Author Topic: 12 Volt Vs 6 Volt Generator  (Read 4810 times)

Offline trevinoz

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12 Volt Vs 6 Volt Generator
« on: 07.04. 2009 07:13 »
I recently rewound an E3L generator to 12 volt specs just to see the difference.
The armature has more turns of wire at 0.7mm compared to 0.8mm.
The field coil has 50% more turns at 0.6mm compared to 0.7mm.
At the moment I don't know what speed I tested it at as I don't have a tachometer but hope to borrow one in the future.
The data is as follows :- Open circuit voltage -  23V
                                 Regulated open circuit voltage - 13.7V

I connected a 12V 60/55W Halogen headlight to the regulator and got the following results:-
                                 55W filament - 13.8V
                                  60W filament - 13.6V
                               60 & 55W filaments - 8.4V
I then repeated the experiment with a 6Volt generator which I had rewound and found the following:-

                                   Open circuit voltage - 13V
                                  Regulated open circuit voltage - 12.75V
                                   55W filament - 9.7V
                                   60W filament - 9.4V
                              60 & 55W filaments - 7.1V

From this it can be seen that the 6V generator needs to be run a lot faster to be in any way effective as at my test speed the voltage didn't reach the regulator set point and the high wattage lamps loaded the generator excessively, would probably be OK with a lower wattage lamp.

The 12V rewind seems to be the way to go for anyone using their bikes at night as a decent Halogen lamp can be used.
By the way, this generator is yet to be tested on a bike, all the above was done on the bench.
  Trev.
                                   
 

Offline groily

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Re: 12 Volt Vs 6 Volt Generator
« Reply #1 on: 07.04. 2009 08:39 »
That is fascinating data Trev.
I've been playing a lot with dynamos and regulators recently (largely inspired by the ability to do so conferred by Manormike's oh-so-excellent DVR2 regulators) and have come to broadly the same conclusions.
The theoretical max to be derived from one of these generators, without increasing the internal heat generated in the field, is close to 140 watts; but only at the cost of not-useful compromise. To get that, it takes a fine-wound field coil ('12v' in the vernacular) with a thick-wound (ie '6v' as per original), armature winding. To get the thing to cut-in point takes a handful of rpm - close to 2000 - and it won't be regulating properly until closer to 3000 rpm. Ergo not a lot of use in normal riding. And the output is theoretical - I haven't tried to measure it, as it's a noisy business holding throttles at 3000rpm plus in the shed.
However, the use of an original thick-wound armature and original field at '12v' does give around 80 watts reliably, at the cost of some heat having to be dissipated in the field after Cut-in rpm and before full regulation kicks in. This would load the field a lot on long-lkegged machines habitually driven between those rpm, especially in built-up areas. In fact, the internal load at those rpm can be more than the dynamo is rated to cope with, although they seem to work OK - I have been running one machine in that configuration for over 20 years with various regulators of the early electronic type, but now a DVR. No melt-downs despite the absence of current regulation, as in all these applications - fingers crossed for the next 20 years.
 
I have one original 6v set-up (on my A10) which is OK and supports a 35W halogen just fine as you'd expect.
And I have one machine in this experimental hybrid 'fine field thick armature' mode, which may be OK for the summer for a country boy who seldom rides in heavy traffic, but I'll have to swap the field coil back to original or get a fine-wound armature for the autumn, to get reasonable cut-in and regulation rpm. These dynamos also run with DVR2s.
My only whinge with the fine-wound fine-wound mix is that you are stuck with 60W nominal output obviously (but the big plus is you retain the original cut-in rpm). But it would support a 45/40W halogen OK as long as the magneto is retained of course.

All depends how badly we want lights for what we do. I unfortunately need them often, to the point that I regularly take something with an Alternator when in doubt.

I was interested a few weeks ago, talking to Gary at SRM when ordering up a fine-wound filed coil for the hybrid experiment, to learn they they are looking at ways of getting more out of the original E3L generators, presumably because they are finding people overload the '12v' 60 Watt set-up. They apparently want to try to find some extra oomph, but it's hard. I think I heard him say that they are also going to be, or are, stocking DVR2s - but not sure about that. I for one never cease to extol their merits - to the point of boring people to death. And that's having had mechanical regs, JG ones, Podtronics ones, you name it. The DVR2 is the best I've had yet.
Bill

Offline RichardL

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Re: 12 Volt Vs 6 Volt Generator
« Reply #2 on: 07.04. 2009 18:39 »
With only the most miniscule fraction of Groily's experience, I, too, extol the DVR2.

