Basic electrical

[bccap]

How about if someone posts an electrical problem. It doesn't matter if the " how to " is in another section of this site. Its the why that matters. If we can understand that then we'd be on the road to trouble shooting. I'll start it by asking about the ten dollar rectifier Norm posted. I don't understand this rr concept. Do we need to install a separate regulator, and then wire to the rectifier, or just this one part ? There. I've displayed my electrical ignorance. Can someone explain both the concept and the solution ?

[Normk]

OK, 10 minutes before leaving for son's soccer game so let's post a start.

The multimeter....switch(es), several sockets and other choices.. how to make sense of it? The problem with electrical is the double path required in learning. One has to learn to use the instruments combined with making sense of how to apply the readings....oh, and figuring out where & how to connect which overlaps with the other two. Sort of like a three phase alternator.

First rule with a meter is to never, never switch from one scale/setting to another with the leads connected to anything. If you switch from volts to frequency, for example, both will be OK but crossing through Ohms, Amps., diode test, etc. can result in damaging the meter so don't ever do that.

My Mac meter has blocking which prevent the leads from being plugged into the wrong plugs after a setting has been selected but can't prevent switching damage afterwards.

Another rule is to always start on the highest scale setting and work down if you don't know for sure what value is present.

Volts will simply show over scale so it's unlikely to damage the meter if you stay on the volts settings but connecting Ohms or Amps. (milliamps, microamps, etc.) to power is likely to be nasty!

Time to go but pull out your meter and find the three main scales which are used, volts, Ohms, and diode test. Let's avoid any of the amps. settings completely for now as these are risky until you are comfortable with your meter.

Off to soccer game, HIH

Norm

[tom203]

How about if someone posts an electrical problem. It doesn't matter if the " how to " is in another section of this site. Its the why that matters. If we can understand that then we'd be on the road to trouble shooting. I'll start it by asking about the ten dollar rectifier Norm posted. I don't understand this rr concept. Do we need to install a separate regulator, and then wire to the rectifier, or just this one part ? There. I've displayed my electrical ignorance. Can someone explain both the concept and the solution ?

The ten dollar special needs a regulator after it, cuz all it does is rectify. Great for someone who likes to tinker, but I just want a reliable total charging solution, so I will scoop $10 used Shindengen R/R's off ebay and find other ways to challenge my old brain.

[Normk]

For $10.00 to buy a complete VRR it would not make sense to adapt a Delco rectifier unless one wished to challenge their old brain.

If one has a failed rectifier, one could adapt the Delco rectifier to work with the Suzuki regulator.

Here's the short explanation regarding the regulator, rectifier and alternator but keep in mind that it is simplified to a fault.

As everyone knows, moving magnetic lines of force through a conductor, parallel to the path of the conductor generates a voltage. If there is a complete circuit, a current flow will result.

OK, when I said, "short explanation" keep in mind that I try very hard to make explanations as complete as I can so that someone reading can understand the logic of the subject.

Let's consider placing a line of marbles onto the groove in one of those old fashioned wooden rulers. The marbles are touching one another in a line and represent the electrons in a conductor. Placing ones finger against the further marble and facing the nearest, one can look along the line of marbles. If one leans down and blows against the marbles, parallel to the groove in the ruler, the air pushes against the marbles and the marbles each press forward against the next marble until the further marble presses against ones finger. The harder one blows, the more pressure against the finger but the marbles don't move because the finger is blocking their path. The line of marbles will exert more pressure against the finger because the wind is pushing against the series which add to the pressure. Simple picture, I hope.

OK, so we have moving air, pressing against marbles which press against the finger. The amount of pressure against the finger can be felt so we have an indication of the pressure.

This is a similar effect to that of magnetic lines of force from the rotor of your motorcycle's alternator. These magnetic lines of force "press" against the electrons in the wires of the alternator's stator and try to make the electrons move. The harder the magnetic lines "press", the more "pressure" which the electrons exert in attempting to move.

We might express the pressure against the finger in ounces or pounds but in electrical measure, we use volts or voltage as the measure of electro-motive force.

