But lets say we have a alternator producing 100 watts @12 volts AC. With no lights turned on, all that 100 watts has to go somewhere. This 100 watts gets shunted to earth doesnt it. So doesnt that mean the regulator has to be capable on handling the process of dumping 100 watts. Then lets say we turn on one 50 watt light, then in theory the regulator only has to dump 50 watts as the other half is being used by the globe. Thats just what i think anyway. Most of these bikes will producing anthing up to 30 or 40 volts AC unlregulated.

When i have seen regulators advertised for sale, most will specify the rating in watts in terms of what it can handle dumping. If your alternator is putting out more power than the regulator can dump then you are required to keep a load on the alternator and use some of the power. In most cases this just means you have to run with your lights on during the day as well.

 

Didn't he said that the alternator has a coil specially dedicated to the lights? Is even necessary to regulate that voltage when the lights are turned off?

 

re: enduro250z

No the alternator simply doesn't put out more current than it needs to. If you load the alternator down with 100 watts, it will take 100 joules per second of energy from the engine, plus friction. If you don't load the alternator down it effectively becomes a weight on the engine's crankshaft but nothing else, it doesn't have to shunt any current away. If you connected a 12V 5W light bulb and a 12V 35W light bulb, you will find they consume different amounts of energy, not the same amount.

At least, that's how I understand it. Look up regenerative braking; in newer hybrid cars, a generator is used to assist the brakes, and this charges the batteries, because the generator slows down the wheels by means of converting kinetic energy to an electric current. However the generator only takes as much energy as it needs to produce the amount of electric current being drawn by the batteries/charging circuit. If the batteries are full, the generator turns easily; if the batteries are empty, the generator draws more energy. Also look up motor braking, where instead of providing energy to batteries, the energy is wasted as heat. Of course both systems are supplemented with traditional brakes.

Of course, if the alternator is producing a high voltage, then more power is dissipated. But then it gets a bit difficult. If your loading of the alternator is producing a lower voltage, then your power dissipation in the pass transistor will be low (mostly in the alternator itself) and you can use a smaller transistor. But if it really is producing 30 or 40 volts a.c. then the series pass transistor I suggested will have its maximum Vce exceeded and this will cause it to prematurely fail, it will also contribute to very high power dissipation, about 133 watts for 40 volts a.c. with a 3 amp/12 volt/36W light bulb.

 

Yes its necessary to regulate the power comming from the coils or coil if there is a regulator connected. What we use to do when we had modified rewound stators and when setting up the bike to run in Motocross when no lights are need and are infact removed from the bike, is since the regulator cant cope with dumping the full 250 watts, all we have to do is disconnect the regulator. So no power goes to the regulator so it cant be damaged by maximum power. When the regulator wasnt connected i guess the power just went into an open circuit as the headlight was taken off.

Another reason a regulator is required in most cases is because lets say you have a stator wound for 100 watts @ 30 volts unregulated. Even if you have head and tail light turned off in the day, the brake light (usually 21 watts) is still needed during the daylight. With no regulator, most/all the power will go to the brake light and it will instantly blow the globe. I know that for a fact.

The regulator doesn’t stop power coming out the alternator. Its producing power all the time. The Ac regulator is just there to only pass one the required power needed to the lights and all the excess is dumped by the regulator. That’s what I believe anyway. The power rating of the reg just means what the regulator can handle disposing off.. That’s why ive been told by some bike electrical experts that if you’re the regulators power handling is less than what the alternator is putting out then you either need to run the lights all the time or fit a higher rated regulator.

Anyway I agree that if you have a alternator producing only 60 watts, then you can build a regulator with not such a big heat sink and if you want to run with your lights off in the day, you just need need make sure the regulator can handle passing 60 watts to earth. I personally would over build it and maybe make if for 80 watts and then you would no for sure the regulator can take it.

On bike alternators you can have a stator with a number of poles all wound for lighting or you can have just one or 2 indvidual lighting coils.

I have started pulling apart my other old custom made AC regulator and i am finding some interesting components inside. There is definitely more components inside then i thought. i will report back on Sunday maybe when ive finished identifing everything.

 

By 'power', do you mean 'current'; because an alternator only produces an electric current, it does not dissipate power (ideally, some will be wasted as heat in the coils.)

Have you done any measurements with a multimeter? Try measuring the voltage when there is a lamp attached (through a regulator and briefly without) and when there is no lamp attached.

Note that if the lamp is off the pass transistor does not 'dump' any power. The dissipation is at most a few hundred milliwatts, due to base current. The transistor does not need to waste the power that the lamp may use or the alternator may produce. Think about a power station; the generator there uses more energy if there is more demand, otherwise saving energy would be pointless and the utilities might as well charge us a fixed rate.

