regulator size

[jonnyr48]

soooooo.....er, re-winding with less coils? or thinner wire? whats the difference between a 24v alternator and a 12v? (excuse my ignorance everybody, i never listened at school! now i pay the price).

[tappy]

Yep - assuming the same strength of magnetic field (flux), more voltage is achieved more more turns of wire.
For an alternator of a given size however this will require thinner wire, so the alternator's internal resistance will be higher, and the amount of current it can deliver will be lower.
So in this case the higher voltage alternator needs to be re-wound (or just buy a new stator) with fewer turns of thicker wire. Revs will be lower, current capability will be higher, total power capability will be about the same.

Which brings me to an idea I had:

When the current comes out of the alternator - before it gets to the rectifier - it's alternating current (AC).
SO, you could actually use a simple coil transformer to halve the voltage and double the current. Such devices are much cheaper and far more reliable than DC-DC converters, which is why our national grid was set up that way.

Transformers are typically designed to work at a particular frequency to keep their size down and efficiency up. Given that the frequency of the AC current varies with engine revs this might mean you'd end up with a fairly bulky, lossy transformer. Worth a look though.

[jonnyr48]

hmmm, the transformer idea sounds a little tricky....the alternator wire is currently about 1.0mm,what thickness would you recommend?

[jonnyr48]

as a thought, does anybody who is using the lombardini 850 twin (or ruggerini come to that) know how many windings and/or what diameter the copper wire is in their flywheel alternator? or non-flywheel alternator, it must be fairly close?

[mark_in_manchester]

If I were looking to see if a 2:1 transformer would do what I needed to do, I'd reach for a 240v-110v job for running US gear on a UK supply. But that's probably just because I happen to have one floating about! They do come in all sizes though, and ebay might be your friend - I'd say it was worth a try.

[jonnyr48]

yeees, but...i have no idea what i would be looking for or how to wire it! i can rewind the stator easily enough, but its knowing which thickness of wire and number of turns to go for.. hopefully somebody on here can give me some idea.i think quite a few people have this (or very similar) engine. thanks for all the ideas tho!

[tappy]

I have the flywheel alternator rotor and stator from a Hatz 2G40 - virtually the same engine as the Lombardini & Ruggerini 950, and I expect identical alternators too.
Mine is 12V. It has 10 poles, each wound with copper wire approx 1mm diameter. Not sure how many turns as without unwinding it it's hard to see how many layers there are. I'd say about 12 turns per layer, and 1.5 or 2.5 layers.
They're cross wound so the turns go down the outside of one pole and back up the next.
If you give me a nudge at the weekend I'll try and take some decent pictures.

[jonnyr48]

thanks tappy, sounds similar to what i have but there are 3 layers on mine, which would make sense. any pics or clues about the layers would be brill ta mate

[tappy]

It may well be that both 12 and 24V windings use the same number of turns of the same gauge wire (keeps the set up the same).
What will change is the connections between the windings on each pole - with the 12V version having more coils in parallel, and the 24V version having more in series.

[jonnyr48]

thanks tappy, i'll try to figure that out! will you have a chance to take pics this weekend?

[jonnyr48]

hi tappy, i have 10 poles,the windings are one continuous wire going around 5 poles, and another going around the other 5,only 2 wires in total, i am presuming this is in series like you say (impressively ignorant,no?).so what i need is 10 wires, one for each pole?

[tappy]

Hi Jonny, sorry for the slow response - it was perhaps naive of me to hope that my last weekend and work days before Christmas would have some free time...

I've taken some pictures, but think a diagram is needed also.

Similar to yours, my alternator also appears to be wound with two wires thus:
Wire A goes into a pole 1, winds up and back down it, then jumps around the back of pole 2, and goes into pole 3. It carries on like this and covers Poles 1, 3, 5, 7 & 9.
Wire B jumps around the back of Pole 1, goes into pole 2, winds up and back down it, then jumps around the back of pole 3, so covers poles 2, 4, 6, 8 & 10.

I have a suspicion yours does this also?

The key difference is how these two wires are joined at their ends.

I can't tell without unpicking my windings, but I'd imagine that on my 12V alternator:
Wire A "start" and Wire B "start" are joined together. Wire A "end" and wire B "end" are joined together.
Where these joints are is where you extract the AC voltage and send it off to the reg/rec.