If you refer to the recent thread in which someone is testing their alternator and VRR (voltage regulator/rectifier) you will read the reference to the measuring of stator voltage with engine running at 5,000 RPM with the stator disconnected. What is being tested here is the voltage (pressure) which is being exerted by the alternator rotor's (the hockey puck shaped magnetic center driven by the engine) magnetic lines of force acting on the stator wires. If the alternator is functioning properly, the lines of force from the stator magnet should push against the electrons in the stator wires with sufficient force to produce over 70 volts of electrical pressure between each pair of the three wires leading from the stator. If you place three dots in a triangle, you will note that the dots can be connected in three pairs.

OK, so what is being tested? The volt meter is measuring the push being exerted by the turning rotor through the magnetic lines of force from the magnets. You will also notice that the wires and magnetic don't know which ones are turning and which ones are not but only that the magnetic lines of force are moving in relation to the electrons.

What if we used a water hose to direct water against the marbles at the same speed as the air which we were blowing? The marbles would be pushed harder so we would feel more pressure against our finger, right?

What if we blew the air at a faster speed? More pressure.

OK, so if we make the media doing the pushing against the marbles or the electrons more dense, the push will be harder, correct?

This follows whether we are pushing marbles with air or water = harder push, or whether we are using a stronger magnetic field to push electrons = more voltage.

Oh wait! We just noticed something obvious! The air can be all around the marbles but there is only a push if the air is moving relative to the marbles. Marbles could be placed on the hood of ones car and driven throught the air which would push on the marbles, or the air could be blown against the marbles...same effect. In other words we need some thing to push air/water/magnetic lines of force, something to push marbles/electrons, and to have relative motion between the pushing thing and the pushed thing.

Instead of using a thicker "pushing thing" such as water, we could also move the air faster to the same effect.

OK, remember the alternator test? They were measuring the voltage (push) but the engine needed to be running to get the magnetic lines to push but it had to be running at around 5,000 RPM so that a certain amount of push against the electrons (voltage) was expected to be exerted by the magnetic lines moving at a certain speed.

We would expect there to be less push if the engine were turning slower but the specifications are given at a certain speed to make a certain voltage, otherwise we would need pages of speeds and voltage references so this just makes it simpler. Two numbers to compare.

Let's look at the discussion: the voltage (push) measured from the stator wires is less than expected, a lot less.....what could be the problem?

One obvious one might be that his tachometer isn't working so, as he said, he is guessing as to the speed. Could that explain the low voltage?

Not likely as anyone will be able to estimate when the engine is running at about 1/2 of full speed, and regardless, the voltage measured is really low. It's as though the engine is running at only a fraction of the 5,000 RPM and he's not going to miss that so we need to dismiss that possibility.

OK, the pushing effect is moving at the expected speed but not giving the expected voltage, let's consider the next of the three components of the "pushing thing", "thing being pushed", and pressure...hope I'm still using the same terms as just typing this off the top of my head. Actually it's the first time I've tried this analogy so see if it works out.

What if the media doing the pushing isn't as dense as it should be?

Time for supper so more later,

Norm

[Normk]

Ok, if the media doing the pushing wasn't as dense as it should be, as we have seen, the "push" won't be as great so that would result in a lower pressure/voltage. Well, that's the problem so how does that relate to the alternator?

The pushing media/stuff is the magnetic field or magnetic lines of force created by the rotor magnets. Weak magnets would result in less push. Obvious? Yep!

So something which caused the magnets to become weaker would result in less "push", resulting in lower voltage measured at the stator output leads. That follows easily.

Some impact, degaussing from a magnetic field, or impact on the rotor could do that.....what else?.....time! Time could do that too, especially if the magnets are of lesser quality. Oh, oh...how do we check to see if the magnets are weaker than they should be? That's a tough one as no magnetic field density figures are published for motorcycle alternator rotors and, even if they were, we have not accurate means to measure.

What to do? Well, failing other possibilities, we can hold that possible cause in mind in case we exhaust others but that's not very satisfying and kind of humiliating to go to a customer with that....