 

Ok, we dont seem to be agreeing here, but im listening. So your saying that if there is no power being used from the alternator, that there will only be a tiny amount going out through the regulator to earth and it just doesnt have to be able to handle dumping the full power?
i have always been told and always understood that if you are not using any of the alternators power and the regulators rating is less than the alternators, then the regulator is going to be damaged as it cant handle dumping all the power. Thats why ive been told to disconnect the regulator when removing the lights from teh bike for motocross so the regulator doesnt get damaged. If the regulator is rated higher than the alternator then you have no problems and it will be able to cope with disposing of the power. Ive been told that by somone who makes regulators. I know what your saying about the power station thing but dont think they are the same as whats in a bike.

 

Here is an interesting article on automotive alternators.

http://www.allaboutcircuits.com/vol_6/chpt_4/8.html

A quote from it:

Short-circuit any two of the three-phase line wires and try spinning the alternator. What you should notice is that the alternator shaft becomes more difficult to spin. The heavy electrical load you've created via the short circuit causes a heavy mechanical load on the alternator, as mechanical energy is converted into electrical energy.

It might help you understand why shunting away excess power from the alternator is unnecessary.

 

I think we maybe getting confused with each other here

No the alternator simply doesn't put out more current than it needs to. If you load the alternator down with 100 watts, it will take 100 joules per second of energy from the engine, plus friction. If you don't load the alternator down it effectively becomes a weight on the engine's crankshaft but nothing else, it doesn't have to shunt any current away. If you connected a 12V 5W light bulb and a 12V 35W light bulb, you will find they consume different amounts of energy, not the same amount.

I never said the alternator has to dispose/shunt the power away. That is the regulators job. My point is solely about the regulators shunting capability. You can buy them in different ratings. Some can shunt 50 watts, some 100, some 150, some 200 etc.

If you had a 200 watt alternator you wouldnt fit a 50 watt regulator. As soon as you stop drawing the alternator the regulator would quickly cook. Thats why you would fit a 200watt or higher regulator.

 

Those alternators in that article are nothing like whats in the bikes suzukiman and i are dealing with with. They are a different sort of alternator. Besides being 3 phase they are limiting what comes out of the alternator or what the alternator produces. Yes this system can be found on bikes (mostly road bikes with big high out put alternators) but its not what is found on 99% of trail bikes. They do not use alternators with brushes and they are not limiting whats comming out the alternator with the regulator. The output of our systems is proportanate to engine speed. i am still 99.9% sure that the bike alternators im dealing with which are just a bunch of coils on a plate with a flywheel with magnets inside it that spins over stator coils, is producing power all the time as long as the engine is running.

I try to think of it like this.

in the 3 phase brush type car or bike alternator, the regulator in these systems is also a rectifing to DC type, and they need to be able to handle the power that is being passed through the alternator when there is a draw and the handle the heat due to the rectifiing process. When there is little or no draw, not much power reaches the regulator/rectifer as it is regulating/preventing the alternator from producing current thats not needed.

In the basic AC system, when there is a lot of draw on the alternator, the regulator is not having much pass through it and doesnt have to do much of a job apart from keeping voltage to 13 volts if you had a high enough wattage globe and rode everywhere at high revs, you will find that you can disconnect the regulator and the globe wont blow as there is not enough power to properly run the globe, but what is there, is thrown straight at the globe. Ive even tried this before.But when there is little or no draw, thats when the regulator really starts to do its job. It has to do something with all the current being thrown at it.

Even on many old bikes up to the early 80's including some of mine had no regulators. Its was a cost cutting exercise at the factory. Every globe had to have wattages that added up to the alternators out put at specific revs. if one globe blew then all the rest did. Its not a very good set up.

So i know on one of mine, it produces about 20-24 volts unregulated with no lights on, but when you have the lights on, enough current is used and the voltage then drops down to 6-7 volts (bike is a 6 volt system) so in that set up a regulator in theory is not needed. Its never really true though as many guys still blew globes from really high revs and if you fitted a replacement globe that was a lower wattage than originally specified it would stuff the whole system up as you would get increased voltage at the globe which would blow them.

Anyway i guess we might be getting a little off topic now. I will have to sleep on it i think.

 

Didn't he said that the alternator has a coil specially dedicated to the lights? Is even necessary to regulate that voltage when the lights are turned off?

