Positive Rectifier To Battery Wire, Fused Or Not?

[retiredgentleman]

The Yamaha engineers knew where to put a fuse, and how to wire a motorcycle.
Whenever you have a large power source, such as a battery, the positive terminal must be fused as close to the positive terminal as possible. The fuse must come first before any other wiring or components. Only the wiring and components down stream of the fuse will be protected. Any wiring that comes directly from the battery, will heat up and melt. The copper wiring of #18 or #16 or even #14 gauge will melt very quickly if there is a short circuit.

I've worked in various industrial settings, which had very large battery banks capable of 1000s of amps of current. The first thing you find leaving the positive terminal is a fuse. To not have a fuse as the first item in the circuit, means the whole building could burn down
if a short circuit occurs.

 

[mrtwowheel]

The Yamaha engineers knew where to put a fuse, and how to wire a motorcycle.
Whenever you have a large power source, such as a battery, the positive terminal must be fused as close to the positive terminal as possible. The fuse must come first before any other wiring or components. Only the wiring and components down stream of the fuse will be protected. Any wiring that comes directly from the battery, will heat up and melt. The copper wiring of #18 or #16 or even #14 gauge will melt very quickly if there is a short circuit.

I've worked in various industrial settings, which had very large battery banks capable of 1000s of amps of current. The first thing you find leaving the positive terminal is a fuse. To not have a fuse as the first item in the circuit, means the whole building could burn down
if a short circuit occurs.

Ok, I can agree about the placement of a fuse in relation to a battery. I think the same should go for that positive wire on the rectifier, it's on the wrong side of the fuse to protect anything.

 

[5twins]

Power isn't feeding into that red wire on the rectifier, into the rectifier. That's the converted DC power flow out of the rectifier to the battery to charge it.

 

[retiredgentleman]

That fuse is only there to stop the high current from the battery, from melting down stream wiring and causing a fire. That fuse has nothing to do with the power coming from the alternator via the rectifier. If a short circuit to ground occurs on the rectifier output wire or at the ignition switch,the engine will stop because there is no voltage for the ignition system, and the 20 amp fuse would blow as well.

There are 2 possibilities for the short circuit, if a ground occurs, for example at the ignition switch/rectifier output.

1) There are 2 sources of current. The engine is running and approximately 8 to 10 amps is flowing from the rectifier output wire to the ignition switch. The engine will stop because the ignition voltage drops to zero. The 20 amp fuse will blow to stop 100s of amps from flowing from the battery. The 2 sources are removed.

2) There is only 1 source of current. The engine is not running, so we don't have the 8 to 10 amps from the alternator.
The 20 amp fuse blows to stop 100s of amps. The 1 source is removed.

 

[mrtwowheel]

I'm finding a whole lot of diagrams with the wiring done the way that RG says is the wrong way.

Scott

 

[retiredgentleman]

I'm finding a whole lot of diagrams with the wiring done the way that RG says is the wrong way.

Scott

This is the wild internet, where many people change wiring diagrams. If people have no electrical knowledge, they may make changes to diagrams that are unsafe, even dangerous. A wiring diagram is only correct if the last person who edited it , knew what they were doing. Care to post an example of what you have found?

 

[mrtwowheel]

Asshole, I know when I'm being called a liar. Check yourself.

 

[mrtwowheel]

So, I see that Honda wired their rectifier wire before the main fuse on their early GoldWings. That's the way that my 650 will be wired. I don't think that Honda would have compromised a bike that took that much R&D.

 

[xjwmx]

the fuse will blow anyways, whichever side of the fuse gets hot.

It doesn't work like that. Current has to go through a fuse to make it blow. In other words, where it says "A.C.Generator" in Gary's diagram, if that point was connected to ground the fuse would blow. But if that wire was connected to the other side of the fuse the path wouldn't be through the fuse so it wouldn't blow. The current through the fuse has to be more amps than the fuse rating and then it will blow.

