1200GS: The Faulty Fuel Strip Thread

Voltage DOES determine current - simple ohms law 1st year electrical.

On a given fixed resistance the higher the voltage the higher the current. Simple stuff, eventually you have fire.
and if you don't believe that, try the experiment on the bench for yourself.

Wait, I'm being greatly educated here and learning new fundamental principals of the universe! Wake George Ohm, Kirchoff and Einstein from the dead, they were all wrong!!!!!!!!!!!!!!!!!!!!!!!!!

Since "VOLTAGE DETERMINES CURRENT", as you say, WHY IN THE TIDDY HELL do you go on to state

???????????????????

I mean, resistance does not matter oh wise ones. Thats what you are saying because "VOLTAGE DETERMINES CURRENT"

SO DO ENLIGHTEN ME. Why are you saying anything about resistance?

Look, I'm bored. Do what you like, or better yet, don't do anything but type.

I can not get this through some of your heads with a truck load of 2X4s.

I have stated REPEATEDLY to use a current LIMITED power source with a short circuit current no GREATER then 20 mA.

If you can't understand that or what it means. Your loss, bye bye.

Don't get your knickers in a knot!
Sorry I missed the key word 'limited'
I thinks others did too
Obviously in a current limited circuit once the setpoint has been reached, additional voltage will have no effect until component voltage/insulation ratings are exceeded.

For other then those who understand ohms law wrongly.

http://www.allaboutcircuits.com/vol_1/chpt_2/1.html

<a href="http://www.flickr.com/photos/joel_wisman/6807444662/" title="Untitled by joel.wisman, on Flickr"><img src="http://farm8.staticflickr.com/7061/6807444662_a3052fcedd_s.jpg" width="75" height="75" alt="Untitled"></a>

Notice, "voltage over resistance determines current"



http://en.wikipedia.org/wiki/Ohm's_law

<a href="http://www.flickr.com/photos/joel_wisman/6953574053/" title="Untitled by joel.wisman, on Flickr"><img src="http://farm8.staticflickr.com/7062/6953574053_1a883ff130_s.jpg" width="75" height="75" alt="Untitled"></a>

Notice, "voltage over resistance determines current"


http://youtu.be/-mHLvtGjum4



http://hyperphysics.phy-astr.gsu.edu/hbase/electric/ohmlaw.html

<a href="http://www.flickr.com/photos/joel_wisman/6807491816/" title="Untitled by joel.wisman, on Flickr"><img src="http://farm8.staticflickr.com/7056/6807491816_da350a6405_o.jpg" width="483" height="171" alt="Untitled"></a>

Notice, "voltage over resistance determines current"


http://www.ndt-ed.org/EducationResources/HighSchool/Electricity/ohmslaw.htm

<a href="http://www.flickr.com/photos/joel_wisman/6807502144/" title="Untitled by joel.wisman, on Flickr"><img src="http://farm8.staticflickr.com/7057/6807502144_f8d31b086d_o.jpg" width="474" height="331" alt="Untitled"></a>


Voltage does NOT determine current. Voltage over resistance determines current.

Some of you are as right as you can get, this IS as fundamental as it gets in the world of electricity, so the fact that some you don't understand it is concerning since you are making statements of false fact on a thread dealing with electricity :)

In my suggestion of what may fix a fuel strip sensor circuit, I have made the following suggestion worded a bunch of different ways to hopefully get the message across, apparently without luck.

Apply around 1000 volts from a CURRENT LIMITED power source with no greater then 20 mA OF SHORT CIRCUIT CURRENT and no greater then 40 pF of CAPACITANCE.

This means we are dealing with two resistance values in series. One resistance is the fuel strip, around 2,700 ohm when working properly. The other resistance that is in series is the CURRENT LIMITED POWER SUPPLY!

I have stated repeatedly that this power supply should be limited to NO GREATER THEN 20 mA of SHORT CIRCUIT CURRENT.

This means, regardless of the load impedance and regardless of the voltage NO GREATER THEN 20 mA of current will flow because by whatever means, though usually fixed resistance, the power supply will NOT supply more then 20 mA at ANY voltage.

It does not matter what the voltage is at the power supply because current will NOT be following voltage because the power supply is LIMITED and as it happens, current is VOLTAGE DIVIDED BY RESISTANCE.


I am not going to get to which of the 4 pins on the fuel strip connector are the heater and which are the sensor, where the connector is, how you pull the strip out of the tank if you desire to, How you force the bike to recalibrate without a MOSS, how tight the fuel pump collar goes to prevent fuel leakage, why capacitance matters, or anything else because I have people vigorously asserting facts about current and safety that are basic, simple, and wrong.

