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Old 21-07-18, 07:56 AM   #81
Yellow650Loz
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Default Re: Erratic ignition now no power, no start

Quote:
Originally Posted by Seeker View Post
With DC they use the whole conductor, with AC; the higher the frequency the more they migrate towards the surface skin of the conductor.
Someone was listening in their physics lessons
In practice though, theres no such thing as a perfect conductor.
Yeah, as the frequency increases the charge density increases and the electrons are observed at the surface of a 'Perfect' conductor.
However in DC vehicle applications we use stranded 'flex' as this increases the total surface volume, reducing the need for massive solid core cables. Obviously there's the requirement for it to be flexible also.
I love a good physics discussion, but it doesn't help the OP
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Old 21-07-18, 09:31 AM   #82
SV650rules
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Default Re: Erratic ignition now no power, no start

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Originally Posted by Yellow650Loz View Post

You had so much right and changed your mind for the summary [IMG]file:///C:\Users\Comet\AppData\Local\Temp\msohtmlclip1\01\ clip_image001.gif[/IMG]
If a connector gets corroded it will cause a higher resistance.....this will drop the VOLTAGE at the load which will increase the current drawn......please see ohms law for ref.
As the current increases this will increase the temperature of the corroded connector and further increase the resistance.
The amount of heat that can be physically conducted back to the R/R is miniscule. I won't say it can't be conducted back but if I heat just the tip of a length of say 14AWG wire to solder to, or get it cherry red.....20CM away from that point will be ambient or close to. Either way it's negligible. Consider that diodes are generally ok just over 70 deg c, if they weren't then the processor I'm your computer would fail about 10 seconds after switching on.
Having said that, as the old proverb goes. A candle that burns twice as bright lasts only half as long; yes, the hotter something runs, it's working lifespan will be reduced but we're talking about an R/R it's designed to run that hot.
The R/R is doesn't try to compensate, if the voltage drops below 13.5vdc with the lamps on high beam at 5000rpm then it's out of spec; or the charge systems components are unsuitable for the current load required. This is the reason the stator was upgraded on the injection bikes to circa 300w IIRC ...... Its got more electrics to run and therefore more load. The only thing it will do is stop feeding so much current and waste this off as heat.



I lost the quote bubbles somewhere along the way so I've underlined my annotations, perhaps if I ask very nicely....a mod might clean it up for me [IMG]file:///C:\Users\Comet\AppData\Local\Temp\msohtmlclip1\01\ clip_image002.gif[/IMG]

SV650rules I hope this helps you as well as the OP or anyone in the future reading this thread.
Not helped at all…………………….
You are having a laff right ? if you increase resistance anywhere in a circuit and voltage stays the same current is always going to drop (see Ohms law I = V/R if the numerator stays the same (V) and the denominator gets larger (R) the value of result (I) has to get smaller. You are making the mistake of keeping the 'wattage' at the load at eg 55watt, and sure enough to maintain 55watt at a lower voltage the current would have to increase (W-V*I) but as the voltage drops that 55watt bulb will just get dimmer, and while the number on the bulb may still say 55watt the bulb will not produce 55 watt of light because it is designed to be 55watt at 12.5 volts.


Quote:
Originally Posted by Yellow650Loz View Post

AC and DC work differently, with an AC system we deal with higher voltages in order to use solid core wherever possible. Electrons move over the outside of conductors with only a few exceptions and so the surface area is greatly reduced, thus can handle a lower current.
AC has more of a tendancy to arc due to the magnetic field created, I won't go too far into this as it isn't relevant to the OP, the first discharge lamps were DC and VERY unreliable due to the high current required to create the arc, AC ballasts are far more reliable and so the lower current draw is far more forgiving on it's components, especially within the discharge capsule.


If the 55 watt bulb is replace with a standard resistor with fairly flat resistance / temperature characteristics

I presume you mean using a resistor with 5% tolerance.....one with a gold band?

It is only at pretty high frequency you get a ‘pipe’ effect with electrons where they tend to use outside of conductor, at 50Hz no probelmo ( they use solid core cable for normal domestic wiring). The reason a solid core is used in house wiring and not in machinery and vehicles is that solid cores tend to break when they are subject to movement and vibration, where stranded ‘flexibles’ do not’.

The tolerance of a resistor has nothing to do with whether it has a low or a high positive or negative coefficient of resistance, it is all down to what it is made from – when I said a standard resistor it was ‘a standard resistor that is designed (as they are) to not change resistance much as it got hotter or cooler’ (which is the opposite of a bulb filament the resistance of which changes massively as it heats up).

Actually DC has more of a tendency to arc than AC, simply because an sine wave (AC) passes through zero volts once every half cycle ( every 10mSec at 50 Hz) as it transitions from positive to negative – this will quench any arc (an arc cannot exist without voltage), DC only passes through zero volts when it is turned off, so once an arc is established there is nothing to quench it.
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Last edited by SV650rules; 21-07-18 at 09:36 AM.
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Old 21-07-18, 10:56 AM   #83
Yellow650Loz
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Default Re: Erratic ignition now no power, no start

Not helped at all…………………….
You are having a laff right ? if you increase resistance anywhere in a circuit and voltage stays the same current is always going to drop (see Ohms law I = V/R if the numerator stays the same (V) and the denominator gets larger (R) the value of result (I) has to get smaller. You are making the mistake of keeping the 'wattage' at the load at eg 55watt, and sure enough to maintain 55watt at a lower voltage the current would have to increase (W-V*I) but as the voltage drops that 55watt bulb will just get dimmer, and while the number on the bulb may still say 55watt the bulb will not produce 55 watt of light because it is designed to be 55watt at 12.5 volts.


