To the electrically minded

Case 1 : no bad connection
R1 = 0 ohm
V1 = V2 = 12v
Current = 12v/1ohm = 12 amps
Power in R1 = 0v * 12a = 0 watts
Power in R2 = 12v * 12a = 144watts
Total power delivered by source = 144 watts
Total current delivered by source = 12a

Case 2 : bad connection
R1 = 1 ohm
V1 = 12v
V2 = 6v
Current = 12v / (1ohm + 1 ohm) = 6 amps
Power in R1 = (12v - 6v) * 6a = 36 watts
Power in R2 = 6v * 6a = 36 watts
Total power delivered by source = 36w + 36w = 72 watts
Total current delivered by source = 6a

Notice that even though the bad connection is using way more power in case 2 than in case 1, the total current and total power are way down in case 2. Also, notice the load gets 1/4 the power in case 2 than it did in case 1. That's why a bad connection can affect the performance so much.

Post edited by: loudhvx, at: 2007/06/14 14:04

So that bad connection is continuous dropping the effective power of the system, potiential to below break even?

I just want to make sure i know what I'm looking for. Would a partial arch to ground fit the symptoms better?

Well, my point is that a bad fuse connection, in your situation, should have cause the battery to get more current and thus higher voltage. In other words it should have helped the battery, (but would make the bike run poorly and the lights dim).

Now a short to ground would make sense. If the intermittent short to ground was after the fuse, it would make the fuse heat up, the bike run poorly, and reduce the current to the battery. This describes your problem more accurately. However, this means the fuse would be close to blowing from over-current, and it should show up on the clamp meter as high current if you measure the amps on the fuse line.

Last night when doing the tests, I think I got amp results that fit. Running any two of three fuses, the amp going into the battery was about +1.0A and slowly dropping. This would make sense for a well regulated system connected to a charged battery. Ideally, once charge the amps would go to zero on the battery cable, but due to gassing and the like, it always stays positive.

Whenever I added the last fuse in, the voltage would drop, and the amp reading would to jump to +5 or so amps. Seems to fit what you just described would be occuring on a short to ground, or perhaps a more aptly described "leak to ground"?

So I'll be looking for a leak to greound somewhere from main fuse output tthrough switch to fuse bus? I have not problem replacing the two wires ging to and fro. But if it is a small leak to ground or intermittent leak to ground, it sounds like the ignition switch is the most likely culprit, yes?

Well, you need to measure the current on the fuse to see if it's increasing.

I would expect more blown fuses if the leakage was enough to kill the system.

What about weaking insulating plates in the ig switch. Under load, they could start to bridge a gap or allow current leakage, yes?

I still think its in the pig tail on the switch, I have seen them melted on the inside. I did take a switch apart once, took me forever to get it back together right, was a real pain

Really, a small leak to ground is possible anywhere. You need to look at how much current is going to each of the suspect sub-circuits and calculate which one may be drawing more than its fair share. Of course, start at the battery and work your way up to the fuses.

You can always measure the voltage at each fuse to see if there is a large voltage drop somewhere in the system.

At this point it's just a detective game of isolating where the current is going... fun stuff!

Knowing the current through each of the sub and main fuses in each case would be useful. The only way the numbers won't add up is if you have a leak to ground after the main fuse but not on any of the individual ones (perhaps the ignition switch), or if you have a load that's accidentally being powered by more than one fuse.

Its also possible that the leak is outside the main fuse (wiring or starter ?) That'd be easy to test - pull all the fuses & battery and measure resistance between + & - battery cables.

Ok after over 2700 hits and seven pages, What was the final outcome??

yeah, I can't believe how many times this has been viewed.

Currently, I took the ignition switch off. The plastic housing around the connectors were all cracked and very VERY brittle. The solder joints on the switch part all looked old and nasty, with more than one looking all dull grey like a cold solder connection.

I order a new switch which should be here by wednesday from Z1. Thankfully the electric part is removable from the mechanical part, so I'm using to use the old key part so I don't have to carry two keys.

I ran the bike last night using 12AWG jumpers for the connections the ignition switch would have made between the wires. The bike seems to work perfectly. I could rev it up to 14.5 V, but not 15.5V like before, because I think the battery is a little worn out. I will recharge tonight to get fresh and try again. 4 amps on headlight, 2.7 amps on coils, 2.6 amps on running lamps making total 9.3 amps running as expected coming out of main fuse. WEE!!!

Also, while waiting for switch, I replace fuse block with blade fuses and will install new block with switch. I'll post again after swtich installed, all buttoned up, and after a good long ride.

Hey all.

Replaced ignition switch as a module. Replace the plastic 6-position covers that connect the switch to the harness. I replaced teh existing glass fuse block plate with a blade/ATC style fuse block.

As best as I can tell, I'm good to go. The bike sounds like a dream now. At idle, it's about an order of magnitude quieter and smoother. My wife and I can ride and talk at idle without raising our voices. The on-tach voltmeter shows ~14 at highway run (I think it's probably closer to 14.8, the accuracy of the tach meter is debateable). I'm going to run on it awhile and see how it goes after some usage.

Really thanks so much. I have learned more about the bike's electrical than I thought was ever possible and I feel WAY more capable at fixing these problems too. Hopefully other people got some good ideas from this.

I'm thinking of making my own fault-finding chart based on the tricks we tried here that will help people determine problems across the whole electrical system without buying new parts unnecessarily. If anyone would like to comment or help edit, it would be greatly appreciated.