Thats too bad, but this isn't my job, I'm not getting paid, my knickers are already in a knot and i have to get back to things more fundamentally important to me, changing the driven pulley oil seal on my scooter or sticking a battery in my caponord since its removed for Lead/acid versus LiFePo4 battery trials, so I can ride across town and eat.

Now, somebody play with a darn fuel strip instead of a keyboard and perhaps I will pop back in some day, but I need to get busy on other things before my knickers permanently knot LOL

I think what we all agree on is that theres a lot of wasted energy here!
But again I must disagree when you say "current will NOT be following voltage" ...It must..current is always the dependent factor. The Power supply will limit the current ONLY by lowering output voltage!!!! And your statement "the power supply will NOT supply more then 20 mA at ANY voltage" Is wrong simply by using the ohms law formulas you reproduced. Put your volt meter on your limited supply at 20mA and slowly reduce the resistance....and tell me the output voltage does not drop to limit current to 20mA!

All that aside, my only reason for commenting is to protect the the guy who posted the circuit that could potentially be unsafe. And when you questioned earlier about 1.08 watts, I will say yes, this is my main concern...If you know for sure that the strip will take that power for extended length of time, then there is no issue if the current is limited to the 20mA....UNLESS that 2700 ohms changes by a significant factor due to damage either by the arcing, or otherwise.

I'm prepared to end this discussion....
Thank you.

Sounds like you had a lively and dangerous childhood (not that I didn't play with gas myself from time to time)!

Great posts by the way. Thanks.

Sorry but i dont want you to mislead people... You cannot raise voltage without increasing current unless resistance is infinite and current is zero.

Apparently you are not prepared to end this discussion lol

Really? How about something like a tetrode? I can think of 10 instances where resistance is NOT infinite yet increasing voltage does NOT raise current but in a region actually lowers it, and thats off the top of my head without resorting to google or text books.

Ohms law, correctly stated as " I = E over R " has plenty of exceptions. Stating that " current follows voltage " is not even right half the time because it implies a linear relationship that rarely exists.

A simple incandescent lightbulb is a good example. apply a small amount of voltage and X current will flow. Double the voltage and the current will practically double. Raise the voltage more and you will not get a linear raise in current.

This is because as the tungsten element heats its resistance raises.

At any given instance in time, ohms law is still correct with a incandescent lightbulb, as correctly stated E over R is still in effect, it's just that R is changing.

Place emphasis on E being the driver, as in " current follows voltage " and you are lead astray because resistance is raising with current.

" current follows voltage " is something taught to people as a law when they aren't going to need to know much about electricity. It is a way of simplifying a complex subject. It is also WRONG, but right enough it needn't be corrected if people are just going to be scratching the surface of electricity, much the same as the current flow model versus the electron flow law.

Trust me, I know this is frustrating. While taking automotive classes I was taught that current flowed from the positive battery terminal to the negative battery terminal. Ok, simple, that makes sense, next topic... Later when I entered electrical, engineering and chemistry classes I found out that the current model is wrong. Electrons ARE the charge carrier and since they are negatively charged, they flow from the negative battery terminal to the positive battery terminal.

This isn't just semantics, you need to know the direction of electron flow for many many things to make sense, including why the chemical processes that take place in a battery take place.

As a technician, I didn't need to know these things. Put a battery tester on a battery, if it fails, the battery is bad...

As a field service engineer or electrician responsible for half a million dollars of UPS batteries, I needed to know the truth, because I had to understand the chemistry side of batteries to be able to remove the plates of the battery and determine what had damaged them. The chemistry of batteries does not make sense with the current model, it does with the electron flow law.

So, with all of that, electrons flow from negative to positive, ohms law correctly stated as " I = E over R " has plenty of exceptions, and the statement " current follows voltage " has more holes then swiss cheese and is a way of thinking that does not impress the correct way of understanding the dynamic that " at a given instance in time, " current flow will USUALLY equal voltage divided by resistance ". There is NO prime driver to simplify matters, voltage, resistance, and current are all interrelated.

Are you quoting "ELI the ICE man" when you state "current follows voltage". Thats capacitance my friend.

Even that statement is a simplification. More often correct is that " current will USUALLY equal voltage divided by IMPEDANCE " Because nearly every circuit in the world contains at least SOME inductive and capacitive reactance.

Explicit in all of this is that increasing voltage will not ALWAYS increase current.

My suggestion to use a " 1000 VOLT CURRENT LIMITED" power source with a short circuit current " NO GREATER THEN 20 mA " is one such instance.

