Blowing fuses

[luhbo]

The mentioned gold plated bullet connectors are bullet-proof , the right dimension assumed.

 

The R/C folks shoot their electric soarers with 80 amps and more up into the sky. Thats more than you will ever have on your bike.

 

It probably doesn't make sense for every connector or socket, but for those bearing the 30A (max) it would be a real improvement, already proofen by your (and my) melted fuse housings.

 

Hubert

[docc]

I removed the connectors from the fuse block. The wires had been hot on both sides. I can't believe these flimsy things could handle 27 Amps ( obviously they can't). I used the lap splice to add in a separate fuse block for the regulator fuse.

 

 

[kanoa]

hi there, i figured i'd add my fuse-blowing problem

 

i received a new tach from the dealer as a replacement ordered by the PO under warranty (but then the dealership was sold, the bike was sold, and i ended up having to fork over the $$$ for the tach, darn).

 

having the new tach wired up causes the 5A turn-signal fuse (#7) to blow, religiously, but only when the engine is running. i do indeed know the rules, and abide by them. last week i took the tach back off, removed the tank, poked around w/ the multi-meter to find obvious shorts in the turn-signal and tach wiring, found nothing, put everything back together, and the problem persists. and of course, disconnecting the tach fixes the problem

 

i've been working off of carl's amazing wiring diagram and i'm pretty sure i have the tach wired properly, but then again...

 

red/black -> +

black -> ground

yellow/black -> 1

yellow -> bulb

black (circle connector) -> tach mounting screw

 

the fuse simply blows, no melting or excessive heat as above. i can even hear it pop if the seat is off when i fire the bike up.

 

any ideas?

[Guest Gary Cheek]

Thanks, Hubert and Ryan. I'll use some contact cleaner in the connection this morning.

EDIT: Well, I've cleaned them and tightened them up a bit. Hubert's concern about the softness of the metal seems likley. Also , the connections are slightly over 3mm while the fuse blades are 5mm. This hardly seems rated for 27amps. Is going gold enough or should the connectors be 5mm?

 

And to use larger connectors wouldn't the fuse have to be outside the fuse block?

 

 

Those connectors are operating very near at the max rating. Since they are operating near the max and the duty cycle is high they will need to be kept in optimum condition. When a little corrosion creeps in the joint will heat up, as the metal heats it loses tension which adds MORE resistance. The added resistance makes more heat. Once overheated the best repair is replacement. This is an area where CONDUCTIVE grease or past is in order. A little smear on the fuse terminals and a bit applied to the fuse holder contact with a toothpick will seal the joint and increase the effective contact area. There are many applications for the coductive paste on cycles. Just use common sense, a little goes a long ways, remember it is CONDUCTIVE.

 

Metallic Anti Sieze (Aluminum, nickel, graphite paste) compound can be pressed into service as a good sub for the copper bearing conductive paste.

 

BTW It take a few more amps than 30 to actually blow a 30 Amp ATO or ATC automotive fuse.

[docc]

500 miles or so on the new fuse holder and no signs of heat. It was definately the flimsy connectors and the conductivity degradation from the heat cycling.

 

Thanks again for the insight.

[luhbo]

...

red/black -> +

black -> ground

yellow/black -> 1

yellow -> bulb

black (circle connector) -> tach mounting screw

 

the fuse simply blows, no melting or excessive heat as above. i can even hear it pop if the seat is off when i fire the bike up.

 

any ideas?

 

That's how I have mine wired, too.

 

I'd try to disconnect single connectors and look what happens. So disconnect the bulb/yellow first, then cut or remove the black housing ground (without turning loose the post), and so on.

 

What do you mean with "disconnect the tach"? All wires?

 

It could be this is worth its own thread then.

 

Hubert

[Greg Field]

Check the bulb. If it is installed crossways in the receptacle, it will short out and blow the fuse.

[docc]

1000 more very brisk sustained miles in the rain and the fuse looks perfect in its new nest.

 

If your 30 amp regulator fuse is melting it is the connectors in the fuse block.

 

Thanks again to all for their insights.

[docc]

Well, the 30 amp fuse in the external holder burned off its contacts without blowing the fuse. I found this when the battery light came on. Since then I have removed the rubber cap from the fuse holder and relocated it to a less congested location.

