Honda-SOHC
SOHC.co.uk Forums => The Black Bomber Board => Topic started by: royhall on May 18, 2021, 02:30:21 PM
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The Black Bomber is running okay in every respect except that it isn't charging. Voltage across the battery stays the same with engine running or not. With the multimeter 10A in series with the battery positive it's showing a negative reading ie. no charging. I disconnected the output from the rectifier and it measure just 2V when the engine revs. Disconnected the regulator and tried again, exactly the same. Can I check the output from the alternator at the harness where it connects to the rectifier as getting to the connections for the alternator itself is almost impossible. If I disconnect rectifier and regulator what reading should I be looking for with the engine running, AC I assume. I'm way out of my comfort zone with this so any help would be appreciated.
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20-60volts ac between any pair of alternator wires is average
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Thanks Bryan. Is that multimeter between each cable in turn and the battery negative.
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I shall watch this with interest, my CL450 is on its original voltage regulator and rectifier, and I have never seen more than 12V across the battery terminals.
That said Ive not had the lights go yellow, or any sort of misfire caused by low voltage, but recently after a lot of short trips I found the battery was too low to work the starter. That's when I found out that it will start fist kick, something I'd never tried before - I have officially retired from kickstarting, and won't buy a bike without a a starter motor). I gave it a go on the Optimate, its been fine since.
I believe there is an extra coil in the alternator, that is only used when the lights are on, so there may be that to consider.
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No mate as i said between PAIRS of yellow generator wires
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No mate as i said between PAIRS of yellow generator wires
That's for a 3-phase alternator Bryan with three yellow wires. The Bomber is single phase.
A common trick is to permanently switch on the night charging coil. (IIRC Yellow and white wires commoned)
Not sure on the AC voltages out of the Bomber alternator Roy but I will check.
Off the top of my head I would think typically around 20 AC volts at idle over 50 volts at 5k rpm (night coil switch in) unloaded (i.e. Coils open circuit.
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Still has to be two ends to each winding
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I think this is my weekends challenge as it's going to be raining anyway. As I say, I am way out of my comfort zone with this so any guidance you guys can give would be greatly appreciated.
Ash, I don't know how they are different but I'm using a later stator 1968 onwards and also a later rotor. I believe it's actually from a K3, does that make any difference. I think I may have to get to the stator cable ends to carry out these tests. It's in a very tight space between the rear engine mounts and requires the removal of the mounts and the clutch actuator cover, but probably the best way forward or I cannot test the alternator without going through the harness and that's not eliminating the downstream wiring.
It's about time I got to grips with electrics as I have been muddling through for years and getting away with it. I am quite competent at following a wiring diagram, it's when it comes to this sort of thing that I lack knowledge of how things actually work and the correct use of the multimeter. Come September I may enrol myself at the local college's vehicle department for a crash course on auto electrics.
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Further to the above, I just found this online. Now I am bloody confused. https://www.hondatwins.net/threads/nos-cb450-k1-alternator-resistance-measurements.7331/ (https://www.hondatwins.net/threads/nos-cb450-k1-alternator-resistance-measurements.7331/) This will probably make a lot of sense to you Ash and may even be useful when you get to building yours. After reading it I'm thinking I may have the stator wires connected incorrectly as I'm more used to the fours where there's three yellow output wires.
Just a thought, are these alternator stators repairable?
There's also a good thread about it here. https://www.hondatwins.net/threads/cb450-charging-problems.78881/ (https://www.hondatwins.net/threads/cb450-charging-problems.78881/)
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From Jensen's diagram and other post I made this up attached . VAC is the test multimeter switched to volts AC range.
I would think with a newer model epoxy coated stator and the later rotor you would be fine Roy and that's what I am going to use on mine.
Also if you are using a later model voltage regulator ('crow-bar' clamp .. same function as Zener diode on 60's Triumphs but much better) temporarily disconnect it just in case it is faulty. Of course the K0 never had one ..it relied solely on a good battery to regulate the voltage.
[attachimg=1]
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Cheers Ash that looks simpler. Not sure yet but I think I may have them connected wrongly. I am used to the three yellow wires that can be connected any which way. What's the actual difference between a single and a three phase unit.
I will no doubt have a million more questions to ask.