One way is to assume that alternator magnets are similar in strength and to compare the effort needed to pull an iron/steel tool from the magnets to be compared. Over the years we have been able to confirm that several rotor magnets were weak and replace with good results but the other side of that diagnosis was the elimination of other possibles.

What about other causes....?

One obvious issue with the ruler and marbles is the effect of changing the angle of the ruler. If we had placed the ruler and marbles onto the hood of a car and driven around, we would have noticed that the push against our finger would be the same at the same air speed. If we were driving in still air, the push would be the same as driving faster with the wind and slower against the wind. So how might that compare to the stator?

Almost trapped myself with that analogy but, here's a relation: If the ruler is tipped so that the finger end is higher, more air speed or thicker media is needed to provide the same push against the finger. If there is a fault within the stator wiring which increases the effort needed to move the electrons, then the same media at the same speed will produce less push/voltage. If there's a bad connection, that will give the same effect.

This is why two of us posted to suggest that he ensure that the connections and wires were in good condition and to test with the least lead-in wiring possible. The other poster was quicker on the draw than I.

What about if we removed some marbles? The area on which the moving air can act will be less so the same media at the same speed will result in lower "push"/voltage. Take out some marbles, or allow some of the loops of wire to become joined so that the over all length of the wire/ruler is less and less voltage will result. This could happen if some of the stator coils were shorted together due to an insulation fault.

A definition for you: in trade terms a "short" is an electrical related term referring to a "short circuit" or on other words, a circuit which has a shorter electrical path than is intended. In this terminology the electrical path does not follow the intended route and so problems with the operation of the circuit occur. Usually the main problem is that things start to smoke and (hopefully) a fuse blows to stop the electricity.

People mistakenly refer to a broken circuit path in which the current path is interrupted or opened as a short but this is the opposite condition. An "open" circuit is one in which the path is disconnected so no current flows.

His stator could have a short circuit, so how could we relate that?

A short circuit would explain why the correct media density at the correct speed isn't pushing the electrons as strongly as to produce the expected voltage (pressure). Let's think about that.....

Check out the Stator Papers to look at the voltage values for the stator windings. I haven't looked at these for some time but check any permanent magnet stator diagnosis and you will see the same information for checking the stator.

There three measurements for the stator, why? Somewhere you will have seen references to "single phase", "three phase", and likely that the GS alternator is a three phase. This means that there are three, overlapping paths (ruler grooves) in which electrons are pushed by the rotor magnet.

The three phase windings each connect to two output leads so that the three output leads each have two different stator windings connected. I'll do a diagram or link one but suffice it to say that we need to test between each combination of two leads.

OK, someone says, let's grab the Ohmmeter. Ohmmeters are a waste of time for checking low resistance circuits, forget them for this purpose. Someone will likely wish to dispute this but save both our time as it is cast in concrete, ask any electrical technician.

Going back to our analogy, we test the resulting push which is accurate and at high RPM should be 70+ volts between each of the three stator leads. What if one reading is low, or two, or all three?

A stator is sold and serviced as an assembly so, unless you want to really tax your old brain, you will have to buy a good one.

Next, onto the rectifier, sorry you asked?

Norm

[Normk]

You will have noticed that the procedure for checking voltage between the stator leads always specifies using your voltmeter on the AC scale. Have a look at your meter and note that it will have some means of switching between AC (alternating current) which comes from household wall plugs, alternator stators, pick-up coils (electronic ignition & ABS brakes, etc.), charge coils, that kind of stuff; and DC or direct current which comes from batteries, solar cells, muscle control nerves and spark plugs (sort of...).

Our bikes and cars use DC current because batteries can only make and be recharged by, current which flows only in one direction, called "Direct Current" or "DC" current. Don't ask why we say "DC Current" but not "Direct Current Current" because I asked and was told not to ask, so I don't ask and you can't either.

If you want a longer explanation, I can explain why we use AC current (don't ask that either!) generators on vehicles rather than DC current ones like in the old days.

Alternators (AC generators) are simpler is all we need to know for now.

