Topic: Will I make it home (battery)

[bggann]

 
Little worried.  Road in to work today with new Dyna 1s (stock coil) and new starter button.  Couple of places had to stop and start the bike and each time the starter went slower and slower - last one (Napa), furget it.  Kick start.

It appears my battery is getting drained as I ride - why??? Was having no problem before this.

So - 2 questions.
Does a Dyna 1S with STOCK Coils pull a lot more power from the battery (searched and did not see that).

What pulls more/less power.  High beam - or low w/running lights. (relevant to getting home).

I have a 25 mile ride - some 50/50 city highway to get home....

BG

[andy750]

Switching your lights off is the best way to save on power. I had a battery go bad on me while out and switching off headlight helped (if you dont have that option on your switches then consider unplugging it from inside headlight - if its a legal/safety issue then keep the rpms up (above 3000 rpms usually charges the battery...). Id kick start it and try and not use indicator lights (hand signals only).

good luck!
Andy

[bggann]

Yeah - I was thinking about doing this.  But stupid me - for some reason I left the tool kit off the bike yesterday.  The battery is 4 weeks old - so I'm thinking it is charging system/ignition related.  I didn't think the Dyna 1S with stock coils would pull much more - I'm saving money up for the 5 ohm Dyna Coils.

[andy750]

I agree about the Dyna S/stock coils - I have the same setup and have had for years and 10,000s miles with no charging issue. Id check your battery level (distilled water) - could be dry? If not perhaps a bad battery? Connections?

cheers
Andy
 

[TomC]

Hi Bggann
     With a stock 35/50 headlight it is a toss up as far as current draw between low and high beam. You can turn off the head light and running lights by pulling the headlight fuse. The Dyna with stock coils will draw more current that stock because the coils are turned on for more of each cycle. How much more? I would like to know too. I am running 55/60 headlight and my guess is the Dyna does not pull that much more current. But as I do not have a working starter switch I do not know how much using the electric starter drains the battery.
Hi Andy750
     Remember we are talking about a CB400F here. Your CB750 has a more powerful alternator.
     TomC in Ohio

[andy750]

Hi Andy750
     Remember we are talking about a CB400F here. Your CB750 has a more powerful alternator.
     TomC in Ohio

Ah yes good point!! Thanks for reminding me.

cheers
Andy

[bggann]

Well - did (make it home) - even started it (once) with the starter, but now that it is running well (see my other post), gunna have to dig into the charging system....

[tom8Toe]

Please... keep us posted. I'm curious to find out what the issue is as I'm experiencing the same problem with my 400/4 after replacing my regulator, rectifier, fuse box, wire harness and stator unit and still haven't been able to identify the problem.

Regards,
Chris

[TomC]

Hi Bggann & Tom8toe
     I had an idea as I riding my CB400F1, if you ride mostly during the day just unplug the lights in the tachometer and speedometer. The wire is brown with a white tracer. There should be a y-connecter in the bag of wires. My guess is two wires need to be unpluged. Bggann I would be surprised if your Dyna draws that 14 watts over the stock set up. 14 watts is what the four bulbs should draw.
          TomC in Ohio

[bggann]

Clever idea TomC.  Lots of people talking about brake lights, tail lights, etc - nobody thought of those instrument lights.  It would be a simple switch to add.

Thanks!
BTW - I charged the battery last night and today to/from with no issue.  I'm going to ride a few days - it may be I had the battery way down because of all the work I've been doing.  Lots of sitting there with the headlight on while idling. 

I did clean some connections as well - but I haven't really spent any time diagnosing.

Bob

[keiths]

I always thought there was only one bulb in each gauge, until one burned out. I still only run one bulb each to save some power. There seems to be plenty of light.

[TomC]

Hi Bggann
     Putting a switch in the instrument light circuit is in my plans. Once the battery is down it's either put it on a battery charger or head out on the highway. There is not the extra power to recharge a down battery.
          TomC in Ohio

[TwoTired]

I worked up this power budget for a 500/550 some time ago, to illustrate how the charging system and bike treat the battery.  Except for the headlight, it should be pretty similar to the 400F.
Understanding electricity is largely a numbers game.  Here are some for you to ponder.

