Modern Vespa

looking for help understanding the electric system a bit more. I am converting my system to a 12v AC/DC with battery system.

I have some dumb ass questions - that I know have been addressed in one form or another, but I am still wrapping my brain around this electrical set up.

I know I can go batteryless, but in my opinion, a battery would be better, and I am stoked about having a 12 v system.

1. The Rally (74 femsa) Stator normally puts out 6 v (or thereabouts)
AC? is that correct?

2. By re-wiring the coil outputs or changing the lighting coils, you change the output to 12 v AC --- the two techniques I have read work ..

is one way superior to the other or are both methods creating the same full wave DC ( I am not even sure what full vs. half wave DC is)

3. The 12 v AC goes to the regulator/rectifier, and from there you can hook up a 12 DC system with a battery. I get these concepts.

4. You can keep your horn AC or run a DC wire to a DC horn off of the battery, or accessories etc. Keeping it AC pulls less juice off of the system.

00000000000000000000

also, I have read about xenon lighting. Is this legal?

any of you that take the time to help me. I thank you kindly in advance.

Here's what I know after dealing with my Rallys

1. Yes the double yellow wire Rally stators normally puts out 6 V AC

2. Yes you can change the output to 12V AC. Barry Gwin at SF Scooter Centre told me to ground out one of the yellow wires and then use the other yellow as your hot wire to your reg/ rec. I tried his way and it worked, so I have been lazy and havent looked into any other options.

3. Yep sounds good. You can pick up aftermarket 12V regulator/ rectifiers for pretty cheap

4. US 74 Rallys had a DC horn on them. One of the sad things when you go batteryless is you lose that horn option

You can read into it a bit but a while back I was trying to use bridge rectifiers on a batteryless Rally to convert just the horn circuit to DC and enable the horn. I never could get enough amperage to make the horn beep. The revving engine was much louder than the horn. I'm still trying to get it to work.

5. I've only tried halogens but I have a Xenon 12V bulb from Scooterwest that I need to open. Make sure the base is the same whatever you do decide on. The halogens work well for the same wattage as the old bulbs. I didn't know Xenon bulbs were illegal?

Just for my own curiosity how are you wiring up the bike? What circuits will be AC vs DC?

I am planning to have a 12 v battery in the DC circuit, because that will work as a capacitor and smooth out voltage draw at different revs.

The main thing I need to change is to get 12 v AC from the stator... so thank you for that confirmation.

I had thought about doing non-battery, but as long as I don't have to deal with the crappy 6v batteries, I will likely not dislike the battery set up.

I have scoped out some super ballistic lithium batteries that won't discharge constantly, which is the main thing that made me hate the 6 v system. That and the bigger variety of horn and light options that 12 v opens up.

I wonder why 1 yellow wire gives 12 v ac and 2 yellow wires gives you 6v... do you understand the physics of this?

4 Rally 200s, that is dedication. I love this model. It is one of the most fun to ride.

thanks

I get 11.85v. Or about that, on 5 different Rallys I've patched up to go 12v. Run it through a 12v regulator. Very nice increase in brightness - and it is noticeable.

I stole this from Scooterrescue.com

12 volt conversion by simple wiring change. - The Rooster
You ground one of the yellow wires on the battery side and connect the other yellow wire to the old battery (+) wire and the green wire. There may be some variation to this, but the same (or similar) conversion works on A LOT of bikes. My wife's Rally 200 ('78) and a clubmates Rally200 ('73) are wired this way and work GREAT with a universal 12v regulator.There may be some trial and error, but the end result is good and you don't have to buy anything but a regulator and you DO NOT HAVE to remove the flywheel or rewire the stator. You could probably figure out turn signals with an AC flasher and a bit more experimentation.I cannot take credit for this, it was handed down/taught to me by some friends.

If you ever need help going batteryless ask SFvsr. Dude knows his shit and taught me a lot

How to get 12V from a twin 6V stator? Put the two coils in series: 6V + 6V = 12V. Just like putting two batteries in series (in series means hooking the + from one to the minus of the other).

Each of the yellow wires comes from one end of two different 6V coils. The other end of each coil has a white wire. So, from white to yellow you should have ~6V AC. To get 12V, most people ground a yellow, connect the whites and the remaining yellow is ~12VAC. For some reason, Piaggio regulators/rectifiers took both the white and yellow into the box to convert to DC. Modern systems usually just ground one end of the coil and then use the other end of the coil as the +AC.

For both AC and DC, has anyone tried one of these? Can this provide enough DC current/amps to power the horn?

http://medias.scooter-center.com/bgm-regulator.pdf

It doesn't say anything about wattage capacity, so it would depend on the total watts used by your lights, etc. right?