No, its not necessary to regulate it. Its not being used, but it has to go somewhere. The regulator is there just to shunt the power to ground. As i said before, if you wanted to you could disconnect the whole regulator if you wanted to but as soon as you braked the brake light globe would blow and if you turned on the head/tail light they would blow aswell. Thats why the regulator is always required so the brake light wont blow. Try to think of the AC regulator as a shunt or a gate. It doesnt control what is comming out the alternator. Engine speed (revs) controls what comes out the alternator. The regulator controls what the alternator supplies to the lights. If there is an excess not need by the lights, the regulator does its job and 'deals with it' by shunting it to ground. Its a very simple, basic system really.

I can understand why people only familiar with DC systems or 3 phase car/truck type alternators systems may have trouble understanding this though. The sort of AC system i have been trying to explain is really only common to trail bikes, vintage bikes and small engine applications. What Tom66 is saying is applicable to systems where they are limiting what the alternator is actuallly producing.

 

Any idea what the frequency of the alternator output is when the engine is running at redline RPM?

One of the problems I run into during simulation is the switching speed limitations of SCRs, TRIACs and transistors.

Basically, you want the switch to either be ON or OFF, as if you're regulating in a linear mode, you will be dissipating a LOT of power in the regulator. That's one big problem with the 2N3055 schematic posted earlier. Another problem with it is that the Zener will get blasted right off the board within a few cycles, as it'll probably be dissipating a hundred or so Watts of power.

 

I'm not too familiar with bikes but I did play around a bit with snowmobiles electrical system and it uses the same regulator discussed in this thread. (most older sleds did not have a battery)

This online supplier has a variety of VR's
http://www.mfgsupply.com/SnowRegs.html

I have one of these somewhere but can't find it right now, it's basically quite simple, 2 or 3 components (triac, TO-220) and a diode, maybe a resistor, cant remember, but I do have the original 1973 patent document that has a schematic if that helps.

I used the 18VAC output of a transformer to test these with.

 

Well, I guess I'm kind of out of my league here; I wouldn't know the difference between a bike and car alternator if I was hit by either. But I still don't know about excess current being shunted away. It's like when you turn the heating on in a car. The average miles per gallon will go down because the alternator is using more energy to run the heater and charge the battery; the MPG will not stay the same as if the excess current is being shunted away.

What happens if no regulator is connected? Does the alternator overload?? That doesn't make sense to me. Current is not 'thrown' at a device; a device draws current (ideally as a resistive load) as required and no more.

 

Any idea what the frequency of the alternator output is when the engine is running at redline RPM?

One of the problems I run into during simulation is the switching speed limitations of SCRs, TRIACs and transistors.

Basically, you want the switch to either be ON or OFF, as if you're regulating in a linear mode, you will be dissipating a LOT of power in the regulator. That's one big problem with the 2N3055 schematic posted earlier. Another problem with it is that the Zener will get blasted right off the board within a few cycles, as it'll probably be dissipating a hundred or so Watts of power.

You have just touched on one of the big variables. Unfortunately I do not have a scope, but the stator may have 1 coil with 2 poles, up to 6 coils with a single pole is also quite common I think, but could have as many as up to 18 and the rotor may have two, three or more fixed magnets depending on the amount of coils/poles. The rotor is then spinning at engine RPM's which may be anything up to a good few thousand depending on the type of bike and engine.

Then the output voltage also rises and falls with the RPM's so that is a second variable, but easier determined. It can be assumed to be higher or close to 12V AC at idle and up to 30V AC at redline.

With the factory AC regulators a slight flickering of the headlight can be seen at idle, but goes away as soon as the RPM's go up slightly. This may be due to the alternator design, but also may be due to maybe shunting half wave?

 

Well, if the output of the alternator is clamped at a certain voltage level, the average current is going to vary due to the slope of the AC input. If you have a 12v P-P AC signal and clamp it at 12v, you're going to wind up with about .707 times the peak. However, if you have a 30v p-p signal, you'll wind up with much higher average current.

That's why I'm thinking rectification, and then a switching buck-type regulator. Even though the alternator is supposedly a higher impedance type than an automotive alternator, why use shunt regulation when a bit more complex circuit would result in less power being robbed from the engine, and dissipated as heat in the alternator?

It's up to the OP what they want to do. Just trying to make some suggestions here.

I think perhaps a full-wave bridge, then a filter cap maybe with a Zener clamp to ground limiting peak voltage on the cap, then a switching regulator to supply head/brake/turn lamps would give pretty good performance.

