This pertains to a Yamaha TDM 850, but is pretty basic. It is just that I can't tell the difference from an amp and a volt. The bike wouldn't start due to a low battery. Jumped it to start but after riding, the battery was not being recharged. It spent the night on a 1 amp trickle charger and started the next day after the charger was removed about 3 hours. My cheap chinese made voltmeter said the battery had about 12.4 volts. Discharged but not dead. When I started the bike the voltmeter was bouncing all over. Mostly between 12-12.4 volts with an occasional spike to 13.5volt. What is the verdict, rectifier/regulator or stator? Since the stator is a $500 item is there a way to test to narrow it down? If the verdict is stator, can they be rebuilt?.
<BR> Take a reading with the voltmeter set to AC volts, and post back. And, list a few motor RPM levels. Say idle, 2000, and 4000. Go ahead and retake the DC volts too. Twist the idle down a notch or two, and see what happens to the AC and DC output. Too, if the stator is easily accessible, maybe take a look at it. - Jim<BR><BR>
<BR> Yea that's right Merc. The alternator is a 3-phase AC device. Oh yea, HEY TDM, can you set up the motor so it can be cranked by the starter but not actually start? Maybe pull the coil primary? Or both plug wires? Or will it crank with the killswitch switch off? Anyway, monitor the DC volts while cranking the motor for 5 seconds. - Jim<BR><BR>
The voltage at the Stator is AC. At the rectifier it becomes DC and then charges your battery. Class Dismissed.
<BR> That is a practical truth. And is practically true if the rectifier is working properly. An aside; The rectified 3-phase AC will always have it's original AC signature. After rectification the sign becomes absolute (in this case, positive, or +), and the frequency doubles. Though the original three phases can be derived from the DC-offset AC signal. If you take a 4-channel scope and look at the 3 phases and the 1 rectified output, and 'overlay' the 4 signals on the screen like a transparency, the rectified output 'trace' will fit atop the 3 phase traces. - Jim<BR><BR>
Why not just ohm the stator coils, and check the diodes(forward and reverse bias) of the the reg/rec. And when you jumped it did you do so with a running car? That can fry your reg/rec. It's DC after the rectifier if it is working, pulsating DC.
I do appreciate the help, but I got to admit that one lost me. Right now, at the battery leads i am getting 12.2 volts. Start her up and I am getting less than 12v. Following the instructions for what I think is AC output I am getting readings bouncing all over then a steady 024 depending on the RPMS. (AC is the 750v position on the tester, right) the problem is I don't understand the device instructions symbols. everything on a TDM is buried under the plastic and fuel tank. All have to be removed to get to the battery The manual for the bike goes through a list of eleminations to solve a non charging problem. To test the stator they say to check the current measured in ohms between the 3 white wires at a plug connection. The diagrams do not make clear which is #1 wire that the positive tester lead goes on and which is #2&3 for the negative. That connecter is burried next to the battery. I can reach the Regulator plug, but again do not know which white wire is which. According to the manual if everything else checks than it is the rectifier/regulator.
<BR> The term 'alternating', as in alternating current, does not demand a change in direction or sign (+ or -). A variation in voltage is also an 'alternating' current. What we commonly refer to as a DC square wave say, is also an AC waveform. It's an AC waveform with a DC offset. In the case of an alternator and rectifier output, it is a small AC signal with a 13.8 volt positive DC offset. That AC signal is what TDM is trying to measure. - Jim<BR><BR>
I understand that (I did electronics many many moons ago) but the rectifer then converts the AC to DC to charge the battery - you can't use AC to charge a battery (IIRC). That is why I asked.
Thats my understanding also - TDM was asked to measure the V at the battery which is DC (unless I am mis-interpreting the request...wouldn't be the first time )
<BR> Sure, from TDM's first post it does not seem that he is familiar with that process. Fry the regulator with a jumpstart is lightweight myth. You can do better. - Jim<BR><BR>
<BR> Sure thing. "Start her up and I am getting less than 12v." . . If the meter was set to DC, what you saw sounds like an AC signal riding on the DC offset. Which COULD be caused from one or more failed rectifier diodes. But an AC reading can give some credibility to that. "AC is the 750v position on the tester, right?" . . I don't know about that. The AC volts setting might be a slide switch setting, or a few positions on the rotary dial. Do you have a picture of the dial? " . . what I think is AC output I am getting readings bouncing all over then a steady 024" . . If the meter was on AC 0-750 volts, then a display of 024 could represent the approximately 24 volt AC signal from the alternator. A sine wave with a peak-to-peak of 24V (+12V and -12V). But this is a guess. - Jim<BR><BR>
After having ridden the bike the day previous, I went to start it the following day and the battery was too weak to start but would turn over. I jumped it off a non running car. Drove the bike about 10 miles to see if the battery would charge and it died at idle. At this point it would not even click much less turn over. Battery dead. A samaritan jumped it and it ran raggedly until it died for good and pushed the rest of the way. I don't think I killed the rectifier but it may have died previously. I can access the Stator wires at the plug to the Rectifier/regulater, Is there some way to test the condition of the stator here? The TDM has a 25amp stator at 14 volts. I assume the 3 white wires are deliverying ac power to the regulator. There must be some way to measure the output.
Thanks for the help guys. I found a laymans 4 page step by step guide that includes all the tester settings at each stage. I was hoping not to have to get into the TDM innards. But I will follow the guide and see what comes up.
<BR>Hey TDM you might find this useful. http://www.bcae1.com/charging.htm Did you figure out if the meter was set to AC volts? Below is an image from the page link above. But is has no background color and it does not show up very well in the thread if you use a light-colored background theme. <BR><BR>
Yes, using a guide similiar to this one:http://www.thegsresources.com/garage/gs_statorfault.htm It looks like my RR is toast. Apparently not uncommon according to Carpe TDM. I ordered a stocker before I discovered there were heavy duty ones or even a honda conversion available. I think I will get a backup before any long trips. Tranks for the help.
That would mean a battery left with a light connected to it, would also be called AC, by your definition. Wiki has a good definition. http://en.wikipedia.org/wiki/Alternating_current I'd agree that the DC square wave could be ac with a DC offset, but it doesn't mean that they all are automaticly. To get an offset you'd have to have an AC and DC in series.