Might I suggest you're beyond help then
If you increase the resistance in a circuit the voltage will drop. This isn't a textbook mate, the drop in voltage will cause a higher current draw.
It's 55w nominal, that's what it's rated at...... you're struggling to get this, I won't keep explaining how this all works in the real world. When you mess up the electrics on yours, let me know....I'll buy it





It is only at pretty high frequency you get a ‘pipe’ effect with electrons where they tend to use outside of conductor, at 50Hz no probelmo ( they use solid core cable for normal domestic wiring). The reason a solid core is used in house wiring and not in machinery and vehicles is that solid cores tend to break when they are subject to movement and vibration, where stranded ‘flexibles’ do not’.

The tolerance of a resistor has nothing to do with whether it has a low or a high positive or negative coefficient of resistance, it is all down to what it is made from – when I said a standard resistor it was ‘a standard resistor that is designed (as they are) to not change resistance much as it got hotter or cooler’ (which is the opposite of a bulb filament the resistance of which changes massively as it heats up).

Actually DC has more of a tendency to arc than AC, simply because an sine wave (AC) passes through zero volts once every half cycle ( every 10mSec at 50 Hz) as it transitions from positive to negative – this will quench any arc (an arc cannot exist without voltage), DC only passes through zero volts when it is turned off, so once an arc is established there is nothing to quench it.

Again, I won't repeat what I wrote. I have a job to do
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Old 21-07-18, 11:49 AM   #84
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Default Re: Erratic ignition now no power, no start

@Yellow650Loz

https://www.amazon.co.uk/Basic-Elect.../dp/0471850853
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Old 21-07-18, 12:09 PM   #85
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Default Re: Erratic ignition now no power, no start

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Originally Posted by Yellow650Loz View Post
If you increase the resistance in a circuit the voltage will drop. This isn't a textbook mate, the drop in voltage will cause a higher current draw.
I'm not sure where you've got this from, if the voltage across a (relatively) fixed resistance load drops, the current will also drop.

With a corroded connection, it's effectively an additional load in the circuit. Because of this, there's a voltage drop across it and therefore power consumed which must be dissipated as heat.

The easiest way to diagnose a problem is to check the voltages between the battery, R/R and load and either side of connectors between. In a perfect world they should all be the same. If there's a significant difference between any two, then your problem will be between the two points. The Haynes manual (if I remember correctly) gives acceptable voltage differences.

The same applies to the earth. A garage once needlessly replaced the starter motor on my car because they swore it was dead as they could see a voltage on it. It turned out that the earth bonding was shot and it was just the clutch cable providing a path back to the battery -ve.
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Old 21-07-18, 01:16 PM   #86
glang
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Default Re: Erratic ignition now no power, no start

I wonder if some of the confusion is coming from this: Although simple electrical items like lights, heaters etc consume less current with a lower voltage across their terminals some more complicated items like induction motors do actually draw more amps to maintain their power output.
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Old 21-07-18, 04:24 PM   #87
Yellow650Loz
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Default Re: Erratic ignition now no power, no start

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Originally Posted by daktulos View Post
I'm not sure where you've got this from, if the voltage across a (relatively) fixed resistance load drops, the current will also drop.

With a corroded connection, it's effectively an additional load in the circuit. Because of this, there's a voltage drop across it and therefore power consumed which must be dissipated as heat.

The easiest way to diagnose a problem is to check the voltages between the battery, R/R and load and either side of connectors between. In a perfect world they should all be the same. If there's a significant difference between any two, then your problem will be between the two points. The Haynes manual (if I remember correctly) gives acceptable voltage differences.

The same applies to the earth. A garage once needlessly replaced the starter motor on my car because they swore it was dead as they could see a voltage on it. It turned out that the earth bonding was shot and it was just the clutch cable providing a path back to the battery -ve.

you've just said the same thing, It's effectively an additional load on the system. However it also creates a problem on both sides, the component being supplied the power in the first place will have a reduction in voltage.
It's rated at 12v however Suzuki designed the system and the wiring to run at 13.8v curvy or 14.9 pointy IIRC.

Im sure the OP said a starter motor was used alot; because the bike wouldn't start, it would start to overheat the circuit, it's not designed to be used like that, eventually the weak link would be found. In this case the connector. Was the connector actually found to be rusty? Or just melted? I can't remember or mustav skipped that page
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Old 21-07-18, 05:26 PM   #88
SV650rules
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Default Re: Erratic ignition now no power, no start

Quote:
Originally Posted by daktulos View Post
I'm not sure where you've got this from, if the voltage across a (relatively) fixed resistance load drops, the current will also drop.

With a corroded connection, it's effectively an additional load in the circuit. Because of this, there's a voltage drop across it and therefore power consumed which must be dissipated as heat.

The easiest way to diagnose a problem is to check the voltages between the battery, R/R and load and either side of connectors between. In a perfect world they should all be the same. If there's a significant difference between any two, then your problem will be between the two points. The Haynes manual (if I remember correctly) gives acceptable voltage differences.

The same applies to the earth. A garage once needlessly replaced the starter motor on my car because they swore it was dead as they could see a voltage on it. It turned out that the earth bonding was shot and it was just the clutch cable providing a path back to the battery -ve.
+1

Although the corroded connector should probably be described as 'an extra resistance' rather than 'an extra load' - but I understand that you mean a load in the sense that work is being done at that point by the current flow, the unwanted resistance caused by corrosion of the contact faces will cause extra work (heat) at that point. Second law of thermodynamics basically says 'All energy ends up as heat'

On every car I have owned I have fitted one of these braided leads between battery negative terminal and engine block, I do not trust all those small rusty connections between body and engine...

https://www.halfords.com/webapp/wcs/...ch=earth+braid
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Last edited by SV650rules; 22-07-18 at 09:16 AM.
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