I have seen some regulators that are geared up for higher wattages.

so it depends on your total need.

btw, thanks for the efforts to shed the light.

My hope is to run everything on the AC side (headlight and tail/brake light), which the regulator only has to, well, regulate. The only thing I want to run DC is the horn so I am hoping the rectifier side can put out enough for the horn. I will keep everyone posted!

Love the pun!

no. this is not how current sources like these coils work. i naddition, you run into other problems like phasing of the AC.

Rob, you have me curious, please explain!

if i get a chance in the next week or so i will, but it's way late and i' m woking like a dog these days. wife's already come out of the bedroom leering at me t get of the computer twice tonight so i gotta go.

With the way I do it you run everything off the stator. Everything works: tail light, brake light, headlight, horn. Everything.

The stator coils are only 6v when a certain current draw is applied and each are capable of providing 12v on there own (if loaded correctly).
Using 1 yellow to earth and the other to the reg will have the coils in the correct phase and will give a higher unloaded voltage but isn't the best way of getting more power out of them. A better way of doing it would be to put them in parallel and this is exactly how Lucas did it in the 60's with the Lambretta 12v DC system, the original "6v" coils in parallel with another pair. May have mis-interpreted you (apologies if so) but the reg wattage rating has no bearing on what loads you are running so using a higher rated reg will not give you more power for lights. Load current doesn't go through a shunt reg at all, only waste current passes through it and this is where the rating is relevant.

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Alright. So, does switching the lighting coils out for the Indian ones, (the other 12v conversion mode that is talked about) create this parallel arrangement, and thus would be more powerful (thus better) than the grounding the wire technique? Or does the lighting coil change simply accomplish the same thing as the grounding wire.

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Also, what is the benefit of purchasing a higher rated regulator. What does that extra wattage rating provide?

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Hey SF - I thought I have read that DC horns only work on DC? Have you found an AC horn or does the DC horn work on AC or are you rectifying to DC?

Fire - Yes the coils do create more than the 6V, and putting in parallel will create more current (as compared to in series which increases the voltage), but assuming the coils each produce enough current, what is the voltage at idle of the single coil or dual in parallel?

It is good to know that they are phased closely enough to increase the output, it would be funny if they were 180 degrees out of phase and cancelled!

Craig - The 12V coils are wound differently to produce the higher voltage. A coils output is dependant on the number of turns, strength of magnetic field and how quickly they pass each other. The wattage rating of a regulator is how much power can be drawn from it.

Rob - Let us know when you get some time for the computer (and be glad your wife wants you to come to bed!!)

Yes

If you have the 74 stator with two yellow wires and two white wires proceed as follows: Float 1 yellow (doesn't attach to anything) and ground the other yellow. Combine the two white into one lead into your regulator/rectifier. That will give you your 12 volts. The DC will be 1/2 wave though, but if you run it to a battery it will keep the battery charged, and you can use the full wave from the battery for the horn, turn signals, garmin power etc. On mine I use the resulting 12 volt AC for the lights and horn (scoot came with an AC horn) and the SIP speedo/rev counter. I lengthened the stator wires and do the connecting/floating at the junction box on top of the case-makes it easy to swap connections around.

So, instead of the wire swap, what type of wave AC does one get from exchanging the lighting coils for the Baj Indian Coils, as is posted as a way to get 12v AC. Is that full or half wave? And would that likely be more powerful?

Classic Rider - please explain because that just doesn't make sense to me. BTW - doesn't mean it isn't correct, just doesn't make sense to me!

"Floating" one yellow leaves one coil not being used as you are only connecting to the white of that coil, it can't do anything?

Grounding the yellow of the other coil will give you power on the white wire coming from the other side of that same coil...But it is only power from one coil, designed in the original system to provide a good 6V and above from idle on up...They do produce a lot more than 6V when revving, though...

Headlight is powered by the AC and what size bulb? Does it dim at idle?

When I was researching converting from 6v to 12v last year for the Cannonball I wound up getting into a lot of stuff that was over my head as to "why" it worked, but one of the things that kept coming up was to float one of the coils. I experimented with them in series and parallel, floated and unfloated, and the set up I described worked best as far as useful power is concerned. In series the voltage would go way high, but there was no current/amps to go with it. As it is, I have a 35 watt halogen bulb (I think that's what it is) that is bright at idle. From what I understood from my researching our coils aren't limited to a particular voltage per say, but on the basic systems like the VBBs etc. the load on the system (bulbs) would regulate the voltage. The other thing I discovered was we are basically limited to single phase AC due to the space on the stator where 3 phase would really be nice. Perhaps the biggest single thing I'm happy with is bringing all the coil leads up to the junction box on top of the case, it makes mixing and matching coil/ground/float combinations so much easier than pulling the flywheel to get access to the stator plate. I opted for the AC/DC to have charging power for a Garmin unit, and DC turn signal flashers are much easier and cheaper to find than AC ones. I would have stayed AC only if I didn't need the DC.

