Topic: New Dyna S and now voltage issue

[IndyFour]

1974 CB550K - stock coils/wires/caps

Well, I knew it was too good to be true.    

I installed a Dyna S ignition on my bike after fiddling with points for the past year not being able to get the bike timed up well (cheap replacement points/plate/etc.).  The Dyna makes the bike start and run like a top and the timing is spot on now.

Went for a 125 mile ride this morning and upon return home, I parked and went over to open the garage door.  Back to bike to fire it up and pull in.  Not enough voltage to turn the starter.  The battery is less than a year old and always put on a tender when parked.  I've never had any charging issues before today.  The Dyna is the only thing that has changed since my last ride.  It kicked over o.k. and started, but not by electric start.

I did a quick test to see if the bike was charging and it appears to be according to my quick test with the multimeter.  My trip this morning was almost all highway, so the bike should have been charging most of the time and keeping up.  My test showed a voltage of about 8.5 volts when idling (after several start attempts and lights on)....as I rev, it climbed up to about 10.5v and leveled....back to idle and it would drop again slowly.  Got down to 7ish volts at one point.

What about this Dyna ignition is sucking so much power?  Does it inherently draw lots of juice as it works?  Maybe I got a bad one.  Does the stronger spark that this contraption supposedly produces cause more draw?  Maybe my charging system has met its limit now with the Dyna installed?

Did a search here on the forum and just found a few bits here and there, but nothing that seemed to fit this scenario.

Thanks for your advice.  Maybe I'll be going back to points (decent ones) now?

[Gordon]

Charge the battery fully and then re-do the charging system test.  The Dyna-S does use a little more power, but it's nothing a good condition 550 charging system shouldn't be able to handle.  Are there any other changes to the bike that would draw more current?  H4 headlight?  3ohm coils? 

[IndyFour]

The coils are stock.  The bike is plugged in currently and is charging.  I'm hoping it's a fluke or a one-time thing.  We'll see.  I did add an l.e.d. license plate frame a while back, but it draws very little.  Headlight is an old Stanley sealed beam.  The only other electrical modifications that I've done are the addition of a headlight relay and a relay to power the coils. 

I'm thinking what's happened is that I had already maxed out on my net power gain from the charging system and with the addition of this Dyna I may have gone over the top, resulting in a very slow net loss.  I'm hoping that's not the case, though.  If so, maybe I can tip the balance back by replacing a few bulbs with l.e.d.'s.

I'll do as you suggest and test once charged up.  Thanks.

[Stev-o]

I added Dyna to my 550 a couple of months ago too. A few weeks ago, I went for a short ride, bike ran fine and once home, turned the motor off in the driveway. 2 min later, tried the electric start and no go, but kicked right up.
Charged the battery overnight and has been fine since.

Hope same happens to you.

[IndyFour]

That's good to know.  My fingers are crossed.   Thanks.

[Bodi]

The Dyna S does take more ignition power than points. The system powers the points all the time except for a short period at and just after the spark is produced. Points have a constant dwell angel, meaning the points are open some percentage of a crankshaft rotation - usually about 25%. The power for the Dyna electronics is negligible but also additional. This extra power load from the extended "coil-on" time is sometimes enough to overtax a charging system especially if it isn't at 100%. Cleaning all the harness connectors often improves alternator output enough to overcome this if the bike's rated output should be sufficient. Going to a LED tail-light bulb and disconnecting the front marker bulbs is the next step. I'm not sure of the power supply vs load balance for a 550. On a 350 or 400 the alternator not quite enough with a Dyna and stock lighting - the battery will go low on city rides and it can not recharge a low battery, but will maintain charge on highway rides if it's working at 100% efficiency.
Your relay coils take a bit of juice and the headlight and ignition coils will draw more power since their supply voltage will be higher.

[TwoTired]

Points are set up for dwell of 195 degrees of crank rotation. 195/360 = .54 or 54% coil on time.
The Dyna-S dwell time is 315 degrees of crank rotation (using Hondaman's ignition analysis). 315/360 = 0.876 or 88% coil on time.