The problem is, we can make AC but need to convert it to DC so we need some device. In the old days we would need to use an AC electric motor to turn a DC generator to convert AC to DC but now we can use several types of electronic devices, loosely called diodes. We refer to a diode or diode set which are used to change AC to DC as a "rectifier".

Diodes are electrical one-way valves which allow current to pass in one direction but not in the other. They are sort of like a reed valve used in many two stroke dirt bike intake systems. Like reed valves, diodes cause some restriction to flow which can be a problem.

A simple rectifier is one diode placed into the circuit while a more efficient circuit, called a "diode bridge" is composed of four diodes.

In a simple charging system such as used on many small motorcycles, there is one stator winding which connects at one lead to the engine and the other to a wire leading to the rectifier.

The GS has a three phase system so we see three wires which lead out to the rectifier. Look up a three phase rectifer on the net or (I am sure it is in Cliff's linked Stator Papers) to see the diode symbol (an arrow pointing to a vertical line) and the arrangement of the six diodes in the three phase rectifier bridge. Think that I wrote papers on the three phase bridge on My-Mc, DSN_KLR650, Wings on the Internet, and likely some other places so will not do it again here at this time. Better to go look and see if you can follow the current flows in the rectifier. Find one which is separate from the regulator, print it out and take your pencil to draw arrows in the direction of current flows when each stator phase is producing current.

OK, so short explanation, we have a set of rotating magnets in a rotor which moves its magnetic lines through the three phases of the stator windings which produces AC voltage. No current because there is no path for current to flow from one end of each stator winding to the other end. What we have is the maximum voltage (push) which the moving magnetic field can produce when not electrons can move because our finger/the disconnected output leads provide an open (no path for flow) circuit.

Let's hook it up to the rectifier, start the bike see what happens now!

First, we measured more than 70 Volts AC between each pair of the three stator leads when the leads were disconnected so let's see what we get now! OK, we know that the battery needs DC so let's switch our voltmeter to DC and measure between each pair of stator leads.....zero volts!

What gives? The alternator must be charging because the lights became brighter when we started the engine or is something else happening?

Switch the voltmeter to AC and check...oh, maybe 20 volts AC between the legs, yes, that makes sense because the stator makes AC, not DC!

Now switch back to DC and check the battery voltage.....14.2 volts. Shut the engine off and the battery drops to 13.2 volts. On with the lights and then shut off and the battery voltage is 12.8 volts. A normal, full charged battey will show between 12.6 and 12.8 volts depending on temperature and the area in which you are located. Not going there right now either.

More next post... don't you hate the dreaded "text you have entered is too long, please shorten to 10000 characters."

Norm

[Normk]

If the battery can only produce 12.8 volts but the voltage goes up above that with engine running, the alternator must be stuffing electrons into the wiring to raise the pressure. It must be working, at least to some degree.

OK, let's go get that Delco Remy 10SI rectifier I mentioned on another thread. It has a six diode bridge and will connect to our three stator leads to convert three phase AC to DC. It will also handle many times the amount of current which our puny bike alternators will produce so no problem there!

OK, hooked up and engine started. Stator voltage (AC scale) is about the same so switch to DC and check the battery voltage. 18.5 volts and rising! SHUT DOWN!!!

What the "H", "E" double hockey sticks is happening!!!

Remember the bike part is a "VRR", while this Delco Part is a rectifier or "VR"? Voltage Regulator/Rectifier versus Voltage Regulator!

Sort of like a chicken salad sandwich versus a raw chicken salad sandwich!

OK so what's the cause of the voltage going so high with the VR versus the VRR?

Our alternator produces current, remember, because we have a circuit connected to allow the electrons which are being pushed by the rotor's moving lines of force. The stator wires stay the same. Same size of stator wires, same number of windings so always the same push...oh yes, same push at the same speed! Same push, same voltage at the same engine speed, same engine RPM!

When we connect a circuit the work being done by the voltage pushing the electrons (current/amps.) remains about the same because the engine is pushing the same magnetic lines against the same number of electrons in the same stator windings. The only thing we can change is?

How hard we push/how fast we turn the engine.

If we restart the engine and let it slow idle, the voltage is low but OK, as we gradually speed up the engine, the voltage climbs and climbs until we start to see nearly 15 volts and wisely slow it down.