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Totally different Roy .. the early 3-phase charge system is really well explained in this Bulletin in the link below.
https://www.dropbox.com/s/2oqrx5cvv7byqao/3-phase%20Honda%20Charging.pdf?dl=0
Basically the single phase one is a permanent magnet spinning inside a set of coils which produces a single-phase AC output. This is then full wave rectified by the rectifier and thus converted to DC which then charges the battery. There are several coils but they are connected in both series and parallel combination (see Jensen's diagram) to give additional output (giving more power when the lights are switched on) ... but you can basically treat it as one coil.
Feel free to call me if you get stuck. :)
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I think from memory I had trouble distinguishing the cable colours on the stator as they were very faded. So this may be fun and games.
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Every single post I can find on this has the same problem. You wonder how many 450s are out there actually putting out a decent charge, and how good at it were they when new?
I've seen it suggested that 50 year old rotors can lose their magnetism, I was surprised to find new ones actually on sale at CMS. However sod Eu706.00 plus P&P etc for a game of soldiers.
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Not sure if the spanner test is good enough but it takes a firm pull to detach it from the magnet. Just thought, the rotor in at the moment is a NOS item, still 50 years old though.
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This is the wiring diagram I modified at the time. Does it look correct? It has added, a voltage regulator from a later model, and a Silicone rectifier in place of the Selenium unit.
[attachimg=1]
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That's weird Roy only one coil and contact breaker?
This is a decent 5-speed diagram .... of course in the Bomber loom the brown wire changed to pink and the pink changed to white
Basically on the 5-sp later codes the Yellow and pink outputs are wired directly to the single phase silicon rectifier. The white wire is the night charging coil and goes through the headlamp switch and connects to the rectifier when the lights are switched on to boost the power (the switch connects together the white and yellow wires with light on) . The yellow wire also connects the the solid state regulator as a sense wire. The other two wires of the regulator connect to the battery positive (black via ignition switch) and negative (green) .. as drawn in your diagram.
[attachimg=1]
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Thanks for that Ash. I have seen that wiring diagram before, unfortunately it does not represent the wiring that's actually on an early Bomber. As a for instance the lights are controlled by the ignition switch and not seperate switches, plus the pink from the generator does not go straight to the rectifier but via the ignition switch to cut in with the lights. Although my diagram only shows the one coil (I didn't bother changing that bit as it's obvious) it is actually what was on my bike originally except for the minor voltage regulator and rectifier changes. I will at some point change it to show two coils and points then it should be correct. Do the regulator/rectifier changes I made look correct to you.
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Thanks for that Ash. I have seen that wiring diagram before, unfortunately it does not represent the wiring that's actually on an early Bomber. As a for instance the lights are controlled by the ignition switch and not seperate switches, plus the pink from the generator does not go straight to the rectifier but via the ignition switch to cut in with the lights. Although my diagram only shows the one coil (I didn't bother changing that bit as it's obvious) it is actually what was on my bike originally except for the minor voltage regulator and rectifier changes. I will at some point change it to show two coils and points then it should be correct. Do the regulator/rectifier changes I made look correct to you.
No because the PINK on the late alternator should connect directly to the rectifier AC input ..this was the BROWN wire originally on the K0 so it should connect to the BROWN loom wire (not via the switch). The YELLOW wire is the same for both models and that should connect directly to the other AC terminal of the rectifier (it also goes to the switch and to the regulator you added) . The WHITE wire of the the late alternator was PINK on the K0 so the WHITE wire of the late alternator should connect to the K0 loom PINK wire. Hope this all makes sense :)
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That makes sense Ash. This is the headache for this weekend. There's a possible extra mix up as the harness is also new so could be either wire colours will have to recheck. It's a really good quality harness that came from Vietnam, not too expensive either. Is there another way to check which wires are which from the alternator as the colours are very faded and hard to really be sure about. The pink has faded virtually white and the white is stained darker, I think? Once I get this all right I will update my wiring diagram to correctly show what is actually there.