What I'd expect for the 24V alternator is:
Wire A "start" goes to the reg/rec connector.
Wire A "end" connects to wire B "start".
Wire B "end" goes to the reg/rec connector.

I'll draw a diagram later.

In the mean time, if you could take any pictures of your windings or also do a diagram of how your windings are connected that would be good. With a bit of luck you won't need to un-wind and rewind anything, hopefully you'll just be able to change how the 2 wires are connected together.

[tappy]

Hi Jonny,
here's a picture of the windings on my alternator and a couple of diagrams that show how the 12V and 24V versions *might* be wound.

[jonnyr48]

thanks tappy, i think mines different to both the above,but im crap at computers as well as electrics! so ill have to wait until mi chica comes back on sunday to ask how to put a diagram up.ill see if she knows how to do photos too.if i remember right the 2 ends of the wires from one set of 5 poles are joined together to the incoming wire (to the regulator) and the 2 ends from the other set of 5 poles are joined together to the outgoing wire(to the reg.). hope this makes some sort of sense to you. ill have to take the alternator off to look (the bikes a bit buried at the mo, and im trying to get a roof put on a little house im putting up!). happy new year anyway, to you and all the other people on here who are so generous to give up time to help! thankyou all

[gilburton]

Well these diagrams are exactly the same apart from the wire that "bridges" across between the coils just below the 2 output wires.This gives you the 24v in series.
As far as I can see you would just have to locate the "bridge" and cut it and then join the cut wires to the 2 output wires to give you 12v in parallel??
This link is not where the name suggests but if you could find somewhere similar in your area they might be able to modify it for you??


http://www.westcountrywindings.co.uk/

[tappy]

Well these diagrams are exactly the same apart from the wire that "bridges" across between the coils just below the 2 output wires.This gives you the 24v in series.
As far as I can see you would just have to locate the "bridge" and cut it and then join the cut wires to the 2 output wires to give you 12v in parallel??

That was indeed my point. Sadly, I can't see Jonny's current windings so I can't tell him if they match what I suspect.
I've used WestCountryWindings myself some years ago - they were based in Dorset at the time

[jonnyr48]

hi guys,having uncovered the beast to check the windings i find that you are, of course, correct tappy! i shall try just changing the ends of the wires to sort it out.thanks very much for all your help, i¨ll let you know how it turns out. cheers, jonny

[tappy]

Ha ha - there was no "of course" about it - just an educated guess. Delighted to get a good answer though
Make sure you join "start A" to "start B" and "end A" to "end N". If you join "start A" to "End A" and "Start B" to "End B" then you'll get zero volts out but possibly some very high currents and a melted alternator...

Keep us posted tho

[jonnyr48]

hi tappy, having finally got around to rewiring it,and rereading your "dont melt it!" advice, ive realised that my wiring is subtly different to your diagram possibly? take a gander at my impressively childish drawing and let me know what you think??
cheers, jonny

[tappy]

Ummmm, you may or may not have a problem - it's impossible to say from the diagram.

Your left hand blue wire meets the red wire going clockwise and the black wire going anti-clockwise.
Your right hand blue wire meets the black wire going anti-clockwise, but meets the red wire going clock wise.

If both the red and black wires are wound up the poles in the same direction (looking down one of the poles the coils always all wind clockwise or all wind anti-clockwise) then basically one wire will be producing +12V when the other is producing -12V.
In this case you'll possibly melt the stator and won't get anything out of it. To sort this you need to cut both ends of the red wire where it meets the blue wires, and reconnect them to opposite blue wires. Now both will make +12V.

If the red and black wires are wound up their poles in opposite directions (looking down one of the poles the red coils all wind clockwise and the black all wind anti-clockwise) then you'll be OK anyway.

If you've wound various different coils in different directions then you'll have less output and might damage the alternator, but it seems unlikely that you'd do this.

It's a bit late, so I'll think more tomorrow and do you a couple of pics.

[tappy]

Have a look at the picture attached. The top version is correct. Both the two lower ones are incorrect and will result in no output.
I have a suspicion you've done the bottom one, in which case swap the ends of just the red wire, or just the black wire, but not both.

Hope this helps,
Taps.

