engine until you fix the issue that caused it in the first place.

Do as you see fit but all of my positive conductors are fuse protected.

Exactly right on all counts.

[sharpey]

Good points again...

Thanks Skipmac.... 200amp fuse makes sense... will order a bluesea one...

CharlieJ, I actually bought this thingamajig out of the UK
Positive Battery Terminal with INBUILT FUSE facility ALT B28712K