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Discussion Starter · #1 ·
This question is about a scooter (DongFang DF300stg) but its more about a general charging question/confusion I’m dealing with. This bike is not showing any VDC getting to the battery from charging system. Normal battery voltage is all you get no matter the RPM. This thing has a 3 phase stator so when I checked the output I got the same readings from all 3 windings, was around 14VAC at idle and I could rev it up and get 30+VAC going into the Regulator. Now this is where it all went off the rails for me. Coming out of the Regulator I’m getting 13-14 VDC as I would expect. But the Red and Green wires coming out of the Regulator go into another small electronic component. When I looked the part up from the info on the label, it says it’s a Rectifier. It’s nowhere to be found on the parts list either. I’ll come back to that. (And it only has 3 wires, the Red and Green from the Regulator and one RED going to a fuse then to the + of the battery) So Red and Green wires carrying proper VDC are going into this Rectifier but no VDC are going to the battery. If I unplug the Red wire that is coming out of this component and hook my meter to the spade on the Rectifier, I get a steady 13.8 VDC. When I plug it back in and sneak my probe in there it drops back to battery voltage. So I left it unhooked, and used a jumper from the terminal to the + terminal on the battery and again just battery voltage. The jumper reads 13.8 VDC but the moment I touch it to the battery + it drops to whatever the battery voltage already is.
I am really confused what this Rectifier is in line on the charging system after the Regulator. As far as the Regulator, the parts list for this bike calls it just a Regulator, not a Regulator/Rectifier. But it’s obviously taking in VAC and putting out VDC so there is a Rectifier in it. I am unsure of why this other Rectifier is between the R/R and the battery unless it’s designed to smooth out the voltage which it seems to do.
Anybody familiar with a set up like this and have a clue why the VDC are doing what they are doing? Why the second Rectifier? The only complaint about the scooter was it recently started to fail to turn over occasionally but I had a hard time mimicking the issue. Finally got it to act like a dying battery 3 times after numerous starts.
Automotive tire Hood Motor vehicle Tread Wood

REGULATOR

Motor vehicle Hood Automotive mirror Vehicle Automotive lighting

RECTIFIER
Brown Material property Wood Automotive exterior Font


RECTIFIER
 

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That rectifier is full-wave bridge rectifier and requires all 4 wires plugged in to work. There's one unconnected terminal.

IF you're getting 13.8VDC out of red wire of regulator, then no need for external rectifier, it already has one build-in. Remove rectifier and its wiring completely. Plug red wire with 13.8VDC from regulator to battery+ and that's it.
 

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Discussion Starter · #3 · (Edited)
I reached out to the manufacture and to a parts supplier about this part. Waiting to hear back before I bypass it. I can't see any wire that might have slipped off that other terminal. I suppose if anything it just would go to ground. I'm baffled why a rectifier would be in line right after the R/R and its definitely factory installed. Thanks for the reply.
 

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Discussion Starter · #5 · (Edited)
I pulled the tape/covering off the wires to get a better idea of what is going where.

The 2 Vertical spade terminals are actually the single Red + wire coming from the R/R. The Red goes into the harness then splits off into 2 green wires which are these two connections.
The ground wire from the R/R goes off into the harness and to ground somewhere.
The Horizontal Red spade coming from the Rectifier goes back in the harness and to a fuse then directly to the + battery terminal. Not sure if it splits off somewhere in the harness to another location such as the ign switch.

I took a jumper and ground that bare horizontal terminal and it didn’t help. Still get 13+VDC from that bottom + terminal if it’s disconnected and nothing when its connected.

So I tried going right to the battery from the red + wire directly from the R/R and it turns on the lights/ign the minute I connected them. I ran the engine anyway and got the same results, pretty much just regular battery VDC.

One thing I did notice if I let it sit there and run is it slowly picks up around .2 or .3 VDC over a few minute period. The battery slowly crept up to 12.89 VDC but when I revved up the engine the VDC dropped down in the 12.7 VDC range and then slowly went back up into the 12.8 VDC range.

The diodes in the secondary rectifier check out as they should.

What bweighmaster mentioned about attaching a diode makes since and appears necessary from the way the ignition turns on when I go straight from battery + to the + wire from my R/R. That tells me this must be the purpose of this component. It keeps the power from back feeding though I’m confused how/why the lights are all coming on by running battery power to the R/R.

The only place I have been able to find a similar rectifier is on eBay and it’s one of those china-pak things that takes weeks to get here. Not sure what the solution is on this one.
 

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Run red wire to diode , then to battery . Then run a fused wire from battery , to a switch , then to lights ...,
 

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I pulled the tape/covering off the wires to get a better idea of what is going where.

The 2 Vertical spade terminals are actually the single Red + wire coming from the R/R. The Red goes into the harness then splits off into 2 green wires which are these two connections.
The ground wire from the R/R goes off into the harness and to ground somewhere.
The Horizontal Red spade coming from the Rectifier goes back in the harness and to a fuse then directly to the + battery terminal. Not sure if it splits off somewhere in the harness to another location such as the ign switch.

I took a jumper and ground that bare horizontal terminal and it didn’t help. Still get 13+VDC from that bottom + terminal if it’s disconnected and nothing when its connected.