Stock CB 500/550 electrical budget.
Alternator output - 110 watts at 2000 RPM , 150 watts peak, about 40-50 watts @ 1000 RPM

50 W -High beam   Headlight
3.4 W -High beam indicator
8W    -tail light
27W    -Stop light
16 W  - 8 W x 2 Front run lights
13.6W    - 3.4 W X 4 Instrument lights
49.4W     -23 W X2 turn signals plus 3.4 w indicator
28.8 W - maximum for ignition  (when points closed, one at a time, this is the stock 5 ohm coil power draw.)
196.2 W -total maximum drawn from battery

600W  -Starting motor

--- Minimum lighting ---
40 W -low beam Headlight
8W    -tail light
16W  -8W   x 2 Front run lights
13.6W   - 3.4W X 4 Instrument lights
28.8 W  - ignition estimate  (points aren’t always closed)
106.4W -total  (normal electrical draw from battery)

Battery capacity is about 12v x 12 AH or 144 Watts (for about an hour, sort of)

Example:
Weak battery has about 20% power  (Est.) Needs  (115 watts + 20% charging efficiency loss) or 138 watts to fully charge battery.

Alternator output - 110 watts @2000 RPM, 150 watts at 5000 RPM
If you don’t use turn signals, high beam, horn, etc. And you keep the engine @ 2000 RPM minimum, then 110W – 106.4 W = 3.6 watts going to the battery  (about thirty eight hours of driving.  Or, @ 5K RPM 43.6 watts go to the battery (about 3.1 hours of driving).
The bike charging system is designed to maintain batteries, not charge severely depleted ones. But, if you drive long enough with enough RPM, it will do it.
Only excess power made by the alternator and not used by the bike’s electrical system is available to recharge the battery.

Note that 1157 bulbs are 27/ 8 watts instead of the 23/ 7 watts Honda used during manufacture.  If your bulbs or other lighting have been replaced or “upgraded”.  You’ll have to adjust the above budget numbers.

If you know your battery is low, keep the RPM up, to keep it from going lower.  Anything electrical you can switch off will extend its usefulness.

To check your charging system, monitor you battery voltage in 1000 RPM increments.  When the voltage trends higher, you are charging the battery.  When it trends lower, particularly lower than when the bike even isn't switched on, then your battery is depleting.

Electronic ignitions may not use the same coil on times as the points provide.  The manufacturer should know what on time or dwell time they have designed their unit to provide.  Call them and ask.  If it has a longer dwell time, it will deplete your battery faster, whenever the alternator can't keep up with the demand, and reduce the power available to recharge the battery, making recharge slower.

A 5 ohm Dyna coil will NOT use less power than the stock Honda 5 ohm coils.

Cheers,

[TomC]

Hi TwoTierd
     "Or, @ 5K RPM 43.6 watts go to the battery (about 3.1 hours of driving)." I agree a tank full at highway speed gets thing nicely charged up. But if you do not have any were to go a battery charger makes more sense.
     550 alternator output. From the Shop Manual Honda CB500-550. Page 95 says Output 150W no rpm specified. Page 136 Three phase A.C. 12 V-0.2KW / 5,000rpm. Page 138 Three Phase A.C. 12 V-0.11KW / 2,000 rpm. Page 166, Supplement to CB550F, Three phase A.C. 12V-0.11KW / 2,000 rpm. Page 171, Supplement to CB550 K2 ('76), A.C. Generator 0.13KW / 2,000 rpm. Page 181, Supplement to CB500 K3 / CB 550 K3 ('77), A.C. Generator 0.13KW / 2,000 rpm. Page 189, Supplement to CB 550 F2 ('77), A.C. Generator 0.13 KW / 2,000 rpm. you list "Alternator output - 110 watts at 2000 RPM , 150 watts peak, about 40-50 watts @ 1000 RPM" From my measuring of the output of the alternator of my CB400F1 I would say that an alternator producing 110 watts at 2000 rpm should put out about 200 Watts at 5,000 rpm. As to peak output, I would think that there would be some increase in output with increased rpm so that peak would be at red line. If the voltage regulator did not cut in first. Have you checked the output of the alternator of a running CB550? Has anyone else? Your figure of 40-50 watts @ 1000 rpm. Was that an actual measurement?
     TomC in Ohio

[TwoTired]

Hello TomC,
I agree there is some spec confusion within the Honda data sources.
I don't agree that the alternator generating efficiency is linear with RPM increases.  In fact, I believe it loses efficiency above 5000 RPM, and that is why it is spec'd for a peak at 5000 RPM. It is capable of less power production at 9000 RPM than it is at 5000 RPM, due to magnetic field change lag and less time to reach the magnetic peak field strengths at those higher RPMs.  Lesser RPM specs show that it is less efficient/capable at lower RPMs.  This is because there is more than enough time to achieve saturation, but the frequency of the phase change is lower, so there is less power delivery due to the fact that the peak magnetic field collapses and is fully reversed in a shorter time than is available for that phase, at that given RPM.
Because of production variables, not all factory alternators will produce identical power at RPM.  Winding lay, wire insulation thicknesses, the permeability of the rotor material, and the mechanical proximity between rotor field and stator coils all factor into the power production capability of each specific unit.  Further, the stock rectifier changed from germanium diodes to silicon diodes. Making the later slightly less efficient than the germanium when new.  Perhaps this was a factor in earlier units spec'ing higher output. (speculation)

I've not noticed any change in design, of the alternator components proper, from the 500 model to the last 78 550 model.  I've not done destructive testing, nor have I tested each one for power production capability.