[jonnyr48]

weeellll, errr, it doesnt seem to be any of these....the confusing thing is that it was putting out juice - 13 volts at tickover according to the guy who measured it...? the windings ALL turn anticlockwise (looking down on the poles). what happens to the end of the red wire in the top 1 of the 3 versions in your diag.? it just ends without being attached to anything? i dont quite get that.... cheers jonny

[jonnyr48]

weeellll, errr, it doesnt seem to be any of these....the confusing thing is that it was putting out juice - 13 volts at tickover according to the guy who measured it...? the windings ALL turn anticlockwise (looking down on the poles). what happens to the end of the red wire in the top 1 of the 3 versions in your diag.? it just ends without being attached to anything? i dont quite get that.... cheers jonny

[tappy]

Yeah sorry - I didn't draw the whole diagram. In all the versions, the other ends of the black and red go to the other blue wire...
Without a regulator on it I'd expect it to be putting out a bit more than 13V at tickover. If that was measured with the regulator in place, then I'd want to do a few other tests without the regulator first.
Such as - measure the unloaded, unregulated voltage at 3000rpm. I'd expect anywhere between 60 and 90V AC.

[tappy]

Of course I might be wrong. If it's all behaving itself then great. If not, then it could just not give much output, *could* kill the reg-rec, or it could just melt itself.
You've already re-wound it once quite happily so perhaps the last of these 3 isn't that much of a problem

[jonnyr48]

the 13 volts was with the regulator in place, but it wasnt actually charging the battery - hence im assuming the regulator (VERY old, off a different ruggerini) was buggered. the new one cost me a small fortune, so im not desparate to experiment seeing if itll get wrecked... rewinding was satisfying and not a load of money actually. i thought running the alternator without the regulator attached would burn out the stator? sorry but i also dont get which black and which blue wires you mean on your diag. - the black turns into a blue on my wrecked old laptop - is that how its meant to look?
cheers jonny

[jonnyr48]

you see tappy, im thinking the alternator must(?) be 24 volt as ALL the other electrical parts were on the engine, cos it came from the military. so it presumably sent a whacking great charge to the regulator which killed it - if you're sure the top diag. is the correct one for 12 volt then i'll just change the ends of 1 winding as you suggested?
cheers, jonny

[tappy]

Oooops - my bad, I hadn't noticed that I'd left some of the "windings" the wrong colour on the diagram!
Note revised diagram attached - it's the same colours as in your diagram and is more complete so hopefully a bit clearer!
I've left off the "3rd version" as it sounds like you've wound all the poles in the same direction anyway.

Now then - I think the version you've got is the bottom one, and the one you need is the top one.

The bottom one *could* be correct depending on the arrangement of the magnets, but the fact I predicted how the 24V one was wound makes me think the top one's right.

I can well imagine you don't want to ruin an expensive regulator. For future reference I suspect the single phase Harley ones available fairly cheap from ElectrexWorld are perfectly up to the job and rather simpler to wire in.

You can do a few tests with the regulator not fitted - mainly testing the unloaded voltage, then wiring in a few 12V headlight bulbs in series and measuring things agaon. These tests will tell you what voltage is coming out and what power can come out. If those are OK but the reg/rec output isn't, then the problem is the reg/rec.

[tappy]

Oooops - my bad, I hadn't noticed that I'd left some of the "windings" the wrong colour on the diagram!
Note revised diagram attached - it's the same colours as in your diagram and is more complete so hopefully a bit clearer!
I've left off the "3rd version" as it sounds like you've wound all the poles in the same direction anyway.

Now then - I think the version you've got is the bottom one, and the one you need is the top one.

The bottom one *could* be correct depending on the arrangement of the magnets, but the fact I predicted how the 24V one was wound makes me think the top one's right.

I can well imagine you don't want to ruin an expensive regulator. For future reference I suspect the single phase Harley ones available fairly cheap from ElectrexWorld are perfectly up to the job and rather simpler to wire in.

You can do a few tests with the regulator not fitted - mainly testing the unloaded voltage, then wiring in a few 12V headlight bulbs in series and measuring things agaon. These tests will tell you what voltage is coming out and what power can come out. If those are OK but the reg/rec output isn't, then the problem is the reg/rec.

[jonnyr48]

thanks tappy - so in the top diag. the red wire goes straight on to join the blue wire and both join the wire to/from the regulator? by the way, the magnets are embedded in the metal plate that spins around the stator, theyre square,about 3/4" wide, and (if my memory serves me correctly?!) the gaps between are a similar size. the alternator has to always be connected to the battery surely, even if not the regulator? (temporarily); for measuting the unloaded voltage, i mean.
cheers, jonny