As I've mentioned a few times already, I'm not very familiar with thyristors aka TRIACs and SCRs. The most common SCRs are designed to operate with 50/60Hz up to perhaps 400Hz AC. I am uncertain about TRIAC/SCR operation at frequencies in the 10kHz to 70kHz range; the frequency range is simply a wild guess. Some of the older trials bikes had long-stroke single-cylinder engines that had oodles of torque; bump the throttle and pop that front wheel right in the air over obstacles. I'm uncertain if that's the kind of bike we're talking about; I simply don't have time to re-read all 10 pages of this thread.

 

Sgt Wookie,
These are mostly trail bikes like Honda XL250, XR500 etc, but this exact same method is used on some scooters as well.

What do you think of the schematic on post #75 does it seem to be correct?

I understand where you are going with the idea of linear regulation. On the bike forums that has been debated quite a bit by the electronic bikers!

We are trying to keep away from heat, size and complexity (heatsink/enclosure) as far as possible. OK in electronics 6 components compared to 3 is not more complex!

You probably know this, the latest OEM bike shunt R/R are now FET controlled instead of SCR and have a higher current rating up to 50A.

Thanks for your interest in our project.

 

What happens if no regulator is connected? Does the alternator overload?? That doesn't make sense to me. Current is not 'thrown' at a device; a device draws current (ideally as a resistive load) as required and no more.

Yes many snowmobiles have the same system.
There is no need to complicate things here. As long as we have no LED’s, HID lights or anything requiring DC we do not need to rectify the AC source to AC. Another advantage with AC is its high power output. As soon as you run it through a rectifier you will loose 1/3 of the power. If you have a alternator producing 120 watts AC, 12 volts at 3000rpm, if you run all that through a combined single phase regulator rectifier the end result is you loose 40 watts through rectification and will end up with 80 watts usable power instead of 120 watts. I know that as a fact.

If no regulator is connected and the current from the alternator is higher than whats being consumed, the globes will blow from over powering, its as simple as that.

If you disconnect the lights at their connections, lets say at the back of the globes on the sockets, and disconnect the shunt regulator, the alternator power just goes open circuit. It doesn’t not reverse around and go back into the altenator and overload it. That seems to be some misconception, people can think you can overload the alternator but it just doesn’t happen. Also people thing if you put a too many high powered lights of what ever on the bike that’s its going to over draw or overload on the alternator. Again that doesn’t happen. Example if you try and run a 100 watt globe off a 50 watt alternator, there just simply wont be enough power to light the globe up properly, there will be a big drop in voltage and the globe will be dull and not be lit to is full protential. Ive done all these experiments.

 

Yes its necessary to regulate the power comming from the coils or coil if there is a regulator connected. What we use to do when we had modified rewound stators and when setting up the bike to run in Motocross when no lights are need and are infact removed from the bike, is since the regulator cant cope with dumping the full 250 watts, all we have to do is disconnect the regulator. So no power goes to the regulator so it cant be damaged by maximum power. When the regulator wasnt connected i guess the power just went into an open circuit as the headlight was taken off.

Another reason a regulator is required in most cases is because lets say you have a stator wound for 100 watts @ 30 volts unregulated. Even if you have head and tail light turned off in the day, the brake light (usually 21 watts) is still needed during the daylight. With no regulator, most/all the power will go to the brake light and it will instantly blow the globe. I know that for a fact.

The regulator doesn’t stop power coming out the alternator. Its producing power all the time. The Ac regulator is just there to only pass one the required power needed to the lights and all the excess is dumped by the regulator. That’s what I believe anyway. The power rating of the reg just means what the regulator can handle disposing off.. That’s why ive been told by some bike electrical experts that if you’re the regulators power handling is less than what the alternator is putting out then you either need to run the lights all the time or fit a higher rated regulator.

Anyway I agree that if you have a alternator producing only 60 watts, then you can build a regulator with not such a big heat sink and if you want to run with your lights off in the day, you just need need make sure the regulator can handle passing 60 watts to earth. I personally would over build it and maybe make if for 80 watts and then you would no for sure the regulator can take it.

On bike alternators you can have a stator with a number of poles all wound for lighting or you can have just one or 2 indvidual lighting coils.

I have started pulling apart my other old custom made AC regulator and i am finding some interesting components inside. There is definitely more components inside then i thought. i will report back on Sunday maybe when ive finished identifing everything.

Then just put the regulator after the switch that turns the lights on. If the coil just power the lights, it doesn't makes sense to regulate it to 12v always, as any excess power will be turned into heat, and energy is coming from your gas tank. The only problem would be if the switch cannot handle the extra current.