My last actual power delivery testing was quite some time ago.  What I learned was that the table on page 94 of the 500/550 Honda Shop Manual was correct, with the exception that they omitted the minus sign for numbers in the 1000 RPM column, and I didn't get quite the drain at 1000 RPM that was stated in the book.  I think mine was about 4.5 or 5 amps battery drain at 1000 RPM.
Since a the stated 6.5 Amp power drain equates to a 78 watt drain on the battery, and the bike consumes 106.4 W whenever the key switch and lighting are enabled, simple subtraction indicates the alternator providing only 28.4 watts at 1000RPM.  So, I was being generous at 40-50 Watt estimation (which I probably recalled from a 750 alternator calculation.)  Perhaps the book spec 6.5 A drain was set this way to keep Honda shop mechanics from replacing good alternators?

Finally, the wattage consumption numbers I posted used a fixed Voltage. I used 12.8 because the lamps are all spec'd for power consumption at that voltage.  They all consume less power when given less voltage.  In fact, the whole bike consumes less power at lower voltage.   I didn't recalculate all the wattages consumed at 12.6V full battery voltage or 12V for a depleted battery, or the wattages at 13.8v or 14.5v, either.  It's a sliding scale, and I felt the extra listings would clutter and further confuse readers.

Does this sufficiently answer your questions?

Cheers,

[TomC]

Hi TwoTired
     I did not expect that generating efficiency would  be linear with increasing rpm. But I find it surprising the alternator output would not keep increasing past 5,000 rpm.
     The CB550F parts book shows the alternator parts with 323 numbers, CB500. I wondered if there was a later set of parts.
     As to using a fixed voltage to make calculations. I suppose you could do a table with different voltages, but why. The only current draw I question is the turn signals. Assuming there is sufficient current to get the flasher to flash, remind me to fix the ground on the left front turn signal, this current will only be drawn part of the time. I expect the amount of time out of the cycle that current is flowing varies to much to come up with a percentage.
     My question really was does the 550 alternator produce more power that a CB400F1 alternator. As I have measured about 160 watts output from the alternator of my CB400F1. The answer is does not look like it. I have a 1977 CB550 K3 that I have not heard run and should hear run. I will check it's alternator output one of these days and compare it with the alternator output of my CB400F1.
     Thank You for you answers. TomC in Ohio

[TomC]

Hi TwoTired
     Another alternator output question. If say I have an alternator that produces 150 watts at 5,000 rpm. Will the alternator only put out that amount of power at a certain load or different loads? Say 12Volt X 12.5 amps or 15Volts X 10Amps.
          TomC in Ohio
Hi TwoTired
     After I logged off and walked out the door I realized that there would be about a 3 Volt difference in the field voltage. Clearly that is going to reduce the power output of the alternator. I think that some voltage below the voltage were the voltage regulator cuts in say 14 Volts would be my standard for testing alternator output.
     TomC in Ohio

[TwoTired]

Hi TwoTired
     I did not expect that generating efficiency would  be linear with increasing rpm. But I find it surprising the alternator output would not keep increasing past 5,000 rpm.

DC generators have a more linear-like power output.  Alternators, not so much.  Particularly the SOHC 4s without slip rings, as the rotor magnet power is induced rather than directly energized by a winding for each specific pole piece.  The alternator charging output pulses (six of them)  Are sinusoidal.  They rise from about .7 V to peak value in a rising then falling arc.  As the rotary speed changes, the distance between the pulses become narrower, so more pulses in a given time frame occur to increase output power.  At idle, the pulses are a farther distance apart, so there is less time when the actual voltage output is above 12V than when the engine is reved up.
The induced magnet strength of the rotor gets weaker at some given RPM (I expect 5000), above which point there is not enough time in the magnetic field of the coil to attain maximum pole piece strength.  I suspect this is why Honda evolved their charging systems to Slip rings for the 650 versions. And permanent magnet types in other models.

     The CB550F parts book shows the alternator parts with 323 numbers, CB500. I wondered if there was a later set of parts.

I don't think so.  I've not encountered any.