Let's think about how we use the engine. If it were a water pump, it would always run at the same speed so if we wanted to run a light, we could connect a small generator which pushed electrons just hard enough (just enough amps @ just enough volts = just enough watts) to power the light nice and bright. Slow the pump motor down and the light would become dimmer...but we don't run the pump slower so no problem!

OK, so now we buy a bicycle to ride to and from our night job watching the water pump by the glow of our light. How to get to and from work when it's dark?

We install a small generator which is driven by a roller against the tire. First time we ride, we notice that it takes some effort to pedal with the generator going..more work to make light requires more work to pedal but the kit we bought has a headlight and tail light so we can see and be seen. When we are going faster the lights are brighter and slower the lights are dimmer but that's OK because we don't need to look as far ahead when going slower. Does this sound like the logic used by British vehicle engineers? Being Welsh, I wonder...but I digress

All is well until, one night while riding to work we reach down to adjust the headlight and knock the wires off the light. Digging our trusty flash light out we ride to work and decide to fix the wires by the light of our trusty water pump. All the time watching for the boss so not to get into trouble for failing to watch the water pump.

After a bit of fiddling the wires are connected and we try a test. Headlight works! In fact it seems even brighter than before! A genius!

[Normk]

Riding home a car almost hits us from behind and the driver rolls down a window to shout, "Get a tail light, idiot!"

"Wow, better check that when we get home. Maybe we knocked those wires off too?"

All the wires seem to be OK so remove the tail light bulb and, using our trusty Ohmmeter, find there is infinite resistance. Not path for current, open circuit, burned out bulb. Off to the bike shop to buy a new bulb.

Complaining to the shop owner that we have only had the kit for a couple of days, he responds, "Did you disconnect the headlight while riding?"

How did he know that? "Well.... yes.."

What happened?

The bike generator was sized to produce enough Watts (amps pushed by enough volts) to power the headlight + the tail light. When we disconnected the headlight, there was a smaller bulb left connected which had a smaller capacity path for current. Since we had the same generator speed with the same magnetic field, fewer electrons could flow so there was a "bottle neck" and the push (voltage) became higher until so much current was flowing through the small bulb (maybe 18 or 25 volts instead of 10 to 14 volts pushed twice as many electrons) making twice as much heat in the filament and poof! Burned out.

So now we think back and recall that the headlight was brighter after we repaired the wiring....Hmm, the headlight was disconnected so the voltage went up so high that it pushed too much current through the little tail light bulb and burned it out. When we repaired the wiring, we had no tail light working because it had already burned out which was why the car driver didn't see us. The headlight was a bit brighter because the load of the tail light was gone so the generator increased voltage and so current flow through the headlight. The headlight would stand the small increase in heat for a time but would have its live shortened.

Back to our GS. We can idle the engine and run at lower RPM so long as we have the headlight on without making the voltage go too high but if we turn off the headlight, the instrument bulbs all burn out.

We also can't ride with the engine RPM up in the normal range or the voltage goes too high and headlight soon burns out. What to do?

We could disconnect one of the stator leads which drops output to about 1/2 which allows us to ride at full RPM but the voltage still goes too high if we turn off the headlight and at lower RPM the light is very dim. Not the solution.

This similar to the problem with many of the little old scooters and small motorcycles, dim lights at low engine speed and bright with the engine rev'd up.

In order to make things practical, the manufacturers have installed a voltage regulator which only happens to be included in the same "box" on most motorcycles. It doesn't need to be in there, just easier to make and install.

The early regulators (these units are all voltage regulators which is incorrect terminology because they don't regulate the voltage but that's for another time if someone asks) I'm betting that few have made it this far!

The early regulators which can typically be seen as fins poking out beneath the lower fork triple tree on old Nortons, Triumphs, etc. use a Zenor Diode to limit voltage. These semi-conductor devices have a threshold voltage at which they begin to conduct current.