Here is a typical diagram of an active current limiting circuit.

<a href="http://www.flickr.com/photos/joel_wisman/6957376839/" title="Active current limiting by joel.wisman, on Flickr"><img src="http://farm8.staticflickr.com/7055/6957376839_05a50bdbfa_o.jpg" width="202" height="313" alt="Active current limiting"></a>

Raising the voltage at the source will NOT result in increasing the current to the load beyond the threshold for which the current limiting circuit is set for regardless of load resistance unless of course you raise the source voltage beyond the level at which the circuit is designed to function.

You could also use a passive current limit where the source has enough resistance that with a source of 1000 volts, even were the resistance of the load zero ohms, not more then 20 mA would flow.

I am not suggesting anyone build their own current limiting circuit or 1000 volt source, though it's fine if you want to, but supporting such an endeavor is beyond the scope of what I had intended.

As a practical matter, it is easy to test current limiting. Hook the output across a multimeters current sensing probes. If less then 21 mA flows, I am suggesting we are good. If more then 20 mA flows, I am suggesting we are not.

Lastly, qman8. It is frustrating to be wrong, especially when you are repeating what you have been taught by others you believed to be right. I suspect this is what is happening, and have been in the same place myself. We could take this subject all the way to the quantum physics level, but it would not further the goal of this thread and likely bore a lot of people. Google is your friend as are text books :) Try googling the string "current does not follow voltage" and you will get plenty of hits and some good information.


The subject at hand for this thread is: "using a 1000 volt power supply, current limited to a short circuit current of no greater then 20 mA, not more then 1.08 watts will be dissipated by a 2,700 ohm fuel strip sensing circuit and if the fuel strip should happen to have lower resistance or a passive current limiting source is used, even less energy will be dissipated.

I am not insisting a 20 mA current limited 1000 volts power supply will be ideal for fixing the BMW fuel strip sensor circuit. I used exactly those figures on a fuel strip Volvo was testing out and nothing melted. With BMW I used a power source that had a measured 1 mA short circuit current and a measured 40 pF of capacitance.

IT IS JUST MY BEST GUESS that up to 20 mA of short circuit current from a 1000 volt power supply with no greater then 40 pF will be alright to hit BMW fuel strips with.. Thats just my best guess, but at least I have a good understanding of electricity

If you disagree that 1.08 watts can safely be dissipated by the fuel strip, this can be empirically proven using a fuel strip :)

If you disagree that a current limited 1000 volt power source with a short circuit current no greater then 20 mA will dissipate no greater then 1.08 watts into the fuel strip sensing circuit with a resistance of 2,700 ohms, at the least, show me some math so I can debate something other then your vigorous assertions :)

Holy crap! Caution anyone of you to allow this guy to work on your bike. I was prepared to end the discussion, but wrong info is just wrong info...Next you'll be running for public office!
Joel: I really appreciate your willingness to help the ADV list, and as a newcomer here I hate to say anything, but now you're really just spouting some wrong information. First you tout ohms law as your rock to stand on, then your cast it aside and say its not always true!??

A tetrode?? Cmon man...there's several independent circuits involved there and it seems like you're lumping them all together??

Capacative and inductive reactance? This is new here! I thought the whole time you were on a DC plane and were trying to leave LaPlace out of the equation?

Never did i say anything about vectored impedance(which still uphold ohms law), nor did I say that the I/V relationship was always perfectly linear. I said current was Dependent on voltage. BUT you are right when you said "
At any given instance in time, ohms law is still correct with a incandescent lightbulb, as correctly stated E over R is still in effect, it's just that R is changing" This is understood and I think it is what you are trying to say in the whole diatribe above...in so many words.
Also, Electrons really dont "flow"...they jump...its the charge that flows!!!
Your circuit shown is exactly what I was saying earlier about a current limited supply...and the whole idea is that the voltage across the LOAD does not increase. Certainly you must agree with me on this point, and is really how it relates to this discussion and a fuel strip as a "load".

Oh..and by the way i DID google "current not follow voltage"...and found that , yes, it really does!..among other facts..."Ohm's law holds for circuits containing only resistive elements (no capacitances or inductances) for all forms of driving voltage or current, regardless of whether the driving voltage or current is constant (DC) or time-varying such as AC. At any instant of time Ohm's law is valid for such circuits"

I fully agree with "a current limited 1000 volt power source with a short circuit current no greater then 20 mA will dissipate no greater then 1.08 watts into the fuel strip sensing circuit with a resistance of 2,700 ohms, at the least, show me some math so I can debate something other then your vigorous assertions"....ONLY IF you agree that there will NOT be 1000 volts across that fuel strip at 20mA.

