Rectifier or alternator ?

Kjell

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Took the bike for a spin and it seems like the "no spark situation" was solved by feeding 12.8 + to the black wire on the Lucas Rita box. Engine runs smoothly. However the bike is still not charging. Tried to measure DC over the battery but the reading varies between 8-15 V measured on the battery terminal. Battery is brand new. There is a rectifier/regulator mounted on the bike. Zener diodes etc has been removed. Any ideas out there ?
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Those fluctuating 8-15V readings sound like what sometimes happens when a digital multimeter gets bamboozled by the not very smooth power generation on an old bike.

An analogue meter, with an actual needle, can give a better indication.
 

maylar

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Depends on the meter - a Fluke or HP DMM won't go bonkers, whereas a Harbor Freight cheapie might.

Are you sure your meter leads are across the battery, or are you measuring from a ground point to one battery terminal?
8-15 V (if it's real) is the range you'll see from the charging system with the battery disconnected. 8V at idle, 15 at rpm.
 

Kjell

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I am positively measuring across the battery. The DC voltage is fluctuating very rapidly. I dont quite understand why I am able to measure DV voltage and 14+ Volts without a problem on the my 66 Nova with a digital voltmeter but not on this bike
 

Kjell

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Oh and by the way the meter is still working. It has not gone bonkers even after measuring
 

maylar

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Your Nova has cleaner power.

Voltage can't fluctuate quickly across a good battery, especially with the wimpy Norton charging system - so the symptoms you have are that the meter is lying to you. People have reported that noise spikes on the power lines can make some digital meters get jumpy. That's why folks have recommended an old school analog meter, like a Simpson VOM.

See if you can come up with a different meter and if you get the same results.
 
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I have read many reports about digital voltmeters having problems when used on/near unshielded/non resistance ignition systems. I have never had it happen with my Fluke but I have seen it reported so many times that there must be something to it at least with some meters...
 

gtiller

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Try resistor plugs or caps and wound leads instead of copper ones - also make sure your test leads are not stretching across any other electronics on the bike when it’s running.

I get a stable readout on my Fluke digital multimeter, just as good as my AVO analogue meter.


The needle and coil on an analogue meter buffer some of the fluctuation, so often it appears you’re getting a more consistent reading.

Do be aware that cheaper Chinese multimeters and/or combined regulator rectifiers are both more ‘chatty’ and suspectible to electromagnetic interference (EMI) and radio-frequency interference RFI)
 

Kjell

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One final thought. Can I exclude the possibility of a defect regulator/rectifier that can cause this ?
 
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One final thought. Can I exclude the possibility of a defect regulator/rectifier that can cause this ?
From what you’ve told us, any part of the the charging system could be causing your problem, although I don’t know what problem you’re experiencing when you ride the bike.
 

Kjell

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The bike is not charging period. I leave with a fully charged battery and return with something barely enought to keep the bike running.
I'v got no lights on when I take the bike for a spin
 

Kjell

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And when we are talking about "any part of the charging system". The charging system is pretty much a rotor and a stator supplying AC and a rectifier/regulator doing the rest.
 
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you can only exclude the things that test bad~!!!!!

open the primary and see if the rotor is well centered when you roll the bike over. If the stator plates are rainbow colored that's a sign of overheating from rubbing between the rotor and the stator. SO,... you could be testing and be finding good voltage due to the battery being new, but your Rotor/stator may have over heated due to rubbing and be shorting out intermittently. That would explain the meter going back and forth

This was the situation of my bike when I bought it. The previous owner was charging it, going for rides, and having to truck it back home when the battery ran low. Eventually he wanted to get rid of it because he didn't want to work on the bike or learn, so I got it from him for $500. The rotor plates had that rainbow coloration from overheating due to rubbing from the rotor.

In the case of my bike, a '70 model, I have an ammeter wired into the harness, so I can clearly see if my stator is charging the battery when I'm riding....
 

MichaelB

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Regarding digital multimeters, Fluke is definitely top shelf, the 'Snap On' of meters.
As with Snap On, had a hard time justifying the cost.
Home Depot had Klein MM200 for about $50.00. Liberal return policy, what the heck.
LOVE IT.................. Use it all the time. No interference. The analogue sits most of the time now.
 

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