If one wanted to limit the maximum voltage to 14.5 volts, one would install a 14.5 volt Zenor Diode which would be connected in parrallel with the battery/alternator output. When the bike is running at low RPM, nothing happens with the Zenor but when output from the alternator becomes too high that the voltage reaches 14.5 volts, the Zenor begins to conduct current to ground. It acts like the spillway on a dam. When the water level becomes too high, spillway takes the additional volume to prevent the level/voltage from going higher.

Modern systems us more sophisticated circuits but the effect is the same. These allow an alternator to be fitten which can produce enough power at low engine RPM to satisfy loads without allowing the output to drive voltage too high at higher engine speeds.

This type of voltage regulation, or more properly, voltage limiting is typical of permanent magnet alternators as fitted to motorcycles, ATV, outboard motors and such. Automobiles, trucks, heavy equipment and higher end motorcycles such my Honda ST1100, which has a 60 amp alternator (about 875 Watts), use a controlled field alternator. These alternators vary the strength of the magnetic field in order to control the output.

I can explain the operation of these if anyone is interested.

HIH, although I type this off the top of my head and don't edit (pardon the spelling and typos) it still requires significant effort so I don't care to do this if no one is interested. Let me know if this type of article is useful and whether the "chatty" style is prefered or if straight tech. talk is preferred.

I'm also pleased to discuss concepts and interpretations but have a short fuse for rudeness as I'm doing this for free. People have been good about jumping in to help me with compute issues and such so what goes around comes around which is great.

It requires little effort in reading web groups to confirm that few technicians care to post into their areas of expertise so if their presence is appreciated, take care not to drive them away.....

Norm

Too many images complaint....

[Hoosier Daddy]

I hate to interrupt but thought you should know... You Sir, have the patience of a Saint! BRAVO!

[alke46]

I read it all and can appreciate the time you took to explain it all fully to us with no electrical training. Thank you for your time and input even though some of it went over my head like a screaming rocket.

[Normk]

Let's hear whether a longer article such as posted is the best or whether small, how to is most desired.

Here's a small one. Dig out your multimeter and find the Volts range of settings. Does your meter have several settings? Or does it just have one volts setting on the switch?

Does your meter have a selection to choose between AC or DC?

All of these questions are basic to meter use and are part of the baby steps to getting up to speed. Like most things, once you get moving, things come faster and faster.

If your meter has only a volts setting, then there must be another means of switching between AC and DC, find that.

OK, let's assume that your meter has only volts settings for AC or DC with no means of choosing the maximum voltage to be measured. That means that your meter is most likely an auto ranging one. Some of the meters which allow a choice of range will auto range but let's consider the implications of the ranging.

When you turn your meter on and switch to volts, select DC and are thinking of checking something such as the batteries from a flashlight which is going dim, or that TV remote which doesn't work, or maybe your bike's charging voltage, you will need to consider the expected voltage which you will measure. The bike's system makes just less than 15 volts maximum with the flashlight and remote less than that.

OK, when you touch the test leads to the battery, the meter will indicate the voltage sensed between the leads. Nothing new there, right?

What can be confusing, very confusing, is that the meter may indicate a higher number when the leads are not touching the battery than when they are. Try setting your meter to DC volts, if it has choices for voltages, set the scale at the range which is just over 15 volts (say 20 if that's the choice) and touch the leads to the battery. What do you see?

If you see 12.8 then you are seeing a fully charged 12 volt lead acid battery. But when you remove the leads, maybe the meter says 134, so what's going on? Have a close look at the scale and you will likely see a symbol such as mV, or milli, something like that.

What is happening is that the meter is auto ranging. It has automatically switched to a lower voltage scale in order to display the voltage which it sees in whole numbers. It is sensing, maybe, 134 millionths of a volt from magnetic effects out of the air. That's the 134! This can drive you to distraction if you are checking something which has an extremely low voltage, for example because the auto ranging switches down and displays a bigger number because you didn't notice the scale change.

Don't feel foolish as we have all been bitten by that when checking and not thinking about the meter display.

What about other scale settings?

Let's say that your meter allows you to select ranges such as 100 mV, 1 V, 10 V, 20 V, 100 V, 1 kV, 10 kV. OK, so how to start?