 

Still, the fuse runs 150-160 degrees F while the other electrical components (fuses and relays) do not exceed 98.

 

I'm thinking of going to a full size fuse as is used in the power distribution consoles of automobiles.

[OldButNotDead]

Well, the 30 amp fuse in the external holder burned off its contacts without blowing the fuse. I found this when the battery light came on. Since then I have removed the rubber cap from the fuse holder and relocated it to a less congested location.

 

Still, the fuse runs 150-160 degrees F while the other electrical components (fuses and relays) do not exceed 98.

 

I'm thinking of going to a full size fuse as is used in the power distribution consoles of automobiles.

 

How odd. Seems like a fuse that melts it's plastic but not the fusible metal isn't designed properly?

 

I've managed to avoid thinking about this issue until now, as I haven't had major electrical issues with the bike.. Your woes prompted me to take a close look at my 30 amp fuse.

 

Yup - slightly deformed plastic on one end! I'll likely go the dlaing route with a dedicated fused hotwire at some point...

[docc]

How odd. Seems like a fuse that melts it's plastic but not the fusible metal isn't designed properly?

 

I've managed to avoid thinking about this issue until now, as I haven't had major electrical issues with the bike.. Your woes prompted me to take a close look at my 30 amp fuse.

 

Yup - slightly deformed plastic on one end! I'll likely go the dlaing route with a dedicated fused hotwire at some point...

 

That's what I did: a hard wired fuse holder outside the fuse block. Yet, it's still obviously very hot.

 

Not sure what to do next . . .

[Greg Field]

Docc:

 

WHile it's hot, run a finger along the run of wire to find out where it's hot, and where it's not. THat'll help you determine if there's a localized resistance and where it is.

[OldButNotDead]

That's what I did: a hard wired fuse holder outside the fuse block. Yet, it's still obviously very hot.

 

Not sure what to do next . . .

 

Doing a couple of minutes of googling now leads me to believe that it's not too unusual for fuse holders / wires / solder to melt before a 30 A fuse blows. So, I'm thinking that aspect's not unique or particularly important.

 

Drawing from my vague recollections of discussions past, my best guess is that there's a bad ground associated with the charging system (intermittent?) and it occasionally pushes out too much current. Not a new idea, just the one I'm voting for.

 

As for toubleshooting...I'm not ready to dig into mine, but when I do I will sketch out a plan using this: http://www.tracyamartin.com/WebPages/MotorBook.html. My first time through I found it pretty clear, if not concise.

 

Voltage drop testing while a system is running seems to be the most effective approach. Course, if it is intermittent, then identifying, cleaning and reconnecting everything associated with the charging system might be the only "surefire" way. My apologies (and condolences) if you've already tried all this....

[badmotogoozer]

This is a resistance problem and it will be right where the heat is. Likely some resistance has built up over time at the point that the fuse blades contact the holder.

 

Let's put some numbers together as there seem to be many folks here who need numbers...

 

It isn't a current problem, otherwise the fuse would blow. Let's say that it wouldn't be unusual for a circuit with a 30A fuse to be drawing 25 amps under normal operation. Ideally the fuse connection would be resistance free but in the real world this is usually around 100 milliohms or less.

 

Let's next assume that over time oxidation, high current arcing, and/or vibration have caused this resistance to increase, let's say it is now 2 ohms (not uncommon).

 

Power dissipated = I^2 X R, or 25^2 X 2 = 1250 watts. This is how much power will be consumed by this deteriorating condition, and it will be dissipated in the form of heat.

 

Compared to the original state 25^2 X .100 = 62.5 watts.

 

You can see that in a high current scenario, even a slight increase in resistance creates a massive increase in heat.

 

Find where the heat is and you will find the poor connection. Resistance can be lowered by cleaning with contact cleaner and cycling the fuse in an out a few times, increasing tension on the fuse holder sockets with a small screwdriver, or replacing the fuseholder altogether with a heavy duty unit rated for high current.

 

cheers,

[luhbo]

Nice figures, Ryan.

 

62 Watts - anybody out there willing to touch a 62 Watt bulb? Probably not.

 

The only solution for those who need one would be an electronic fuse. Such a device works nearly lossless, alas it's all but cheap.

 

Hubert