Classic

So which regulator did you buy/use for your 12 v AC/DC system?

And which Battery did you use?

Thanks for the information.

Craig

That's George Harrison. He was a Beatle.

but AC/DC?


1:18 in he forgets the words. lol

Craig, OK. But first could you do something about this, please?


how the hell am I supposed to read that?

Hey Classic, Thanks for all the info!

I have a bike almost ready to assemble (hence all this curiosity) and look forward to testing similar to what you did. I had to rewire a tired stator and have also brought all the wires up to the junction box like Piaggio.

One last, what regulator/rectifier did you use?

here is another from The Oatmeal. For more, see the oatmeal.com

thanks for the electrical help.

Firstly, I know naff all about the Indian coils so can't comment on them.
As I said earlier, and as Classic Rider has proved, these coils are quite capable of producing 12V. They are only 6v when the correct load is applied across them and of course the regs function is to keep this load constant no matter what consumables are switched on. Although in phase for series connection they will be out of phase for parallel. Wired correctly in parallel you will not increase the voltage (you don't need to) but double the current output which equals double the power.
Re the earth, this has nothing to do with power output, whether you earth or not will depend whether you want AC/half wave DC or full DC.
If you have a high output stator the reg is going to work harder when you are NOT using that power, so you need a higher rated reg to cope with this.
If you are using all available stator power, the reg will not have to do anything.

For the regulator I first went with the one from the scooter parts store that can't be named http://tinyurl.com/3cpzgay but wasn't happy with the DC output, so connected the AC output from it to a BGM 4 plug http://tinyurl.com/jw7guu2. I could probably just use the BGM but was too lazy to swap the leads and mounting. Both are mounted on the left side by the spare tire.

I suspect any regulator/rectifier could be used. If you get one that has the charging "sensing" circuit that might be able to be ignored. You just need to make sure the DC out voltage isn't too high or it could over charge the battery (the problem I had with the first regulator I used)

The battery is a Motobat MB3U. It fits in the battery compartment, but needs a spacer at the bottom since it's shorter than the 6V battery was.

I was looking at the Motobatt you mentioned. It looks too wide for the battery compartment on a Rally

did you mean a different one?

thanks

sorry my bad. Picture was blown up.

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thanks

That was the best fit I could find in a 12 volt battery without rebuilding the battery box. It might even be enough for a DC only system. Another thing to consider would be a capacitor system used on some motorcycles. Here's what the installation looks like (sorry about the road dirt-it's been over 6500 miles since I installed it)

THANKS! picture helped a lot.

any concern about the lower amperage rating?

also, where did you get the holder set-up?

No concerns on the battery amps. I only use the DC for the turn signals and occasionally a Garmin. Neither use requires much power and the battery is being charged while the engine is running.

The battery bracket is DIY with aluminum from the hardware store.

I am back working on this. I tried the advice from classic rider of grounding one yellow, floating the other, and attaching the white wires to the new regulator, but was not getting any juice.

My current battery is dead, and I am awaiting a new one. But I should have been reading 12 v AC from the white wire if this is going to work, and I was not.

On my original rectifier/regulator, the pattern was (yellow, yellow, AC IN then a white/red jumped connected, then marroon with the green&white - this was the DC out.)

questions #1 was the purpose of the white wire was attached to a jump connection simply to ground it? The connection to the regulator is merely to the box and it then also runs to a small red wire that ran to connect up with the DC battery circuit. So, AC to DC makes no sense, but grounding does.

See Diagram attached

So, I am thinking I need to use a yellow wire for the AC IN - and leave this white one attached to ground?

What I am trying to do is set up the system to run on 12 v DC for the lights etc. Which would seem to be simple
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From the Stator, I have 2 yellow wires and one white wire that make their way over to the battery side.

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also, for Classic Rider

I would love a close-up shot of your regulator as I thought I saw two yellow wires going in

and, I am wondering about the red wire going to your negative battery side?

Thanks.

I need to REALLY read this thread but maybe there's something in my earlier post that could help you somewhere, as my GTR set-up is similar I think to the Rally..

How do I do a 12v electronic ignition conversion?