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If you look at the coil diagram posted earlier one pair of wires has just two coils and the other pair four coils(when link disconnected) now assuming all the coils are the same the resistance will be different, in theory i would hope themanual had numbers BUT you need a good meter as the readings will be low
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If you look at the coil diagram posted earlier one pair of wires has just two coils and the other pair four coils(when link disconnected) now assuming all the coils are the same the resistance will be different, in theory i would hope the manual had numbers BUT you need a good meter as the readings will be low
The daytime/night-time coils are wound from different diameter wires I believe Bryan. I will check what the resistances should be later as at work today.
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Working on the fly here Ash as ive never done a 450 and very few 500twin
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I have been back in the garage and had a look at the wiring. Due to brown becoming pink I had two wires reversed, but surely there would have still been a detectable voltage to the battery. Whilst it was apart I got the following readings:
Resistance
Pink to Yellow is 1.9 ohms
Pink to White is 1.4 ohms
White to Yellow is 2.2 ohms
Running voltage
Pink to Yellow is 21 volts idle and 49 volts revved (open circuit)
Battery voltage
12.69 volts engine off and 12.73 volts with engine revving
Amperage
Measured between battery live and live lead
1.5 amps with engine revved (lights off)
4.1 amps with engine revved (lights on)
Do any of the above figures look correct. I was expecting more amps with the lights off looks fairly poor. Does this mean the battery is now charging since I have swapped the two cables?
Also, I don't know if this is correct but I disconnected the red output from the rectifier and measured the voltage between that and battery negative and it was 27 volts (not sure I did that correctly so it may be meaningless).
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Is that +ve amps? If so its fine. Due to the way the charging system works you wont get high numbers
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That's right Bryan positive amps. Do you think that's good enough. I was surprised at the extra boost with the lights on due to the other coils cutting in. Perhaps I should always run with the lights on.
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That sounds a lot better Roy
This graph shows the currents/voltages for the 5-speed alternator without and with the voltage regulator connected.
[attachimg=1]
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Are you using standard or led bulbs?
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Standard bulbs.
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Must just be a characteristic of the charging coils, it looks similar to the old Lucas system where there were 3 charge levels,
1 two coils charging with the other 4 shorted, this caused the coils to reduce the effective magnetic field of the rotor
2 two coils charging with other 4 open circuit, increased mag field slightly improved charging
3 all 6 coils charging full output depending on revs
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Looking at your figures again and comparing them to the 5-speed Honda graphs Roy, I think you now have a really nice charging system with the added bonus of the solid state regulator to stop you 'boiling the battery' or blowing bubs if the battery isn't perfect.
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That's good to hear, I was thinking it looked a bit low compared to the graph. I'm not sure the output is so great to ever activate the regulator but knowing it's there gives peace of mind.
I shall now get it run in and see how the charging goes. The good thing is I have learned a whole lot about electrics whilst doing this. Thanks guys for all the advice along the way.
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One feature of that regulator is that if you have a poor battery connection or a failing battery, it prevents the high voltage from the alternator popping every bulb on the bike. It's a very neat little circuit for 1968 when it 1st appeared, in terms of solid-state electronics (it uses a power thyristor to clamp the excess voltage).
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I found this from a CB77/450 Service Bulletin attached Roy .. From 1968
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I found this from a CB350/CB450 Service Bulletin attached Roy .. From 1968
(Attachment Link)
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Thanks Ash. I would appear to be back to front, ie much higher amperage with the lights on. I would have thought it would be the other way around.
I think I may just ride it with the lights on all the time, I get at least a 4 amp charge that way.
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Thanks Ash. I would appear to be back to front, ie much higher amperage with the lights on. I would have thought it would be the other way around.
I think I may just ride it with the lights on all the time, I get at least a 4 amp charge that way.
Yes it is confusing ... but as long as you have a decent positive charge once the engine is running at all engine speeds you should be OK. It's really the ability of the charging system to replenish the battery charge lost, after cranking the engine with the electric start /ignition coil current, which is critical (provided that the running charge is positive).
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It's a bit rough and ready (I will try and improve it when I have time) but this is now the wiring diagram that reflects what is actually on my 1967 Black Bomber. Fitted is a new harness with original Bomber wire colours, an alternator and rotor from a later K4 model, a voltage regulator from a later model and an AGM battery. It is all fitted and working correctly. Hope this is a help to anyone that has been watching this thread.
[attachimg=1]