So I tried going right to the battery from the red + wire directly from the R/R and it turns on the lights/ign the minute I connected them. I ran the engine anyway and got the same results, pretty much just regular battery VDC.

One thing I did notice if I let it sit there and run is it slowly picks up around .2 or .3 VDC over a few minute period. The battery slowly crept up to 12.89 VDC but when I revved up the engine the VDC dropped down in the 12.7 VDC range and then slowly went back up into the 12.8 VDC range.

The diodes in the secondary rectifier check out as they should.

What bweighmaster mentioned about attaching a diode makes since and appears necessary from the way the ignition turns on when I go straight from battery + to the + wire from my R/R. That tells me this must be the purpose of this component. It keeps the power from back feeding though I’m confused how/why the lights are all coming on by running battery power to the R/R.

The only place I have been able to find a similar rectifier is on eBay and it’s one of those china-pak things that takes weeks to get here. Not sure what the solution is on this one.
There's some mis-configured wiring if lights go on without turning ignition-switch?

The 12.89VDC dropping to 12.7VDC with RR directly connected shows it's defective RR. To confirm, put meter in-line between red-wire and battery+ and measure how much current is actually flowing from RR. You may find intially it does charge battery, but then stops.

My conclusion: RR is bullocks.

Try to get wiring-diagram from manufacturer. Then you can check with what you have on bike.
 

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Discussion Starter · #12 ·
Run red wire to diode , then to battery . Then run a fused wire from battery , to a switch , then to lights ...,
The Rectifier in the picture is doing that already and doing a diode test on it shows its letting .4v run through both inputs and out the + terminal (which then runs thru a fused wire back to + on battery and possibly somewhere else). Reversing the flow is blocked as it should. And if I poke my meter directly on the + wire (red) from the RR, I get 13+VDC... the minute I jump that to the battery directly from the RR and bypass the second rectifier, it drops back to .2ish VDC above battery resting voltage. I don't think that's going to help.

Yeah when I use a jumper wire and bypass the secondary rectifier the lights come on. So I have to figure that is the exact purpose of this rectifier.

I have tried to contact the Dong Fang people several times by calling and email. When you call you have to leave a message and I have not heard back either way. I asked for a wiring diagram and some other questions. I've also tried finding a pdf with anything related to this bike but I can't find anything.

I just got to thinking, maybe the Stator is working but not putting out proper volts. So I unhooked it and tested the VAC and revved up I get around 45VDC across all 3 phases. When I run each wire to ground they all are grounded. Now that doesn't seem right.... And when I plug it back in and take a reading all the phase have dropped to the lower 30'sVDC range. I'm starting to wonder if maybe its putting out VAC and converting to the the correct VDC out put but once under load its not able to produce enough.
 

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AC voltage 45 volts is plenty , it is then sent into Rect./Reg. To convert to DC volts and regulate at Around 13 + volts to battery .... That's how it should work ....,
 

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...
I just got to thinking, maybe the Stator is working but not putting out proper volts. So I unhooked it and tested the VAC and revved up I get around 45VDC across all 3 phases. When I run each wire to ground they all are grounded. Now that doesn't seem right.... And when I plug it back in and take a reading all the phase have dropped to the lower 30'sVDC range. I'm starting to wonder if maybe its putting out VAC and converting to the the correct VDC out put but once under load its not able to produce enough.
You might be onto somthing...
How did you "run each wire to ground"?

In addition to measuring VAC output, there are additional tests you can do:

1. Measure resistance of each stator wire to chassis ground. Ohms = ???
2. Measure resistence of each stator wire to next: A-B, B-C, C-A. Ohms = ???
 

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Discussion Starter · #15 · (Edited)
Each stator wire indicated continuity to ground. I didn't bother looking at the read out, was just working off a beep. I used one meter probe to each wire and the other probe to ground on the battery. It's my understanding that's bad, I should not be getting continuity. I know the real test is to have the stator off the bike and check for ground to itself but I have seen online many doing the test with each output wire to a know good ground on the frame and getting OL.

I got 1.0, 1.1 and 1.2 ohms between the wires. Seems just a little high.
 

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Discussion Starter · #16 ·
AC voltage 45 volts is plenty , it is then sent into Rect./Reg. To convert to DC volts and regulate at Around 13 + volts to battery .... That's how it should work ....,
I agree, that's what is blowing my mind. When the stator wires are reconnected to the RR, it drops down to lower 30's and I still get good VDC on the output and that 13+VDC make it all the way to the last connection with the battery then its just barely above resting battery voltage. By the way, I have a brand new Yuasa battery in the bike. The other battery was weak under load testing.
 

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With engine running , there should be 13 + volts at battery positive post ... Have you checked grounds , battery to frame , frame to engine ?
 

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Each stator wire indicated continuity to ground. I didn't bother looking at the read out, was just working off a beep. I used one meter probe to each wire and the other probe to ground on the battery. It's my understanding that's bad, I should not be getting continuity. I know the real test is to have the stator off the bike and check for ground to itself but I have seen online many doing the test with each output wire to a know good ground on the frame and getting OL.

I got 1.0, 1.1 and 1.2 ohms between the wires. Seems just a little high.
Yeah, 1st test shows bad stator. It won't be able to generate much power if it's shorted to ground.
 
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