There are 2 coils driven by the battery.
All Stock: 31.25 x 2 = 62.5W x .54 = 33.75 Watts average consumption.
Stock coils w/ Dyna S:   62.5W x .88 = 55 Watts average consumption.

All the above assumes a purely resistive load which the coils are not.  Still, it should be obvious that the Dyna S will place a higher load on the bike's system than the standard points.

The employment of the relays for headlight and coils wreaks of a band aid solution to the bike's wiring, connectors, or switch issues/degrading.

If those elements of the bike are losing battery voltage, then the voltage regulator and alternator aren't getting full power from the battery, which makes the alternator output weak, even in full power output mode.

When you get the bike running again, measure the voltage at the Vreg input.  Or, measure the voltage drop between battery and vreg.
Do have all the system loads on during the test.

[IndyFour]

Thanks again guys for the explanation and the assistance.

The bike charged up over night and I went out just now to get it going and do some testing.

Using the chart in the Honda service manual, I checked the battery voltage at the various RPM ranges and with the headlight OFF, they were pretty much fine if only just a tad low.  With headlight on, though, it would hover just under 13v if I maintained above 4000 RPM.  Anything less than that yielded a very slow loss of voltage.

TwoTired:  I measured the voltage difference of the battery versus the input of the voltage regulator.  Looking through the shop manual, I couldn't really determine which terminal was the input.  I can see the three terminals back in there and can reach them with the tester, but they do not seem to match with what the shop manual says and I cannot see what color the wires are.  Looking at the bike from the side, the top-most terminal gave no reading regardless of condition....so I assume it is ground (the manual shows the middle terminal is ground  ).  I tested the bottom-most terminal and it consistently gave me a reading that was about .5v less than what the battery reads (regardless of whether the bike is running at high idle or not running with just the key turned on).  Same goes for the middle terminal.....about .5v below reading of the battery itself.

My eyes are going crossed trying to read this diagram  .  Can I assume that the main key switch could possibly be at fault for this voltage drop at this location?  It so happens that I have a new (still in the box) replacement switch that came with the bike when I bought it (hmmmmmm  ).  I may go ahead and just put it on there and see what happens.  They key has been a little tricky (the rollers, that is) lately, so it wouldn't hurt functionality-wise.

Thanks again for the help!

[Deltarider]

Sometimes turning the keyswitch very quickly, say twenty times can clean the contacts. Best done with the ignition switch turned off.

[TwoTired]

The voltage drop through resistive connections is proportional to the current being carried through those connections.
If the load is 10 amps through the connection, a .5V drop indicates a 0.05 Ω resistive connection.
If the load is 1 amp through the connection, a .5V drop indicates a 0.5 Ω resistive connection (which is pretty dismal).
ohm's law is E = IxR
Given your statement that both the coils and the headlight no longer draw power through the key switch.  I would think that your reading indicates an issue with the switch contacts or connections between the Vreg and Batt POS terminal.
I should add that resistive connections convert power to heat.  That power is lost and, in effect, stolen from the output capacity of the charging system since it is directed away from both battery and system loads.

If you have the stock regulator, the terminals are often stamped with their function.
IG - is the black wire or power input to the Vreg.
E - is the earth ground connection to the frame or Battery NEG terminal, (Green wire Honda color).
F - is the Field connection to the alternator (White by Honda standard).

A voltmeter display a difference in potential between its probes.
You can measure the Vdrop across any resistive element by placing the the probes on either side of the element while it is passing current through it.
For example, you can place one probe on the battery POS terminal and the other on Black wire to the Vreg.  The meter will display the voltage lost between those two points due to resistive losses between them.  If you also know the current being carried through the circuit, you can calculate the actual resistance between the probes.
You can measure each element in the path for resistive Vdrop, the sum of all of them will equal the total Vdrop.

Cheers,

[IndyFour]

Thanks TwoTired.  That info is very helpful.