 

Then just put the regulator after the switch that turns the lights on. If the coil just power the lights, it doesn't makes sense to regulate it to 12v always, as any excess power will be turned into heat, and energy is coming from your gas tank. The only problem would be if the switch cannot handle the extra current.

Yes that is the obvious way to do it and can easily be wired other side of the lights on/off switch.

OK we are now only looking at off road bikes, but if these bikes are used on the road and specifically for the scooters then in some countries the lights must always be on and for some years some bikes for those countries did not come out with an On/Off switch for the lights, just a High/Low beam switch. Other countries again had an On/Off switch.

Manufacturers then opted to standardise and some had them in circuit continually and again those were very small units which did not over heat at all.
I think we are overreacting as to how much current is sunk from the lighting coil by the regulator. In actual fact the lighting coil most likely would not be capable of putting out more than 5 -7 Amps even less in some cases. To make the AC regulator robust enough and interchangeable for any type of use it would be better to build it to be able to work continuously with headlamp on or off. If someone then does forget or for whatever reason does not to put the lights on the regulator would not be stressed.

The easiest part will be to change components for higher and lower maximum current rating, but at the moment we want to try and find a schematic that will do the job in a simple way, is very small and lends itself to easy installation on a bike that does not have much space for such things. We defintely do not want to reinvent the wheel here, its just not worth the effort.

So all your help and inputs are again much appreciated. It seems as if we have some ideas on the table from some of you. Keep the thoughts, especially the schematic coming as they speak a 1000 words!

 

Then just put the regulator after the switch that turns the lights on. If the coil just power the lights, it doesn't makes sense to regulate it to 12v always, as any excess power will be turned into heat, and energy is coming from your gas tank. The only problem would be if the switch cannot handle the extra current.

No that wont work as you go to have the regulator before the brake light, although in many countries you can have your headlights off in the day but you still need your brake light to work. Think about it as if you were in a car and driving around with the lights off. When you brake, the brake warning light comes on to warn drivers behind you durign the day still.

Ok i agree, we are not trying to or need to re-invent the wheel here. The system we are trying to explain and are using is a proven, well known, commonly used system found on many bikes and snowmobiles etc. I have drawn it out below. You can see how if you turn the head and tail light main switch off, when you press the brake light switch connected to the hand or food brake the brake light comes on and it wont be blown as the regulator is connected before hand. This is the set up, it works and we dont need to change it. I dont see any reason to get stressed about or anything. Bottom line is you can buy regulators for these applications to do the job we want to do and are ment to be connected at the location as in my drawing.

Now you might ask if we can just buy these regulators then why not?

several reasons

I believe suzukimans main reason is that he just wants to try and make one thats cheaper than buying one.
some of my reasons are
I would possibly like to learn something and have some fun making my own as a project, most likely cheaper than a bought one. And also the highest power handling AC reg i can seem to find is around 200 -225 watts, so i want to see if i can custom make some of mine to be able to handle some more power, maybe 250 watts at this stage that could all come down to the rating of the transistor if used. I dont believe the heatsink has to be huge as the regulator would be bolted to bike chassis which would take away much of the heat. Remembering, the regulator i showed earlier with the mount hole in the middle its just a small diecast alloy box with no fins at all, and if they can handle 200 watts, then if i build something maybe a little bigger, maybe with some fins, attached to the bike frame and in a location that gets air flow and the internal components can handle it, then i see there is nothing stopping me making one that can handle 250 watts. And if i can that means no need for riding during the day with headlights on and using an under rated regulator, which equals longer bulb life.
Another reason i would like to make my own, is that i can fine tune the regulated voltage a little higher than the readily available regulators. I could aim for around 14 volts. This produces bright burning globes. A lot of aftermarket general use regulators regulate from around 12.5 -13.8 volts depending on brand and who makes them.

here some current figures for some examples

all based at nominal 12 volts

50 W - 4.16 amps
75 W - 6.25 amps
100 W - 8.33 amps
150 W - 12.50 amps
200 W - 16.66 amps
225 W - 18.75 amps
250 W - 20.83 amps

if the voltage is upped slightly then the current will be a little less. In Suzukimans situation i believe his Hondas that he wants to put regulators on have a stock output of around 60-80 watts i reckon which is about 6-8 amps roughly so if he built he built his to handle 100 watts that would be plenty, he could run the bike with the lights off in the day and not have to worry about having to leave the lights on to protect the regulator and 100 watts is perhaps a little higher than he needs but there is a good feeling of knowing its a little over rated and the regulator will be well protected and will handle shunting the 100watts when not in use.

I will get stuck into disceting this other regulator tomorrow as i was out today. just got a bit more potting mix to remove to reveal the components.