 

[mrtwowheel]

No, wire gets hot, fuse gets hot, wire is connected to fuse, fuse burns when it gets hot.

 

[xjwmx]

No, wire gets hot, fuse gets hot, wire is connected to fuse, fuse burns when it gets hot.

Very interesting fundamental misunderstanding. A 10A fuse is designed to blow when it gets more than 10A through it. 10A on just one side of it isn't something that even makes sense. Imagine a very thin wire between two terminals of a battery -- it burns in two -- that's a fuse.

 

[retiredgentleman]

It doesn't work like that. Current has to go through a fuse to make it blow. In other words, where it says "A.C.Generator" in Gary's diagram, if that point was connected to ground the fuse would blow. But if that wire was connected to the other side of the fuse the path wouldn't be through the fuse so it wouldn't blow. The current through the fuse has to be more amps than the fuse rating and then it will blow.

Exactly correct.

 

[retiredgentleman]

So, I see that Honda wired their rectifier wire before the main fuse on their early GoldWings. That's the way that my 650 will be wired. I don't think that Honda would have compromised a bike that took that much R&D.

Will you post this wiring diagram, or post the link to it so I can see if this is as stated?

 

[retiredgentleman]

Very interesting fundamental misunderstanding. A 10A fuse is designed to blow when it gets more than 10A through it. 10A on just one side of it isn't something that even makes sense. Imagine a very thin wire between two terminals of a battery -- it burns in two -- that's a fuse.

Yes, mrtwowheel has very weak electrical knowledge.

 

[xjwmx]

Yes, mrtwowheel has very weak electrical knowledge.

It's a specialty...

 

[mrtwowheel]

So, you guys are all in agreement that a short that causes heat to that red wire will only blow the fuse if it is connected on a certain side of the fuse? Who the hell is full of shit here?

 

[Bob Kelly III]

Asshole, I know when I'm being called a liar. Check yourself.

Mrtwowheels: before you get mad and call someone an asshole again consider that these guys are trying to HELP you.... it's not a competition of cleverness and which is a better way, if you want a better way attach a fuze to every hot wire in the bike on every component !
Yamaha did it as cheap as possible but still having adequate protection.
it would be detrimental to have the bike burn up just because the Rec/reg went bad , better to Kill the whole electrical system than that !
Right ? if you cannot see that by looking at the diagrams then perhaps your understanding of how the electricity works is wrong it's not THEM it's YOU.... don't get your panties in a bunch THINK outside the box and perhaps you'll learn something eh ?
.....
Bob.......

 

[Bob Kelly III]

So, you guys are all in agreement that a short that causes heat to that red wire will only blow the fuse if it is connected on a certain side of the fuse? Who the hell is full of shit here?

Correct ! if that wire is before the fuze the fuze has no amperage going through it and the fuze is useless in this case the red wire has to be after the fuse to have any chance of the fuse blowing to save the system.
and it's not a case of being full of shit, try it yourself, take a fused wire and touch it between the terminals of a battery.... it blows the fuse now
take another wire and attach the wire to one end of the fuze now touch the new wire to the battery terminal.... the fuze will not blow if there is no current going through it ! calm down and learn, class is in session and you can learn allot here ! be nice !
.....
Bob........

 

[xjwmx]

Correct ! if that wire is before the fuze the fuze has no amperage going through it and the fuze is useless in this case the red wire has to be after the fuse to have any chance of the fuse blowing to save the system.
and it's not a case of being full of shit, try it yourself, take a fused wire and touch it between the terminals of a battery.... it blows the fuse now
take another wire and attach the wire to one end of the fuze now touch the new wire to the battery terminal.... the fuze will not blow if there is no current going through it ! calm down and learn, class is in session and you can learn allot here ! be nice !
.....
Bob........

LOL. I'm riding out to CA soon, and I might have to find out where Weed is and look you up.

 

[mrtwowheel]

Bob, if you haven't noticed, I don't need help. Read the whole thread Bob.