Black Bomber not charging

[royhall]

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.

[Bryanj]

20-60volts ac between any pair of alternator wires is average

[royhall]

Thanks Bryan. Is that multimeter between each cable in turn and the battery negative.

[MrDavo]

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.

[Bryanj]

No mate as i said between PAIRS of yellow generator wires

[AshimotoK0]

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.

[Bryanj]

Still has to be two ends to each winding

[royhall]

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.

[royhall]

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/   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/

[AshimotoK0]

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.

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[royhall]

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.

[AshimotoK0]

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. 

[royhall]

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.

[MrDavo]

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.

[royhall]

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.