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Hello all,

So I got my bike running finally. It wasn't long before the bike started to drain my battery (I tested my new battery multiple times to be sure that it wasn't the problem). I broke out my voltmeter and this is what I found:

-When bike is running and at idle it would sit above 12v but after running the bike in gear around my neighborhood I checked it again at idle and it continued to drop until it was below 12v. At this point the bike would then die once I tried to ride it in first gear.

-Rotor puller test (I made sure to clean both rings very well): 2.2 ohms when testing inner and outer ring, 1.7 ohms when testing on the same ring

-stator test: I checked the 3 yellow lines coming from the stator (where it connects to rectifier). All 3 were consistent at 2.2 ohms.

I have also noticed that my readings keep changing. I went and checked the rotor again after about a hour and got 2.4 ohms for inner and outer ring and 1.9 ohms on the same ring (not sure if this helps at all).

I should note that the rectifier/regulator is brand new and I just replaced it. I was hoping that it was the culprit after getting some unusual diode readings from the negative lead.

I've watched a lot of youtube videos and at this point trying to figure out what else I need to replace in this charging system. Thank you for reading this and any advice is appreciated!
 

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Make sure all connections are clean and tight.

Test the voltage at the battery with it connected and engine running. Increase the engine RPM to about 3000 RPM. You should be getting somewhere above 14 volts. If not, check the voltage at the battery side of the regulator. If you get much of a different reading in these two places, you likely have defective wiring between the two points.


Test the voltage between the the stator and the regulator (AC volts). It should increase in conjunction with engine RPM. You will have to check with the repair manual to see what the proper voltage output is at a given RPM. A voltage fail means something is wrong at the stator or wiring.

Do another diode test of the new regulator. New components can be defective.

The last possibility is that the battery itself is refusing to take a charge and will need to be replaced.
 

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Discussion Starter #3
Thanks for the quick reply Dodsfall,

Here is what I found:

When I increased the RPM to 3000 it increased from around 12.2v to 12.8v. When I tested it again it still increased but not over 12v (The battery had begun to drain at this point). I should also note that with the battery fully charged it was sitting at over 12v but dropped to 11.7v when i turned the lights on (Bike still started and ran at idle).

I checked the stator as well and the voltage increased along with the an increase in RPM (I still need to check an online manual for the correct numbers).

Here is where I am really scratching my head....I did a diode check on the new rectifier and it was giving me the same unusual readings as my stock one. I take the red lead of my voltmeter and connect it to the negative end/black wire of my rectifier - then connect the black lead of my voltmeter to all 3 yellow wires of the rectifier. Instead of getting a consistent reading that should be in the 500's it will just flash a random number (1100-1600) and then go back/stay at 1 for all 3 yellow wires.
 

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Only charges at 2000rpm

I have an 82 nighthawk and I believe the charging systems are the same. The only time the battery will charge is at 2000rpm or more. You will need a battery tender if you don't ride it every day. They are fairly cheap and easy to install.
 

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OK, before I got my charging system working, I had gone through the entire harness, all the connections, and three regulators.
I had just about given up after 6 months of tinkering(do you have 6 months?)
then I found an original regulator from a shop that had closed. I put it on, and it worked. The original system is designed to pork with all original eagles, surely the main course is too much for even the most demanding of appetites...Bon Apetite!
So if you change one thing on a two wheeler, you need to change everything on one point of the circle...
 

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Discussion Starter #6
Thanks for the replies so far. Somewhat of an update:

-Turns out my rectifier is showing a normal diode test. I contacted the manufacturer and the black wire was not negative like I assumed. I should have been testing the negative end on the green wire. I should also note that the stock rectifier checks out fine too.

-I did a ohms test on the stator and got 2.1 ohms consistently for all 3 (yellow) wires. I also tested to make sure none of the coils had shorted to ground.

-My biggest question at this point would be if the readings that I have gotten from the rotor are normal. Does it matter that the readings are that high or just checking for consistency?

-Also can anyone expound on what Dodsfall suggested I test? ("Test the voltage between the the stator and the regulator (AC volts). It should increase in conjunction with engine RPM"). I just want to be sure I am connecting my voltmeter to the correct wires...

Thanks in advance for taking the time to read this and any input is appreciated!
 

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In Honda-world, green is ground, black is hot. No idea why, but that's how they do things.

If your bike's charging system has brushes and slip rings, clean them up.

Dods is suggesting checking AC volts produced by the stator. Set your meter to AC, unplug the stator connection, and check between each of the wires with each other, A-B, A-C, B-C. You should produce a lot of AC volts each time, which should steadily increase with RPM.

Charge your battery first - a good battery is required to do any charging system diagnosis.
 
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