Basic electrical

[850 Combat]

Thanks.

Thats what I thought. I think I'm going to begin some upgrades.

Very late and need to sleep so a quick attempt at the last two posts.

A fuse or breaker is intended to open, or stop the current flow in a circuit if the current flow reaches the set point of the fuse or breaker. This would typically be because of a decrease in circuit resistance rather than an increase in voltage so same Voltage/smaller Restance = more Amps. Higher current (more amps) times same Voltage = more Watts, so higher power factor than that for which the circuit was intended and smoke.

Installing a larger fuse would allow a larger current flow before the fuse controlled the circuit so smoke for sure if something went wrong.

When considering a VRR of larger capacity (designed to service a larger capacity alternator output) the rectifier bridge will be capable of carrying a larger current so will be less challenged by the smaller load to which it is actually attached.

In addition, regardless of the regulator type (assuming a permanent magnet alternator) the regulator's capacity to shunt current to ground will be greater than for the smaller alternator so, again a greater margin. If one of the SCR or other circuits, the regulator will be at least as capable as needed.

An additional consideration which seems to be largely ignored is that of the forward bias voltage drop in semi-conductors. Diodes, for example, which are used for rectification in most alternators as electrical one-way valves allow current flow in only one polarity as everyone knows. What few seem to appreciate is that common silicone diodes have a no-load forward bias of about 0.7 volts which rises to over 1 volt at full load.

Yep, put a diode in series and you must expect a voltage drop (loss) of a volt or so. We had not end of problems with travel trailers, motor homes, service trucks and boats in which electronic battery isolators were installed. Seems like a great idea as there are no moving parts but knock one volt off your 14.6 volt charging voltage and see what happens to the time required to re-charge a battery! You can time the charging with a calendar!

Put 20 amps through a pair of diodes (one postive and one negative) and that requires a voltage drop of 2 volts. No big deal, you say as the regulator simply dials up the alternator voltage to compensate. Yes, that's correct but you also have at least 40 Watts of heat from the rectifier alone in that VRR box. The voltage regulator will contribute more.

The VRR intended for the larger alternator will be designed to dissapate the heat from a higher rectification current so will be happier when dealing with a smaller output.

Hope that explains.....

Norm

[Normk]

Thread length is irreverent as long as it's productive.

irreverent

[Smellii]

haha. autocorrect. irrelevant

[Smellii]

Finally sat down to read this thread. Thanks, Norm for your time to do this. I'm certainly more knowledgeable as a result. Bridging the gap between theory and application I'm curious what might one physically change in the bikes electrical system to compensate for each of the properties being off. Say for example when adding some electrical component to the bike and resistance is to high or low or voltage to high or low. Am I thinking to hard or should a properly functioning stator/rr automatically compensate within their specified limits?

Also, could I trouble you to explain exactly what resistance is? Where does it come from and provide some motorcycle examples? As far I as I know it's simply a measure of how imperfect the path between two points is. So the resistance between two ends of the same wire should be low (good) but rather the resistance in the point of connection of two different wires would be higher (worse). So the more connections in a system the higher the resistance and could be compensated by higher voltage? If this is an accurate understanding you don't need to dive into great detail in your response.

[Graham]

Basic electrical?

[Normk]

"Am I thinking to hard or should a properly functioning stator/rr automatically compensate within their specified limits?"

The voltage regulator limits voltage to a design set point. This is to say that the regulator reduces the alternator output when the voltage begins to rise above the intended voltage. The typical set point varies but is in the range of 14.2 to 14.6 volts for most older vehicles. Some GM products went into the 14.8+ area and some newer vehicles stop charging altogether for periods of time as a fuel saving technique but that's getting off the motorcycle subject area.

The alternator makes as much as it has magnetism, stator windings and engine RPM allow and the regulator acts to limit output if the voltage begins to exceed the setting.

In this way the system automatically compensates for different loads as you stated.

Your explaination of resistance is a workable one if we are reading in the same context. Connections my have higher resistance than the conductors which are being joined however the intent is that the connections do not have a significant difference. We suspect high resistance to be most likely resulting from a problem within a connection because a mechanical connection is more susceptable to corrosion.

I like your use of the term "measure of how imperfect the path between two points is". Mrs. Knott, my Grade 3 teacher, would have whacked my knuckles for dangling that participle but other than that I will attempt to steal the phrase.

It's 11:30 PM and I've been short of sleep for the last while so am fading quickly. Will try to get back here in the morning to see if have mucked this up badly.

[Normk]

I posted this elsewhere but it cannot hurt to place it here also, make a trip to your local "Pick-a-Part" self serve auto wrecker and buy a handfull of relays for projects. While you're there, get some bulbs with sockets and buy a wiring harness off any car.

The wiring harness can often be purchased for a few dollars and is a gold mine of color-coded wires, connectors and handy stuff. Rather than wiring all your accessories with the same white, red, blue and black wires from spools of wire, select a blue with green tracer for one, red with yellow for anther, etc. Record the colors on your wiring diagram and life is easier.

Dig out some of those bulbs and sockets for some electrical system education. It may be time to move to some hands on but not sure as there has been little feed-back as to whether anyone is trying the suggested activities.

Grab some sockets and bulbs of the same bulb number and confirm that each bulb is about the same brightness by connecting each across a battery. Next, connect two bulbs into parallel by placing two bulb sockets across the battery, side by side.

