No electrical fuse?

[wanabeguru]

Originally Posted by stealthcrf

You can fuse the black ground wire coming from the magneto (toward CDI unit) to isolate the entire bike, but it is not really needed. Make sure that you don't remove the inline diode (illustrated by the triangle over rectangle in the diagram)

Are you sure that is a diode or is it a symbol to indicate an in-line connector possibly of the bullet type???

[stealthcrf]

DOH! Sorry, I'm stuck diagnosing auto electrical all day long. Don't... Rarely ever see that one. Assumption is the mother of...

Yes, standard method is to fuse the B+ (or non-B + lol) but on a simple system a load protection on the ground side would work as well. And since this is before the chassis ground (the reason for fusing positive circuits) fusing the ground between magneto and CDI would be a cleaner method. I tend to deviate from standard when I can make a circuit simple, so long as it is thought out properly.

For the clarification of others: In complex or mulitple circuit systems, that have negative earth (chassis grounded to -) then fuses are installed on the positive side as they are many. One giant fuse on the negative would lead to small shorts causing damage, and large current shorts would blow the fuse for everything. As this would be a simple one fuse for all, the ground path could be fused as simply as the positive side, although that is very unorthodox. Sorry, I should have explained more clearly to start.

[wanabeguru]

Originally Posted by stealthcrf

DOH! Sorry, I'm stuck diagnosing auto electrical all day long. Don't... Rarely ever see that one. Assumption is the mother of...

Yes, standard method is to fuse the B+ (or non-B + lol) but on a simple system a load protection on the ground side would work as well.

it would work but wouldn't protect anything on the wiring all the way back to the source as it would remain "hot"! That is why the high side[non ground reference] is fused.
Now lets put this one to bed. I think the OP's intent was to use a higher output lighting portion of the magneto which may be useless as that usually refers to POWER CAPABILITY. Then fuses came along and was one needed. Simply, yes. All loads should be properly fused to protect the circuits/wiring. Good night all.

[stealthcrf]

There is no battery. The magneto is the source, and they would be hot with nothing to short to if the fuse blew. Popping a fuse on the ground path would be like disconnecting the negative cable on an automobile. The hot wires are still B+, but there is no path for them to ground.

Anything susceptible to damage would be so no matter where the fuse was, until the fuse blew, and then it would be safe, no matter where.

[wanabeguru]

Yes, as long as you can guarantee the fuse is exceptionally close to the low side of the supply.
As a side note-there must be a reason everyone fuses the high side of their power systems, don't you think?

[stealthcrf]

Yep, many + circuit paths going to a single -, in those cases, it is much more feasible to fuse the positive, and since the ground is not fused, any shorts to ground must be fused on the positive side. In this case there are really two circuits, neither of which is very complex, so the poster can fuse the one circuit as he mentioned, or he could run two fuses, or fuse the entire thing on the ground side. Since it is such a simple setup that will likely never blow a fuse, I made the suggestion. It provides more protection than stock, but without the separation that most are familiar with.

I've worked on vehicles that have a big warning label "THIS VEHICLE IS POSTIVE EARTH!" It makes your head hurt for a while after reading the diagrams.

[wanabeguru]

Absolutely!! I'm with you. Sometime try going from electron flow to hole flow halfway through a schematic---basically a reversal of the reference points.

[stealthcrf]

HAHAHA, the one time I mentioned electron flow, the only guy in management that knew what I was talking about threw down his paperwork and sneered "so you're one of THOSE guys!" as if I had stated the world was flat.

[wanabeguru]

Boy, am I glad this one is done! Can I go to bed now? lololol

[focus frenzy]

I would like to point out that this electrical system is designed just to power the two little bulbs, no battery charging, no turn signals so all it has to do is provide just enough power for those two bulbs. there is no regulator, it doesnt produce enough current to require one, it only makes 40 watts.

so a fuse is a mute point because it wont produce enough current to blow a fuse large enough to handle the lighting load.

[wanabeguru]

Originally Posted by focus frenzy

I would like to point out that this electrical system is designed just to power the two little bulbs, no battery charging, no turn signals so all it has to do is provide just enough power for those two bulbs. there is no regulator, it doesnt produce enough current to require one, it only makes 40 watts.

so a fuse is a mute point because it wont produce enough current to blow a fuse large enough to handle the lighting load.

You may want to read post #'s 5&13

[focus frenzy]

Originally Posted by wanabeguru

You may want to read post #'s 5&13

I did read them, what good is a 5 amp fuse on a electrical system that makes 3-1/3 amps max?? short to ground is not going to blow the 5 amp fuse if the lighting coil won't produce 5 amps.

wires to the lights is large enough to handle the whole load.

[wanabeguru]

Originally Posted by focus frenzy

I did read them, what good is a 5 amp fuse on a electrical system that makes 3-1/3 amps max?? short to ground is not going to blow the 5 amp fuse if the lighting coil won't produce 5 amps.

wires to the lights is large enough to handle the whole load.

Same reason main breaker on a 200Amp service is 50,000Amp INSTANTANEOUS rating. But go ahead and think that lighting coil won't/isn't capable of producing 5 Amps. I'll offer you a one time special of 2 for 1 on my patented smoke re-injection kits; just pay S&H on second kit! Happy wiring!!