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MRBF without fuse holder

Dadoftheturkeykids

Dadoftheturkeykids

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Is there a reason to use the little fuse holders? If I were to just mount the little cube fuse directly onto the post with cable lug on top, would that provide the same protection?

Wouldn't it provide less loss/resistance as well? Being that there would be less connections and less random metal spacing?
 
I just thought a little more in depth on the fuse holders and realized that the post looks like it is separated from the busbar by a very small bit of plastic.. Maybe that is the reasoning for the holder?
 
In my experience they were around for years (like a decade or more??) before there was a bolt on holder for them. Ironically it defeats the purpose of them being for "space constrained" applications.
 
Lol frustrating to think about. I guess even if the stud is separated from the base, the fuse contacts both the lug on top and the busbar(on the fuseholder)
 
I think without this fuseholder, the bolt is in parallel with fuse element, defeating it.

1712791842068.png

It seems like a bolt plus top-hat insulating washer could work.
 
They react in about the same time as a class T does. I.e. to a short they blow very quick. To just double current they can take a while.

They can't be used without some kind of holder except with insulated stud. The problem with anything but the holder is getting the proper torque for a good connection.
 
Last edited:
robbob2112 said:
The problem with anything but the holder is getting the proper torque for qa good connection.
Click to expand...
This makes sense being that battery studs tend to be pretty short, but couldn't you just buy longer studs? I recall another member arguing that the mrbf should be on the busbar not the battery terminal but I kind of don't see the logic there as the wire wouldn't be protected.
 
I had the same fart a couple weeks ago, the 3/8 hole is perfect for Bluesea disconnect (for those who live the 24v life) for a relatively clean install in DIY battery box builds.
 
timselectric said:
Crap, your right.
I had a brain fart. lol
Click to expand...
:fp2:ROFLMAO:Full disclosure.... Years ago, like early 2000's. Outback supplied them in the kit with thier inverters with ZERO instructions or a holder. I just popped them on the battery positive and went on with my day. Guess that explains why I never got any call backs on them. Ignorance is bliss!!
 
Dadoftheturkeykids said:
This makes sense being that battery studs tend to be pretty short, but couldn't you just buy longer studs? I recall another member arguing that the mrbf should be on the busbar not the battery terminal but I kind of don't see the logic there as the wire wouldn't be protected.
Click to expand...

If you are doing more than 2 parallel batteries the fuse should be at the bus bar. If doing a single or pair of batteries the fuse can be on either end with no problem. This is how the math works out.
 
Dadoftheturkeykids said:
Doesn't the stud become one with the fuse once you torque on the wire lug?
Click to expand...


For the fuse to work one side must be touching the hot of the battery and the other must be one with the stud. That way the current flows through the fuse verse around it. Not to mention a stainless steel stud isn't a very good conductor so it would heat if you forced current through it like that.

Look close at the fuse. The top ring and bottom ring are separated by a ceramic and there is a filament visible through the plastic on one side only. That is the intended current path.
 
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