Both bulbs light to the same, normal intensity. Either bulb will light without the other being connected. Both bulbs are supplied by the same voltage as is evident from the connection but you can confirm with your voltmeter.

This, parallel connection, is the most popular means of connecting lights and other components on a vehicle. Various circuits connect in parallel from the main wiring harness so that each circuit can operate without interference or dependence on others. This allows the tail light to operate without being dependent on the headlight or dash lights, etc.

If you have an ammeter, place a fuse of lower capacity to your meter's maximum current in connection with one battery connection and use the fuse as the connection for experiments in case an error is made. An error will thus blow the fuse and not cause damage to the meter (we are hoping!).

Ammeters are risky tools to use unless one keeps one's wits on line. Placing a voltmeter across a power source will cause the voltmeter to indicate the voltage (push) between the two sample points.

Placing an ammeter across a power source such as a battery, without some limiting device, can cause the power source to deliver the maximum surge of current of which it is capable. This may damage the meter.

Connect one ammeter lead to the fuse and then connect one wire from a bulb socket to the other ammeter lead. Connect the other bulb socket wire to the other battery terminal. Does the bulb light?

Does the ammeter indicate a current flow value?

If so, things are connected with fuse, ammeter and bulb in series across the battery. Series means that the components share one path for current flow.

Next, connect another bulb socket's two wires to the same wires on the installed socket. This light is in parallel with the first light but both are in series with the ammeter and fuse.

What happened to the magnitiude of the ammeter reading?

Assuming that you are using small bulbs such as #194 "peanut" bulbs, the ammeter should still be a long way below its maximum capacity. Let's assume that your meter can handle 10 amps. maximum current. You should be around 2 amps. with both bulbs connected.

Note that the bulbs are both fully bright as though each were operating independently, because they are independent despite being connected to the same power source.

Add another bulb and what happens to the operation?

Next, take that third bulb from the circuit and insert it between the ammeter lead and the other two bulbs. What happens to bulb brightness & ammeter reading?

Are the three bulbs illuminated to the same brightness?

Why?

I will try to make time to post some diagrams later today if time allows. A couple of friends are dropping by for help with different projects so...

Some feedback as to whether anyone is trying experiments would be helpful and as to whether this is still helpful and on topic.

[Trevor76]

Hey Norm, I am barely into this thread (way back on page four) but already feel the need to say "thanks"...

I'll continue to read through this in my free time when I'm awake and coherent enough to absorb information.

[Normk]

Speaking of relays: suppose you find a relay but don't have the circuit diagram. Most "Bosch type" have the diagram with pin #'s on the case which is great but otherwise?

If it has four connections, it is most likely that two connect to the magnetic winding while the other two go to the switched contacts. The problem is that some relays use a common positive terminal to provide power to both the load (switched contacts) and to the magnetic winding which is grounded in order to operate the relay. This requires only three connections. The other can be a normally closed switch contact which will burn out if one simply experiments by connecting to a battery.

The method generally use is a test light connected between the battery and the terminal being tested. In this way there is sufficient power to operate the relay but insufficient current flow to burn out contacts.

I like this as a means of testing diodes....maybe posted that earlier in this thread...

Off to sleep, 'night all!

[Normk]

The thread "voltage drop at the tail-light bulb" may be of interest. Posted a piece relating to the VRR sensor wire location.

On another subject relating to this thread, there was a mention of the use of Schottky diodes here or on another recent electrical thread. Schottky diodes have a very low forward bias voltage which seems attractive as compared to silicone diodes. I wondered at the time as to why these aren't used in rectifier bridges and did some research by reviewing the Schottky listings in the Mouser catalog. Schottky diodes only have the very low forward bias voltage with small/tiny current flows. A significant load such as that in a rectifier application pushes their forward bias voltage up into the silicone diode range 1 to 2 volts. It was an interesting excercise as I learned something about Schottky applications but will likely forget it all soon.

Time for some lunch and then vacuum the house.

Just noticed a charging system diagram which Cliff posted so will see if it can be captured and add some labels for some more discussion on trouble shooting and voltage drop measurement.

[Normk]

No recent activity here so don't know if anyone is still following?

Haven't heard any voltage drop values either so asking again if some will take measurements between the end caps of the fuses in the main fuse box and the brass fuse clips. This needs to be done with the key on and the circuit switched on.

The fuse box shown in the illustration is obviously not connected but simply used to illustrate the meter lead connection.

Could we also have some voltage values measured between one fuse clip and battery positive with engine running and all loads on. Headlight high beam?

It's hard to break the ice on this activity but it can be very beneficial for those who are trying to get started so how about some of the old hands stepping up with values.

Mine are: 1979 GS850G with standard wiring excepting for an HID headlight and bar heaters. The HID and bar heaters are both powered through dedicated relays so load on the original wiring is lower than for a stock bike.

Fuse clip to fuses vary between "0" and a few milli-volts.
Voltage drop battery positive to fuse box 0.863 volts

Step up please! When we get some values coming, others will contribute and maybe some of those wanting a start in electrical testing will be empowered.

[playswithnitro]

Hey Norm,
Have just read through this whole thread: Thank you.
Bloody well done.

[Killer2600]

Ok class test on this stuff on Friday

I'm curious how many people are more visual and have spent time on youtube learning various electrical topics? You know the people who rather watch the movie than read the book.