headlight issues on 300 -12

[Peppito]

Hi!

I just bought a gasgas 300 -12.
It was in bad shape, but after some hours in the garage it?s starting to look like a bike again

But if got some problem with the head and tail light.
The previous owner has installed a rectifier and battery, i have like 14 volts dc from the battery, thats all good.

But att the headlight i have AC. If i start the bike the head and tail light has around 12 volts. But after like 1 minut if i rev the bike it decrease to around 8, and the lights dosen?t shine so bright anymore And after like 2 minute i have around 6 volt in the "front".

Anyone have any idea what i should do?

Thanks!

 

[Neil E.]

First thing is to check the headlight bulb wattage, should be no more than 35W if it has a stock bulb.

Second thing is to figure out if the battery is good. A worn out battery may charge up to the required voltage, but does not have any capacity to maintain it's output.

Charge the battery off the bike, then connect a tail light bulb to it using the brake filament. It should be able to keep the light bright for quite a while. If the light output is good for 20 minutes, the battery should be OK.

Charge the battery again and test your headlight. If it still has a big voltage drop, you will need to test all the connections and grounds. Run temporary wires from the battery directly to your headlight bulb. If there is only slight voltage drop then for sure you have an issue like broken strands near the headstock, etc.

 

[Neil E.]

My previous answer was based on your headlight operating on DC voltage.

You may have to trace wires and make a diagram to determine what the previous owner modified. Your headlight might be connected to AC, but I don't know what would create that kind of voltage drop as the revs are increased. Normally you get more output at higher revs. When an AC voltage regulator fails, your bulbs burn out from excess voltage.

What is the physical condition of the stator? Corrosion will reduce output.

 

[Peppito]

Thanks for your answer Neil.

The battery seems fine, and the regulator for the battery seems to work good also. Gonna try with a led light tomorrow on the DC side. I think i only used the battery for a led light that i haven?t got yet. So nothing is connected to battery.

You have right i have AC at the headlight. I gonna measure the voltage tomorrow ( can?t start the bike, because it?s middle of the night in sweden directly on the yellow wire from the stator.
I haven't looked at the stator yet, will do tomorrow.
Here in sweden the enduro people always talking about "solder the stator" if i understand it correctly the 2 coils will work as one. Could this have something to do with my problem?

Thanks again

 

[Neil E.]

Don't "solder the stator" unless you're repairing a broken connection. The yellow (and ground) provides AC power for lighting. This is regulated. The white wire (and ground) provides slightly higher AC voltage to be rectified into DC for battery charging.

If you measure voltage at the yellow wire, it should hold steady around 12 to 13 VAC as the revs increase. If the regulator is unhooked, you will see it increase dramatically.

A bad connection in the system will act like high resistance and possibly heat up causing reduced current flow and a resultant voltage drop. You have some investigation to do. Check all connections and grounds.

 

[Peppito]

Hi again!

This morning i tested this: Battery out, but the aftermarket rectifier still in with the white cable to + and - grounded in the chassi.
Then i measure the yellow cable direct from the stator. I had only like 1,5 volts AC. Strange, so then i removed the ground cable that goes to the rectifier. Then i hade like 22-30 volts, plugged in the original regulator and every things works like a charm! Steady between 12-13 volt.

So thats good.
But i wonder why i can?t use both system? It?s something wrong with the ground? Or is the aftermarket rectifier/regulator broken?
But i think it ok, when a measure the DC system on the battery i got a charging around 14 volts that seems ok to me.
I really want to use both system.

 

[Peppito]

Hmm! I was sitting with a cup of coffee and thinking my brain outs :=)
The aftermarket rectifier for AC, should that one be grounded? If i just connect that cable to the - at the battery and to the lights? should that work?

 

[Neil E.]

You can run a mixed system but the output from a fullwave DC rectifier must not be grounded. This is because the stock stator windings are already grounded and the DC rectifier will not work correctly if it's output is grounded.

In review: the single phase stator has three connections. Ground, yellow and white. AC output from yellow to ground, AC output from white to ground.

AC on yellow regulated only, AC on white rectified and regulated for battery charging. AC after rectification becomes DC, connect it directly to your battery.

The only issue is that an estart bike must be done differently because of the starter motor ground. All the discussion so far is based on a standard non-estart machine.

 

[Peppito]

Great! I think i got the problems solved! Thanks Neil!

 

[Peppito]

Hi again Neil!

After som more digging in the electrical system on my bike, i assume the other owner has wired the t/t rectifier with no floating ground, but have kept the original rectifier. But that sorted out now i think
But if i want to have ac for my stock headlight and brake light and DC for my helmet and extra headlight, should i ground the t/t rectifier? Because now it?s sits under the plastic battery holder.

Thanks

 

[Neil E.]

I can only assume that the original "rectifier" is actually a voltage regulator. If it is a rectifier, it may only be doing voltage regulation. A rectifier does both regulation and rectification; a voltage regulator does only regulation.

In your case do not ground the trailtech r/r. It will supply floating/isolated DC for your extra lights just fine. The extra lights get power from the r/r without the lights or the r/r being grounded.

I use a split system on my estart bike. I have my heated grips running on AC and everything else on DC.