Remember the meter rule that someone has likely told you, "Always start measuring with a meter setting higher than the expected value to be read."

If we don't know the voltage to be encountered, we set the above meter at 10 kV (10,000 volts) and take a measurement. Hook it to your bike battery and it displays? Zero, unless it is an auto ranging in which case it will set down. Let's assume the meter doesn't auto range.

Nothing, zero on the display so, disconnect the meter leads, set to 1 kV (1,000 volts) and test. Keep going until you see a meaningful value. Try it on your bike and some batteries around the house.

OK, "I've tried all sorts of things but get meaningless numbers! What now?"

Have a look at the meter again, does the display say "AC" or "DC" Volts?

If it shows "AC" then it is likely to show silly numbers because it is likely auto ranging down to the 1/1,000 volt or 1/1,000,000 volt range and picking up induced voltage from the air. You may have to dig out the book or just have another look to see if the switch needs to be set to another area (AC voltage ranges are usually grouped in a separate area than DC).

Nothing lost here as you have now noticed that the meter will auto range down on AC also and find meaningless numbers so you won't be surprised to see that happen when you are working. Switch to DC and try some measurements again. Write them down but don't worry much about what they mean as we will get to that later.

Try this one for fun: take a penny and a quarter, wet a piece of paper with saliva and place it between the two coins. Measure the voltage with one meter lead on each coin. What voltage do you read?

Let's see a few numbers indicating voltages read from your bike battery, and some other batteries around the house.

Have you noticed that your meter shows a "-" sign sometimes beside the value? How about a "+"?

The meter expects that the red test lead be plugged into the meter's "+" (positive) or red socket and the black lead into the "-" (negative) or black socket. It also expects to encounter a polarity of postive at the red lead, negative at the black.

How your meter reacts is something you will need to know. Most modern digital meters simply switch polarity automatically if you have the leads in the opposite polarity but a few will show and error message or some other indication that you need to reverse the leads.

Knowing how your meter shows polarity is like having money in the bank as it can save you from hooking up that expensive GPS in the wrong polarity and letting out the smoke.

I'll leave it here for now until we see some feed back.

Let me know how this is going for you as I can shift gears to another area or try another tactic if that is more useful. Do dig out that meter and play around. As long as you avoid the scales other than volts, you are extremely unlikely to do harm to anything.

Once we get you up to speed to measure some values, we can move to Ohms, Amps., etc. Stay away from those scales if you hook the leads to power as you may let the smoke out of the meter.

HIH

Norm

[Normk]

I'm willing to work on this with you but need feedback as to where my attempt went off the rails. Keep in mind that I am trying to present the subject so if it's not on target, I'm the one missing the aiming point, not you.

Someone commented in another post that I need to get a thicker skin. Not going to happen. I am not prepared to volunteer time and take pooh and don't expect anyone else to be different. If something I write seems to show disrespect it is being misread because I crafted it poorly. Please PM and let me know how it went wrong so that I can clear the misunderstanding.

I have taught several hundred college trades students to use meters and to make electrical measurements but that is an easier prospect than doing so over the net to people who haven't even met. It is an extremely challenging and interesting problem which is what I get out of the process. That and my Mom taught me to try to help nice people.

Norm

I read it all and can appreciate the time you took to explain it all fully to us with no electrical training. Thank you for your time and input even though some of it went over my head like a screaming rocket.

[keman]

Sounds like you are on the right track. I know it can be a lot of work. I have done my share of teaching in my industry. I know it can seem like taking to a wall sometimes.

[koolaid_kid]

I've been reading your posts, and I agree some feedback would be nice. As a EE and a former teacher, it can be frustrating when the students just stare back at you.
However, you make some valid points about the auto-ranging meters. I don't like a machine making decisions for me, and I want to be able to set the range I want. (It's a control thing.) I much prefer a meter that lets me set the range, and I like ones with auto-off. I occasionally forget to turn it off, and replacing the batteries can be a pita. Just a thought.

[bccap]

Am following closely, and for the most part understanding. Will reserve questions til you are through the rr test, where I do have a question re stator paper tests.