     As to using a fixed voltage to make calculations. I suppose you could do a table with different voltages, but why. The only current draw I question is the turn signals. Assuming there is sufficient current to get the flasher to flash, remind me to fix the ground on the left front turn signal, this current will only be drawn part of the time. I expect the amount of time out of the cycle that current is flowing varies to much to come up with a percentage.

The stock signal flasher starts on and won't interrupt current flow until enough power is drawn to bend the bimetalic strip in the flasher.  When the voltage gets low, the lamps come on but don't blink, because the bimetallic strip never gets enough heat.  So, the duty cycle of the signal lamps can be 100% when the battery is low.  If you put in a flasher of a different type, (besides adding another unknown variable to the calculation), you can reduce the signaling drain to whatever your flasher provides.  50%???  But if you still have the turn beeper, you still have to add that current during the off time of the signals. (whatever that is)

     My question really was does the 550 alternator produce more power that a CB400F1 alternator. As I have measured about 160 watts output from the alternator of my CB400F1. The answer is does not look like it. I have a 1977 CB550 K3 that I have not heard run and should hear run. I will check it's alternator output one of these days and compare it with the alternator output of my CB400F1.

I have not measure the 400F output.  But, given the electrical resistance parameters, and the relative size of the power producing components, I would expect the 400F to be slightly weaker on average across production samples than the 500/550.  It would not surprise me to learn that some 400F alternators made more power than some 550 alternators.  But, most, I expect, would not.
The spec numbers in the books are not absolute. It should be a minimum spec.  In order for vendor samples to meet spec and still have a production tolerance, most will work slightly better than spec. Say it is determined that a given recipe for making alternators has a 10% variability. Then you must alter the design to average 106% higher than spec.  Some alternator samples will then provide 116% of spec, and some will only provide 101% of spec.  But, none of your manufactured components should land in the scrap heap by design.  Only if the build recipe is altered.

     Another alternator output question. If say I have an alternator that produces 150 watts at 5,000 rpm. Will the alternator only put out that amount of power at a certain load or different loads? Say 12Volt X 12.5 amps or 15Volts X 10Amps.

Watts law is I x E = P.  The voltage and amps measurement are directly relational. But, I must caution you that these numbers are delivery measurements and are highly effected by demand.  To attain the max power output you must have enough circuit resistance to allow for max delivery.  Further, if you place too much circuit resistance on the Alternator, the sinusoidal peaks cannot reach full excursion before being depleted.  This will appear to look like an an out of spec unit if not tested correctly.  Like with a connected battery as a buffer to the load resistance.

     After I logged off and walked out the door I realized that there would be about a 3 Volt difference in the field voltage. Clearly that is going to reduce the power output of the alternator. I think that some voltage below the voltage were the voltage regulator cuts in say 14 Volts would be my standard for testing alternator output.

Absolutely correct!  The field voltage has direct influence on alternator output capacity.    The Honda shop manual shows 14.5 V as the full battery voltage cutoff.  But, guess what? Another complication is that to prevent overcharging the battery, the regulator purposely reduces the field voltage, thus reducing alternator output.  Generally this means the alternator cannot supply the bikes total needs and the battery begins to deplete.  At some point the regulator notices and turns the Field back to full until the battery again reaches 14.5v where the cycle repeats.   The frequency of this switching depends on vehicle resistive load, physical plate size of the battery, and the reduced power output magnitude of the alternator.  (more calculations!!!).  The trap, here is the test equipment chosen for monitoring.  Analog meters deflect at the average DC level.  So, it probably won't see a 14.5V peak.  It will see something less, even though there is an AC component riding on the DC level.  Digital meters may not be much help either, for they not only average, but they sample in very small time increments, that are unlikely to coincide with oscillation rate of the variable regulator cycling.  Digital meters can also have a display update rate than can differ from the sample rate AND the Regulator cycle frequency.  This all leads to what is called aliasing, where the displayed measurements are not actually a true representation of circuit activity.  And it is something to be alert for when checking DC circuits that have AC elements introduced.
I think a lot of people would be surprised if they looked at the charging system component connections with an analog oscilloscope.

Hope this helps your investigation.

Cheers,

[TomC]

Hi TwoTired
     Thank you for your response.
     Both from what you say and my last attempt to measure alternator output the next time I try to measure my alternator output I will bypass the voltage regulator and use an adjustable load. If I am comparing my CB400F1 with my CB550K3. I will adjust the rpm and the voltage to be the same and compare the currents. I will be interested to see if there is a difference at lower rpms, 1,000 to 2,000. In looking at the specifications for the 400 & 500/550 alternators the field resistance is almost the same but the stator resistance is quite a bit different 400 0.61 to 0.69 ohms and the 500/550 0.35 +- 10% ohms.
     Thank You TomC in Ohio

[TwoTired]

Hi TomC,
In looking at the specifications for the 400 & 500/550 alternators the field resistance is almost the same but the stator resistance is quite a bit different 400 0.61 to 0.69 ohms and the 500/550 0.35 +- 10% ohms.

