Charging System problem

[LatencyXR]

Bike has a Chinese engine, thought I'd throw that out there before we start.

Using a multimeter on battery when bike is idling and there's zero effect voltage doesn't raise, even when revving bike to 5,000rpm as manual suggested still nothing.

Tested alternator for resistance and the ground for parasitic draw and everything was fine with the alternator result are resistant 0.9 ohms (took the 0.1 off from meter pins) which doesn't exceed the levels for replacement, tested for ground and that was perfect .. zero spikes.

Which leaves the regulator.. for the life of me I can't seen to understand how to test this! I got reading when key was on at 12.4v but forgot how I did it. How do you test the regulator with multimeter?

Basically this question is if it's not the charging system then it's the battery, a full charge on the my AGM is around 13.4v but once the key is turned to on the battery falls down to 12.3v then once key is off climbs up to 12.8v and stays there!

Trying to figure out if it's the whole charging system plus the battery or just the battery!

Probably made zero sense but I'm hoping someone understands it.

Thanks
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Honda CB300R - More 125's then the heart can handle!

[Nobby the Bastard]

You said alternator and you said regulator. An alternator has no need for a regulator as it's output is 12v DC.
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trevor saxe-coburg-gotha:"Remember this simple rule - scooters are for men who like to feel the breeze on their huge, flapping cunt lips."
Triumph Sprint ST 1050

[stinkwheel]

You can't test a reg/rec with a normal multimeter, it has componants that react to loads in different ways and a multimeter doesn't put that much load on.

So it's a process of elimination. You check the stator windings and you check the connections to and from it. If they are all fine, the reg/rec is suspect.

You've done the static test of the stator. You can also do a dynamic output test using your multimeter on volts AC connected to the stator output with the reg/rec disconnected. I don't know what sort you have fitted because you are inexplicably reluctant to say what make and model of bike/engine it is so you'll need to work that out for yourself because there are a couple of different ways it could be wired.

If you're getting a good AC output going to the reg/rec from the stator and good continuity to the battery and earth from it, it's faulty.
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“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[LatencyXR]

Yes sorry

Manufacturer: Brixton Motorcycles

Make: Cromwell BX125X

Engine: 157FMI-C

Stator wires are: 3 black molex, 1 green and 1 purple/blue wire. (Think it must be blue! Just faded)

Reg is just a 5 wire, 3 yellow, 1 red and 1 black ground

Battery: Motobatt 12v 11ah
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Honda CB300R - More 125's then the heart can handle!

[Nobby the Bastard]

PPresumably the 3 black wires actually connect to the 3 yellow wires going to the regulator and the two coloured wires are actually the coil that triggers the spark.

You can check the voltage (in AC) across each pair of the black wires whilst it's running but obviously it will need to be plugged in because spark will stop if unplugged. Expect anything up to abou 30v AC across each pair of the three.

You need to be getting that on all three combination of pairs.
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trevor saxe-coburg-gotha:"Remember this simple rule - scooters are for men who like to feel the breeze on their huge, flapping cunt lips."
Triumph Sprint ST 1050

[stinkwheel]

I'd be inclined to test the AC output at the reg/rec connector (with the reg/rec disconnected), so you can confirm the power is getting that far. As above, a decent and roughly equal AC voltage between each pair.
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[LatencyXR]

Did a AC test on all 3 meter was ready each around 35.0 .. does that look alright?
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Honda CB300R - More 125's then the heart can handle!

[LatencyXR]

Awesome so test the reg/rec can be done on AC too .. it's really confusing seeing as the wires are different colours on each .. and the wiring diagram is in Chinese
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Honda CB300R - More 125's then the heart can handle!

[Nobby the Bastard]

[Nobby the Bastard]

[stinkwheel]

Sounds like you need a new reg/rec.

The stator produces AC and as you've seen, up to 35V on each phase.

The regulator rectifier rectifies the AC into DC then regulates it to around 13-14V.

If there's 35v going in on your yellows and the voltage doesn't go above resting battery voltage when the engine is revved, either the reg/rec isn't connected to the battery or it's dead.
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[LatencyXR]

Even though the wiring diagram is in Chinese.. the green and blue wire are spark and back brake light. I'll test the reg/rec tomorrow but the stator looks okay, good readings.

Probably just a charging issue with the battery previous owner started he never changed the battery! Bikes around six years old so maybe a new battery. That doesn't explain why it won't charge but hopefully tomorrow then reg/rec gives a clue.

Thanks!
____________________
Honda CB300R - More 125's then the heart can handle!

[Nobby the Bastard]

OP will need to explain whether or not the output wires (typically red and black) on the reg are on a separate connector to the input.

If they are, unplug there from the bike and check voltage across it whilst the bike is running.

If it's not separate, it could be the regulator, it could be the wiring/connectors.

Probably the regulator, though.
____________________
trevor saxe-coburg-gotha:"Remember this simple rule - scooters are for men who like to feel the breeze on their huge, flapping cunt lips."
Triumph Sprint ST 1050

[Nobby the Bastard]

[LatencyXR]

Right my bad, I test the reg/rec a few days ago according to my Google search history.. I was getting a 12.1v reading on the reg that was just after turning engine off! Google didn't really give me a answer to my question clearly .. probably the reg/rec then. Seems about right!

Cheers for the help and the knowledge
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Honda CB300R - More 125's then the heart can handle!

[Nobby the Bastard]

In order to test the output of the reg you need to disconnect either it or the battery. Otherwise you will just be measuring the output of the battery if the reg is fucked.
____________________
trevor saxe-coburg-gotha:"Remember this simple rule - scooters are for men who like to feel the breeze on their huge, flapping cunt lips."
Triumph Sprint ST 1050

[LatencyXR]

[LatencyXR]

This is the reg/rec for the bike in question

3 yellow, 1 red, 1 black.
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Honda CB300R - More 125's then the heart can handle!

[WD Forte]

Bike has chinese engine?
Brixton my arse
Its a rebadged and overpriced chinese bike FFS with a typical cheap chinese RR found
on a million chinese bikes.
You can test them with a meter but only the rectifier diodes
the regulator has to be actively tested but that's easy enough

The tests should take all of 5 minutes if you take your time
I cba to write it all up again. JFGI
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bikers smell of wee

[LatencyXR]

Same bike, different design, there all shit but fun to run into the ground, found a video, I'll follow it like a pro!
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Honda CB300R - More 125's then the heart can handle!

[jeffyjeff]

Here is a flow chart that might help.
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History shows again and again how nature points out the folly of men - BOC

[that_impulse_guy]

you've eliminated everything else, the reg/rec is like...£5 i think on ebay (figure of speech...theyre about 12-15£). its a pretty generic thing at this point in time.
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[Lone-Wolf]

[A100man]

[Nobby the Bastard]