Topic: NewAlternator? Charging system fun. CB550 - fixed!

[Hito550E]

Quick question before I buy anything.

'74 CB550
the battery discharges and bike dies after a while. 

Here's where I have checked so far. Per the service manual instruction I hooked up the voltmeter and ammeter.  voltage never comes up to 14 free reving in idle no matter how high I go.  Current is coming out of the battery at any speed.

I just replaced the regulator and rectifier with new solid state units from http://www.oregonmotorcycleparts.com
Still no charging.

Measuring the white wire that comes from the regulator to the powered alternator coil, it is a 0 volts with the key on engine off as well as key on engine running.  Hooking up the ammeter in line seems to indicate that there is no current flowing. 

If I disconnect the white wire at the regulator, I got battery voltage on the regulator side once, but couldn't repeat it.

The resistance of the alternator power coil is 5.5ohms.  The manual states it should be 4.5-5ohms.  It does not seem shorted to ground. 

Does anyone have any other good ideas?  I find it hard to believe that it is the brand new regulator I got.  I have a factory one as well i need to try.

some questions.

1.  Should there be current going through the alternator coil when the bike is idling?  If the regulator is sending power to the alternator coil, should there be voltage between the green and while wires going to the alternator?  v=IR?  There should be 12.5v/5.5ohms = ~2.3amps?? passing through the alternator coil? if the battery is at 12.5v.  If there is no current does that mean the regulator is not working?


FIXED UPDATE!: Well I figured out the issue.  The oregonmotorcycleparts.com regulator I had installed was not isolated from the frame.  First I noticed that the stock regulator was isolated from the frame with nice rubber grommets.  So I tried leaving the regulator unbolted from the bike and hanging such that the body would not be grounded to the bike, and just like that the bike charges.  No power on the white wire to the alternator when the recifier is directly connected to the mounting bracket.

I

[mattdaniels]

Do you mind me asking where you purchased the alternator? I am having the same prob on my cb400f.

[Shenanigans]

If I understand correctly your getting NO power on the white wire which gives power to the alternator. The way the alternator works is that it need a little bit of power in to produce any power out. So your problem could possibly not be the alternator itself but something "before" it. Do you have power into the regulator/rectifier?

You probably don't want to hear this but I bought a brand new solid state unit and could not get it to work. No matter what I did, it may be possible that I fried it somehow I guess. I said screw it and ordered another one and it worked fine.

[Honda_Nut]

These machines use an electromagnet to generate electricity as opposed to a permanent magnet found in magnetos. Anyway, if you don't have a little juice making a magnetic field in the stator, you get no charge.

[TwoTired]

'74 CB550
the battery discharges and bike dies after a while. 

some questions.

1.  Should there be current going through the alternator coil when the bike is idling? 

Almost certainly, unless the Vreg thinks the battery is higher than 14.5V

If the regulator is sending power to the alternator coil, should there be voltage between the green and while wires going to the alternator? 

Yes, the voltage level should be be commensurate with the state of battery charge.  High battery voltage, low white wire voltage.  Low battery voltage, High white wire voltage.  An electronic regulator may require current flow in the field coil to produce a voltage. So, open circuits can effect test results.

v=IR?  There should be 12.5v/5.5ohms = ~2.3amps?? passing through the alternator coil? if the battery is at 12.5v.

The 550 Field coil should be 4.9 ohms +/- 10%, and draw a nominal 2.55 Amps when provided 12.5V.
Check your lead resistance or connector corrosion.

If there is no current does that mean the regulator is not working?

Pretty much. The field coil is the driving force for the the electromagnet.  Alternator needs a magnetic field to produce power.

For testing you can jump from battery POS to the white wire (disconnected from an electronic regulator). The alternator should then charge the battery when the engine is revved up.  Without the regulator, there is some risk of battery overcharge.  So, don't let it get above 14.5-15V for very long.

Cheers,

[Hito550E]

FIXED!

If anyone has a regulator from oregonmotorcycleparts.com  make sure you isolate it from the bracket or it will not work

[technojock]

FIXED!

If anyone has a regulator from oregonmotorcycleparts.com  make sure you isolate it from the bracket or it will not work

I don't think so.  There has to be something else wrong since I have hundreds of these in service and this is the first time I've heard this.  Have you gone through the troubleshooting steps in article #19 on my FAQ page?
http://www.OregonMotorcycleParts.com/FAQ.html

If you do all this and the regulator still only works insulated, then there is something wrong with this particular unit and I would warranty it.  I have the best warranty in the biz and all I ask is that you do all the troubleshooting before you blame the part. 

Tony