I don't recall looking at that.  Probably because the 400 I had didn't have any charging issues.  The 400 must use a smaller diameter wire to get the required number of turns in the smaller stator physical size.  If you suck the same power from both, the 400 will run at a hotter temp.  Common practice is to derate the output to keep temps inline without self damage.  Lower temps are equated with higher reliability.

10 amps through a .69 resistance loses 6.9 volts, and 69 watts.
10 amps through a .35 resistance loses 3.5 volts, and 35 watts.

Cheers,

I wonder how many readers out there have glazed eyes?

[alltherightpills]

I wonder how many readers out there have glazed eyes?

This stuff is fascinating!  Of course I mostly have no idea what you are talking about because I still think electricity runs on magic.

TT, can you recommend any good books that start with the basics of electricity and move on to more advanced electrical engineering for people like me who don't have enough tacit knowledge of the subject to really follow along in a discussion like this?

[TomC]

Hi TwoTired
     I have not looked to see but I have been told that the 500/550 alternator will fit in place of the 350/400 alternator. I have also been told that it did not seem to make any difference. The wiring needs to be modified to work.
     My problem is not with the my 400s charging as is as I live in the country. But I like to stay warm. So I would like to have an extra 35 watts to run my electric vest. For this fall getting my CB750F1 on the road and maybe fixing the motor mounts in Yamaha SRX250 seem to me to be the way to get that extra 35 watts.
     Over the winter I will give a hard look at LEDs to reduce the current used. Next spring I will get my CB550K3 engine running and compare it's alternator output with the alternator output of my CB400F1.
     In the CB400F shop manual I found a specification of 14.5 Volts X 13 Amps. Clymer's show 156 watts at 5,000 rpm.
     TwoTired thank you for your responses. Maybe we will discuss this more in the Spring.          TomC in Ohio

[TwoTired]

This stuff is fascinating!  Of course I mostly have no idea what you are talking about because I still think electricity runs on magic.

TT, can you recommend any good books that start with the basics of electricity and move on to more advanced electrical engineering for people like me who don't have enough tacit knowledge of the subject to really follow along in a discussion like this?

I think it take a naturally curious mind to be any good a electrical repair or design.  The fact that you find it fascinating, demonstrate such curiosity. (Or perhaps you are part Vulcan.  )

Most of my books are quite old.  My training booklets were Navy Issue Programmed instruction, though quite effective at teaching even dullards about electricity/electronics.
http://en.wikipedia.org/wiki/Programmed_instruction
But, I don't know where you can buy these things.  A quick Internet search found this:
http://books.google.com/books?id=KgNhk-HcI4oC&pg=PA65&lpg=PA65&dq=basic+electricity+formula&source=web&ots=tsWgEalDBc&sig=sBoG3zOBxaVYI5lEIE9CbA07fHo&hl=en&sa=X&oi=book_result&resnum=4&ct=result#PPA32,M1
It looks quite useful.  Though I can't say it is all that is needed for self study on the subject.
http://www.amazon.com/Basic-Electricity-Revised-Complete-Course/dp/0790610418
I haven't seen this one.  But the reviews give it high praise.

This looks pretty interesting!  I reviewed the chapter titles, and they cover the right topics!  First chapter starts off with good fundamentals.  Free is good!
http://www.ibiblio.org/kuphaldt/electricCircuits/

Here is something else Free that can be of aid, though it lacks rudimentary fundamentals:
http://www.hvacmechanic.com/basic_electricity_and_elecronics.htm

Hope this helps,

[TwoTired]

Hi TwoTired
     But I like to stay warm. So I would like to have an extra 35 watts to run my electric vest. For this fall getting my CB750F1 on the road and maybe fixing the motor mounts in Yamaha SRX250 seem to me to be the way to get that extra 35 watts.

Ah yes, the staying warm stimulus.  I encountered this, too.  After leather, layers, ski pants, scarves, thermal socks, etc. I still found that a 40 mile ride, pre-dawn commute in winter left me cold, what with the 70MPH wind chill.
My solution was the Vetter windjammer fairing. This made it tolerable.  Years later, I added lowers, and kicked myself for not doing it years earlier.  Legs are not only shield from ambient air, they are fed heated air off the motor, warming your legs.  And with no wind chill on chest or face, only the finger tips were at risk, and bates insulated gloves pretty much took care of that.
I know people love to sneer at the Vetter.  But it works famously in cold weather and uses NO extra power from the charging system. 
The Windjammer is a bit big for the 400, IMO.  But, the Quicksilver Version ought to be a good match for the 400.  No lowers, but it will get the wind off your chest.  You might also consider making a cold weather bike out of the 550 with a Windjammer.  The Quicksilver fairings are found with frequency.  The frame mounts to adapt to the 400, not so much.  Windjammers are often GIVEN away if you are patient and buddy up to some style mavens.