 

[Peppito]

Hi. Of course the original is only a regulator!
Thanks for your answer! Then i think my Trailtech is broken, i have voltage AC in but nothing on the DC side.
i?m not surprised, it looks like garbage

 

[Neil E.]

Is the DC side connected to a battery? This is a requirement for the r/r to function.

 

[Peppito]

I have measured with the r/r connect to the battery, but i have only like 12,8 volt there. If i measure the battery with the bike off it?s 12,8 so i think the r/r is broken

 

[Peppito]

Hi again

Was just out in the garage and did a measure again.
The r/r will not charge the battery. I hade 12.17 v in the battery, connected it to the bike, but it on idle and reved a little. Still 12.17v.
I will attach 2 images of the r/r.

From the beginning one yellow wire was connected to the white from stator, it still is.
The other yellow wire was connected to frame ground, right behind the original regulator.
And black and red connected to the battery.
But when it was connected like that the r/r was charging the battery with about 14v. The only thing i have done is disconnect the ground cable from the frame. But i have touched the little voltage dial (when the ground was still connected), when i turned the dial the lights connected to AC become more stable. Unfortunate i did?t measure the voltage after i did that. Maybe i broke it when i did that. And under all of this i notice that the AC power dropped after a while, and the i disconnected the ground to the r/r.

 

[Neil E.]

From the beginning one yellow wire was connected to the white from stator, it still is. The other yellow wire was connected to frame ground, right behind the original regulator. And black and red connected to the battery. But when it was connected like that the r/r was charging the battery with about 14v.

This part of your post makes sense; that is how it's supposed to work. The rest of your post makes no sense. Certainly if the r/r is not working there will be no change in battery voltage. The small dial is for voltage trimming and you need to be careful with it (fragile). It should not matter if the r/r housing is connected to chassis ground; does something change when it is grounded?

The wire entry at the r/r looks rough, maybe you should get a new r/r. I don't see how adjusting the dial can have any effect on the AC voltage unless the r/r is faulty.

 

[Peppito]

Ok. But i thought that the other yellow wire from r/r shouldnt be grounded to the frame. But when it was i had like 14 volts to the battery so if is the correct installation, maybe its so simple that the r/r is broken and thats why my AC-voltage dips when Reving.
It looks like the r/r has been connected like that for awhile

No difference when i ground the chassi of the r/r.

 

[Neil E.]

To review: AC power comes off the stator at the yellow wire (medium voltage) and the white wire (maximum voltage). The other side of the circuit for both is chassis ground (the bottom end of the stator winding is connected to the engine case/motorcycle frame).

For battery charging we want maximum voltage thus we connect the INPUT of the r/r to white and ground. Only the input OR the ouput of a fullwave rectifier can be grounded. Therefore because of the stock stator ground you must NOT ground the r/r output. This means the black and red ONLY go to the battery. This is the correct installation.

I would not be concerned about a slight drop in AC voltage. At some point the stator current is being consumed so the AC voltage may drop a bit. This is likely due to the output that is going into battery charging or being used by your lighting.

On a single phase system the main concern is normally clipping voltage so that bulbs don't burn out. At a certain point if you have too much load on the stator you will always get a voltage drop. The system just doesn't produce that much power. If you get 14VDC to the battery and it stays charged, that's what's important.

If you have a significant drop in AC voltage, then your stator is in poor shape or your r/r is shorting out somehow. I'd replace the r/r first since it costs less than the stator. Remember that all connections must be sound for the system to work right. Corrosion can be a big problem. There isn't anything more I can advise you on, it may be time to spend money on parts.

 

[Peppito]

To review: AC power comes off the stator at the yellow wire (medium voltage) and the white wire (maximum voltage). The other side of the circuit for both is chassis ground (the bottom end of the stator winding is connected to the engine case/motorcycle frame).

For battery charging we want maximum voltage thus we connect the INPUT of the r/r to white and ground. Only the input OR the ouput of a fullwave rectifier can be grounded. Therefore because of the stock stator ground you must NOT ground the r/r output. This means the black and red ONLY go to the battery. This is the correct installation.

I would not be concerned about a slight drop in AC voltage. At some point the stator current is being consumed so the AC voltage may drop a bit. This is likely due to the output that is going into battery charging or being used by your lighting.

On a single phase system the main concern is normally clipping voltage so that bulbs don't burn out. At a certain point if you have too much load on the stator you will always get a voltage drop. The system just doesn't produce that much power. If you get 14VDC to the battery and it stays charged, that's what's important.

If you have a significant drop in AC voltage, then your stator is in poor shape or your r/r is shorting out somehow. I'd replace the r/r first since it costs less than the stator. Remember that all connections must be sound for the system to work right. Corrosion can be a big problem. There isn't anything more I can advise you on, it may be time to spend money on parts.

Thanks for your excellent answer and for helping a rookie
Ok, But the other yellow wire from the r/r that was grounded when i bought the bike, should it be grounded or not?
That my biggest headache right now.

 

[Neil E.]

Assuming the yellow r/r wires are the INPUT to the r/r, then one of them MUST be grounded (other r/r yellow wire goes to the stator white wire). It's the only way whereby the r/r will be connected to the stator output.