I went out and disconnected the old switch, cleaned the connector, and installed the new switch.  No change.  So, it must be between the battery and the voltage regulator.  I'm going to go pull it off the bike and inspect the connections.  It is the original one from what I can tell, so maybe something is corroded back behind it somewhere.

Thanks again for the info.  Will report my findings.

[IndyFour]

Last update for the evening.  I spent a couple of hours chasing wires and connections.  It appears that it is not just one connector or wire, but rather the sum of several very minor drops here and there that are adding up at the end.  I get a loss of .1v here and .1v there etc.....by the time the fused red wire goes through the harness, through the key switch, back through the black switched power lead and to the connectors back under the side cover, I am down about .5v.  I've cleaned all of the connectors that I can trace and no real improvement so far.  I will go through it all again tomorrow evening in case I missed something.  I hope it is not a faulty wire somewhere in the harness.

[IndyFour]

Final update. 

After much digging around, I determined that the voltage loss was mainly the black wire going from the key switch to the voltage regulator/winker relay/etc.  I wasn't about to tear the harness apart, so my solution was to solder in a patch or jumper black wire that runs from the new key switch to the voltage regulator connection to provide an uninhibited path for the current to pass.  After doing that, I now have about .4v more power at the voltage regulator and winker relay.

In addition, I ordered a full set of L.E.D. bulbs for the tail light, front marker/signals, rear signals, and the four gauge back lights.  Hopefully by doing all this I will come out ahead and not lose juice while riding.

I think my next step will be some more testing of the charging system and see if an adjustment of the voltage regulator is in order.

Thanks again for all the assistance.   

[Bodi]

Your measurement at the regulator showing the same voltage at two terminals suggests the regulator is OK. One of those terminals is the +12V ignition power on the black wire, the other is the power out to the alternator field coil. The regulator won't start shuuting off the field coil until the input voltage reaches about 14V where the battery is reaching full charge. The adjustment just changes this voltage, is not particularly easy to do right, and can result in a boiled dry battery if it's set too high (and your alternator has enough output to get there).
Note that the field coil magnetic field makes the alternator produce power. Any resistance in the coil circuit will rob you of power, it's worth checking all the connections in the alternator wiring! Usually there's the engine connector plus a set of bullets somewhere under the alternator side engine cover, and the bullets are particularly prone to corrosion since they get heated up to engine temperature and cooled down again every time you ride. The three yellow wires need to have good clean connections too.
Few affordable meters read low resistance - below 5 ohms or so - very accurately. If you touch the probes together and adjust an analog meter to zero then you should get a fairly good reading. With a digital meter you can subtract whatever it reads with the probes touching from the measurement value and get a decent guess at the actual measured resistance. For accurate measurement you need a specialized meter or a Wheatstone bridge, but we really don't need that accuracy.

[IndyFour]

Your measurement at the regulator showing the same voltage at two terminals suggests the regulator is OK. One of those terminals is the +12V ignition power on the black wire, the other is the power out to the alternator field coil. The regulator won't start shuuting off the field coil until the input voltage reaches about 14V where the battery is reaching full charge. The adjustment just changes this voltage, is not particularly easy to do right, and can result in a boiled dry battery if it's set too high (and your alternator has enough output to get there).
Note that the field coil magnetic field makes the alternator produce power. Any resistance in the coil circuit will rob you of power, it's worth checking all the connections in the alternator wiring! Usually there's the engine connector plus a set of bullets somewhere under the alternator side engine cover, and the bullets are particularly prone to corrosion since they get heated up to engine temperature and cooled down again every time you ride. The three yellow wires need to have good clean connections too.
Few affordable meters read low resistance - below 5 ohms or so - very accurately. If you touch the probes together and adjust an analog meter to zero then you should get a fairly good reading. With a digital meter you can subtract whatever it reads with the probes touching from the measurement value and get a decent guess at the actual measured resistance. For accurate measurement you need a specialized meter or a Wheatstone bridge, but we really don't need that accuracy.

Thanks for the explanation.  I will do as you suggest and check those connections.