Good Luck!

[TomC]

Hi TwoTired
     There is a Vetter with mounts for a CB550 in my shed. Also some hard bags that I have had for 35 years.
     My Yamaha SRX250 has, from the factory, a Quarter or Half fairing. It does not look, to me anyway, like it would do much. But the difference between riding my CB400F1 and my Yamaha SRX250 on the interstate is huge. The wind just beats me up on the CB400F1. The Yamaha SRX250 is at that balance point were there I do not have to hold my self up with my arms or pull my self to the handle bars.
     I have been using my electric vest on the Yamaha SRX250 with no electrical power issues.
     Thinking about this I wonder how much good the vest will do on a totally unfaired motorcycle? I will see on the CB750F1.
     A quarter or half fairing is on my to do list for the CB400F1. Something like what is on the Yamaha SRX250 but shaped to follow a round headlight.
          Stay warm, TomC in Ohio

[bggann]

I find the discussion my little battery question started quite intersting - particularly to somebody with a EE degree(s).  This discussion has had a lot more basis in fact and reality that many of the electrical discussions I see.  I also run the audio/visual systems at churches and the discussion groups about audio/video are full of more myth about electricity than fact. 

This discussion has been just stock full of really good information - the rundown on power consumption was incredibly useful for my 'power plans' - and yes - I know that the Dyna 5ohms will not use less power than Honda 5ohms - now that I know the Honda's are 5 ohms (thought they were 3) - although there is the whole 'on/off' time part..  But if I'm gunna spend that power - a hotter spark seems is worth it.

Twotired - too bad so much today is "IC's" and unrepairable - this has, IMHO, stolen much of the practical learning from our younger generations.  I learned most of this stuff while building shortwave radios - from (what was the name of that company - started with an "H" I think.). My Bogan stereo had tubes - and that was great!  One of the real joys of my 400f is I can work on her - which I can't do with my car really  (Drive a chevy HHR).

There are really only a few key laws you need to know for electrics at the level of a cb400f.  One is Ohm's law - which I've seen stated here a number of times.  Ohm's law relates:

Power, voltage, current and resistance.  That covers everything on the bike but the alternator, and for that you need Maxwell's laws.

The "water" standard is think of Voltage as "pressure" as in water pressure.  Think of current (I) as flow - as in gallons per minute.
R - resistance is the resistance of water in the pipe.

Intersting history - Westinghouse (I think) and Tesla (sure) - fought AC/DC battles.  Tesla was an advocate of AC (and he was right).  Westinghouse (I think) was an advocate of DC.  One of the things Westinghouse did was point out that the Electric Chair used AC - so AC must be dangerous.

Actually, current is what is dangerous - AC/DC doesn't matter - within limits.  (At very high frequency, AC does not penetrate, but stays on the 'surface' of the conductor.  What this means is that when I was younger, me and my compatriots built a Tesla Coil - which is basically a high frequency step up transformer.  250,000 volts at some thousands of cycles per second (can't remember what the frequency was).  We coud pull 1-2 foot arcs (sparks) from the tesla coil to a wrench in your hand- and the current would flow down "your skin" to the ground.  Tended to leave burn marks in your soles - but didn't kill you).

It also destroyed all TV reception in the neighborhood.....

High Voltage was fun if you survived.

Back to Ohms law...

So - lots of pressure = Lots of voltage
Lots of flow (big pipe) = lots of current.
Little pipe = large resistance

The equations are:
V=I*R or
Or - I=V/R

The power (DC) is 
P=V*I (voltage times current). 1 amp at 12 volts = 12 watts.  At 60 Hz (household) - this works for AC too.  For AC, you use Z = Impedance, instead of R= Resistance, so for higher frequencies, Z changes.  But I digress.

You can substitute these things around
P=V*I and I=V/R - then P = V*(V/R)= V²/R. 

When you get into alternators - rotating machinery - it is MUCH more difficult.  Heck - I was having trouble following the magnetic flux discussions - and I used to teach EM theory at the college level (been a while).