This is pointless. The power supply is PART of the circuit, and if it is a CURRENT LMITED power supply with no greater then 20 mA OF SHORT CIRCUIT CURRENT, as I have been suggesting from the start. Spelled out as " You want 1000 volts 1 - 20 mA max current " in my very first post about this technique where " max " means under any conditions including short circuit, further clarified incase anyone didn't understand, a few posts down by " You want a short circuit current no greater then 20 mA at maximum. " then at some place in the circuit there is likely to be about 1000 volts that will pass through a resistance that, yep, to keep the current down to 20 mA will reduce output voltage that the strip sees down to 54 volts AFTER the break in the strip has been carbon tracked and the strip assumes a normal 2,700 ohm resistance.

Where in the tidy hell can you quote me saying that the voltage across the strip after it begins conducting will be 1000 volts or anywhere near it? How on earth do you think I arrived at the power strip dissipating 1.08 watts. Jesus this is 3rd grade math which you obviously know! Ohms law 54 volts times .020 amps equals 1.08 watts.

Please explain to me how someone that is obviously intelligent, can demand that I agree that " there will NOT be 1000 volts across that fuel strip at 20mA " when my figure for watts dissipated is 1.08 which is the product of 54 volts times 0.020 amps?


2 days ago, quoting YOUR post I stated this:

"Are you suggesting that a current limited power supply with a short circuit current of no greater then 20 mA will fall to a steady state of greater then 54 volts once the arc ends after creating a carbon track and powering into a 2,700 ohm circuit?"

I state the above, questioning if you understood that the strip is only going to see no greater then 54 volts once the strip begins conducting at its normal resistance of 2,700 ohm. YOU QUOTED MY FIGURE OF 54 VOLTS ACROSS THE STRIP!

How can a human that is communicating in good faith quote my figure of 54 volts across the strip and then demand that I agree the strip will not conduct 20mA at 1000 volts?


My formulas and statements have been the same since the beginning, though growing in complexity and detail. You qman8 are jumping around from item to item, never conceding but changing the substance of your argument when one of your statements is proved wrong.

In short, I am debating something I believe in good faith for the furtherance of the motorcycling community as you debate for the purpose of debate to try and hide that you got some things wrong.

When you qman8 stated:

" Wow...keystroke quantity impressive...but keep in mind that current is entirely dependent on voltage "

This made me think you were probably an idiot when it comes to electricity. Not simply because you were wrong, but because your arguments keep changing.

I considered responding:
"Really, what is the current 0f 1000 volts since you are stating that current is ENTIRELY dependent on voltage? What is the current of 54 volts?

Since you are stating that current is ENTIRELY dependent on voltage, resistance can't matter, otherwise current would only be PARTIALLY dependent on voltage."

But instead, in good faith, I attempted to politely inform about how your statement was wrong.

Later I Inserted the part about ELI the ICE man because I felt you might be confusing capacitance with resistance, seems hard to do but anything is possible. This was a polite statement in good faith that we are trying to exchange knowledge. Your response is the clincher:

" Capacative and inductive reactance? This is new here! I thought the whole time you were on a DC plane and were trying to leave LaPlace out of the equation? "

No one that understands the terms you clearly understand or is intelligent enough to know what LaPlace refers to could ever construe my statement about ELI the ICE man as anything other then what it was, and yet you have, deliberately.

You qman8 are behaving like an ASS and doing absolutely NOTHING for this topic or community.

If you were simply an idiot, I would suffer you, but you are clearly smart. This means that for the sake of pride or a desire to disingenuously debate, you are jacking this thread while being insulting and derogatory to me.

Please go away.

So for a layman...

Let's say I somehow make sense of the procedure, and have access to the equipment to do it...

...and I get a broken strip from a cooperative dealership, and do the procedure...

Is there a way for said dealership to do a diagnostic test on the treated strip w/o having to reinstall it first?

Yeah, and you can yourself with a multimeter which is all the dealership uses to check the strips.

It varies some with different models and years, but a good strip will have from X to X resistance in the heater circuit and from X to X in the sensor circuit.

I don't remember the precise numbers and year breaks, but will see if I can dig them up, but also, if you happen by a dealership, they likely have a cheat sheet stuck to the wall cause any decent sized dealership measures these resistance values several times a day.

I have no idea what either one of you are talking about but it was entertaining for awhile, no so much now. Could you please start throwing insults back and forth?

In the basement about politics I will go all day! This is supposed to be science lol

Electrical Engineering bitch slap fest forum now