Rectifiers =  bunch of 1 way valves in the pipe.  Think of the water flowing in and out of a pipe going into the bottom of a bucket.  With no 1-way valve, it does not fill the bucket.  With a one way valve - the water flows "into" the bucket, but when it flows out - the valve closes and stops it.  Sooner or later, the bucket (battery) fills.  The only limit is the pressure in the bucket (the voltage of the battery and the charging system.) If the pressure in the bucket is to higher than the pressure in the pipe - the valve does not open and the bucket (battery) does not fill (charge).

Diodes = they are the 1 way valves.   A rectifier is a bunchodiods in a certain configuration.

Direct Current (DC) = flows one way like water in the pipe.

Alternating Current (AC) = flows back and forth - would have a hard time filling the bucket with this w/o the 1-way valves.

Advantages of AC over DC = transmission loss.  We could not have the power grid today using DC because most of our power would be lost in the resistance of the wires.  With AC, you can step the voltage up and cut the current down and still deliver power

(remember P=V*I.  So 10 watts can be 1 volt at 10 amps, or 100 volts at .1 amps or 1000 volts at .01 amps.)

But - why do we have an "alternator" in the bike?  Don't need long transmission lines there and the lights and stuff are all "DC"  (remember, can't store AC in a battery).  Weight.  Alternators are lighter.  So it is lighter to put an alternator and rectifier (to convert the AC to DC) than a generator (Generators generate DC Current).

Well - I'm rambling - but I'm jazzed by all the neat learning that is going on here. 

BGann again.

[TwoTired]

Twotired - too bad so much today is "IC's" and unrepairable - this has, IMHO, stolen much of the practical learning from our younger generations.  I learned most of this stuff while building shortwave radios - from (what was the name of that company - started with an "H" I think.).

You thinking about Heathkit?

[alltherightpills]

Thanks a lot for the links TT.  I am going to print some of that stuff out so I can actually read it.

Thanks Bggann for taking the time to type that out.  I copied and pasted it into a document so that I can print it out.  It's starting to make more sense now.

Part of the reason why I wanted an old bike was so that I could learn how to do stuff and I wanted to learn how things work.  I appreciate the mechanics of a carb more than I do the computer programming of a fuel injection system.  If it's mechanical and it breaks you can probably fix it yourself.  If it is a computer and it breaks, well you are probably up a creek.  I think this has not only created a generation who doesn't know how to fix stuff, it has also created a generation of stuff that can't be fixed and is therefore thrown away only to be replaced by more things that will break and not be fixed.  Sorry for the slight hijack.  Please continue on with your electrifying discussion.  (Sorry, I couldn't resist)

[bggann]

You thinking about Heathkit?

Yeah- of course - how could I forget.  Built a number of Heathkit projects.  Then I got a car and graduated to beefing up the stereo in it.

Learned about fuses the time I shorted the 10ft line running from my battery (under the back seat) to the fancy radio.  Filled the car with really nasty smoke..

[TomC]

Hi Bggann
     "But - why do we have an "alternator" in the bike?  Don't need long transmission lines there and the lights and stuff are all "DC"  (remember, can't store AC in a battery).  Weight.  Alternators are lighter.  So it is lighter to put an alternator and rectifier (to convert the AC to DC) than a generator (Generators generate DC Current)."
     Generators do not generate DC current. They generate AC current and use a mechanical rectifier. The commutator in a DC generator converts AC to DC by connecting coils as the current is flowing in the same direction. Commutators leave some thing to be desired. At high speed they fly apart. At any speed they seen to be what limits the amount of current that a generator can output. This is one of those design problems. Put more copper in the segments of the commutator to conduct more current. More copper means more weight so more likely to fly apart as it gets spun faster. Look at the commutator of a generator then look at a slip ring on an alternator. Which is easer and cheaper to make? My guess is cost of manufacture is the real reason for the switch from generators to alternators.
          TomC in Ohio

[TwoTired]

DC generators have a commutator and brushes.  These wear and produce dust as the commutator sections saw into the brushes. A closed system means that dust is retained to interfere with operation.   Also, pulling 10-20 amps out of a commutator requires substantial surface area, meaning a large commutator, brush, brush holder, etc.  Further, DC Generators have the large currents developed in the armature, these bulky windings are subjected to ever greater inertial forces as the RPMs increase. The winding insulation is highly stressed under these conditions.  Finally, there is the inertial mass's resistance to speed change that slowe engine rev up response in small displacement engines.
At high RPM, drawing current through the fast moving commutator/brush interface becomes more difficult.  Usually requiring multiple brushes and a bigger commutator segment section on a larger diameter commutator.  But, this is a trade off, as larger commutator diameters are subject to higher centrifugal forces.  Commutator segments are bound together with an insulative resin, whose adhesive qualities are taxed under the effects of brush contact heating and centrifugal forces trying to remove the commutator segments from the armature.  You could design a speed reduction device so the armature spins slower than the crankshaft.  But, that adds complexity, bulk, and weight, too.
A 10,000 RPM,  150 Watt DC generator, I would expect to weigh twice what the alternator in the SOHC4 does, and have a far shorter maintenance free life.

Even slip rings in Alternators incur brush repair intervals.  But, only the small weight/wire size field coil is powered with relatively low currents (~2 amps) and has a fairly small rotating mass.  Even so, these rotors imply centrifugal stress on the windings, the winding wire insulation breaks down, causing field coil shorts and operational failure.

The early SOHC4 alternator, has all the major output current flowing through a fixed position Stator.  The field coil is also stationary.  Only the rotor pole pieces rotate which are simply, formed lumps of metal.  It is essentially maintenance free.
Which, many might determine is a fair trade off for a non-linear output characteristic.

That's just my unsolicited thumbnail analysis...

Cheers,

[bggann]

    Generators do not generate DC current. They generate AC current and use a mechanical rectifier. The commutator in a DC generator converts AC to DC by connecting coils as the current is flowing in the same direction. Commutators leave some thing to be desired. At high speed they fly apart. At any speed they seen to be what limits the amount of current that a generator can output. This is one of those design problems. Put more copper in the segments of the commutator to conduct more current. More copper means more weight so more likely to fly apart as it gets spun faster. Look at the commutator of a generator then look at a slip ring on an alternator. Which is easier and cheaper to make? My guess is cost of manufacture is the real reason for the switch from generators to alternators.
          TomC in Ohio

TomC is of course correct, a "DC Generator" is really an AC generator with a mechanical rectifier.  I was taking a more macro view as I didn't want to dive into the details of what is inside.  In other words, a "DC Generator" must have the commutator inside it - it is part of the function.  So what you get on the output terminals is rectified (albeit, not all that cleanly) DC current.  In an alternator, the rectifier is a separate part - sometimes mounted on/in the alternator (most automobile alternators these days have the rectifier built in, or at least "mounted" in it - as is the VR).  In many older applications, the rectifier is bolted on somewhere external.

The other distinction is that an alternator can work just fine without a rectifier -but it creates alternating current.  The DC generator, because the 'rectifier' is part of it, will not.

As for speed - at the higher reaches of 10K and so, brushes and such are a problem and they do require maintenance.  All part of the reason that alternators (and AC induction motors) became popular.

Today - virtually all power (except solar cells and some wind turbines) is generated by alternators.  They typically rotate at 1800 or 3600 RPM (unless you are in a part of the world that runs at 50Hz, then the rotational speed will be different). 

BTW - I was wrong about the Tesla/Westinghouse battle.  Westinghouse was on Tesla's side in the AC/DC battle, it was Thomas Edison who promoted DC.

There are some real advantages to DC.  You can store it in batteries.  You can parallel DC generators easily (you must precisely match the frequency and phase of AC generators, or they will smoke each other - and I mean _precisely_.  It is really pretty amazing that the AC power grid works at all given how carefully the frequency and phases need to be matched.)

Anyway - yes - a DC generator is an AC generator with a 'mechanical' rectifier.

As for why Alternators in cars now (the transition happened in the 60/70's).  Cost, size - they are really different expressions of the same thing. 

Of course, all of this is realtively mute as the bikes all have alternators....

[Spikeybike]

I wonder how many readers out there have glazed eyes?

this thread reminds me how much i really don't know

[TomC]

Hi Baggann
     "The other distinction is that an alternator can work just fine without a rectifier -but it creates alternating current."
     I have a Bultaco that runs the lights and horn on AC. No battery of course.
          TomC in Ohio
PS Baggann looks like you were about 1 1/2 years old when Chrysler Corp. introduced alternators across the board.

[bggann]

Hi Baggann
     "The other distinction is that an alternator can work just fine without a rectifier -but it creates alternating current."
     I have a Bultaco that runs the lights and horn on AC. No battery of course.
          TomC in Ohio
PS Baggann looks like you were about 1 1/2 years old when Chrysler Corp. introduced alternators across the board.

Cool - what runs the ignition?  Is there a rectifier - or does it use a magneto (or is it diesel )
I wasn't working as a mechanic yet at 1 1/2... - never really did much work on Chryslers anyway.  Were they as peicemeal then as they were later (meaning - they changed the parts on a whim..)

(Never been called bag-gann before.... new nickname! )

[TwoTired]

I wonder how many readers out there have glazed eyes?

this thread reminds me how much i really don't know

If you're smart, that's something you'll realize throughout your life.
IMHO

[Spikeybike]

If you're smart, that's something you'll realize throughout your life.
IMHO

well put , my friend