Richard L.
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Re: 12 Volt Vs 6 Volt Generator
« Reply #3 on: 07.04. 2009 18:52 »
I to use Mikes regulaters on both of my A10's owerthe Super rocket has one of Shaun Hawkers belt drive kits which drive the dynamo at a faster speed I have a 23w side light fitted for daytime running if required and a 45/55w halegeon headlamp bulb and a led rear lamp, I supported this with a 9ampere battery and have had exellent results
Let me know how you did your volage test and I will try and test my S/R the same and report the values.
The old Flash still has the chain drive and on slower engine speeds there is a difference
Richard

Offline Dynamo Regulators Mike

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Re: 12 Volt Vs 6 Volt Generator
« Reply #4 on: 09.04. 2009 15:41 »
Thanks for the kind words about the DVR2 regulator chaps. You?re making me blush. *red*

Interesting thread this is shaping to be. Shame about the lack of speed data Trev. Due to the characteristics of filament lamps power is not proportional to the applied Voltage squared. A rule of thumb may be applied that power in a given lamp is actually proportional to v raised to the power 1.6. Also note that many if not most auto bulbs are rated at 13 V.

Ignoring the details of the maths  *conf* this suggests that your 115 W nominal load (at 13 V) drops to 43 W at 7 V, i.e. just over 6 Amps. On my test rig I measured about 7 Amps at 7V for a 60/55W headlight bulb, so the approximation seems not far out.

The point is that a standard E3L dynamo should be very happy at this loading. Lucas spec gives 8.5 Amps at a very modest 1,850 to 2,000 rpm dynamo (not crank) speed. A true load of 115 W on an E3L at 7 V would likely result in a pretty rapid meltdown. But it can happily run a 60 W headlight (halogen or not) at 12 V, with its standard 6V windings and a DVR2, without excessive speed, and indeed electronic ignition as well.

Do you know the resistances of the field winding used  in you tests, Groily and Trev? A few more truns on both field and armature would seem to be better for a 12 V conversion, but data on the available variant windings does not seem to exist.

There is no getting away from a dynamo?s output being proportional to its speed, and the number of turns in the magnetic field. Practical limitations to output include mechanical strength of the armature, winding and brush resistance (heat dissipation), and magnetic saturation field strength. Maybe SRM can come up with something radical, using modern steels, smaller air gaps, efficient cooling, rare earth magnets or whatever. Meanwhile they are indeed now stocking  the DVR2.

Cheers
Mike
Mike Hutchings
A10, B50, T800; 1,2,3 (& DVR2)
Director, DRL www.dynamoregulators.com

Offline snowbeard

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Re: 12 Volt Vs 6 Volt Generator
« Reply #5 on: 09.04. 2009 17:46 »
ok, I am barely following this conversation, so please speak slowly...  ;)

I still have the all original setup, E3L, 6V battery, mechanical regulator (that apparently still works!) and whatever bulb was in the headlamp when I got it (it lit up so I didn't mess with it much) 

I have obviously variable lighting with rpms, it drops to very low when stopped at a light, and I can see it brighten when I rev the engine.  I have nominal light for riding at actual riding speeds, it works for town but a dark night on a long road I can only imagine will be terrifying.

with the money I'm putting into my head, I hope to do some distance rides, theoretically still in the daylight, but we all know how well theory holds. 

what sort of things can I do to help out my headlamp for night riding?  maybe a better 6V bulb?  better gel battery?  I currently have the 6N11A1B for a battery.

can your DVR2 reg pull more out of this original system Mike?

sorry to be slow, but my first thoughts were simply to get 'er running, now I'm hooked and might as well make 'er reliable too!
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Offline beezalex

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Re: 12 Volt Vs 6 Volt Generator
« Reply #6 on: 09.04. 2009 18:29 »
I guess it all depends on how good your eyes are, but the 6V lighting on my flash is adequate with the DVR2 (Add my name to the list of people recommending it) and a standard lucas bulb.  I must also say that I find the lighting much better on a dark road than in town because your eyes don't adjust well to low light levels when there are a lot of other cars and ambient light.  That said, when I ride my Royal Star with 12V 55/60W halogen lighting, it's absolutely stunning how well my path is lit, so it all becomes relative I guess.

BTW, if your lights get dim at idle after riding for a while, you battery's bad. 
Alex

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Offline snowbeard

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Re: 12 Volt Vs 6 Volt Generator
« Reply #7 on: 09.04. 2009 18:46 »
ah, I suspected as much. I had the seat off and noticed some corrosion around the terminal, so I cleaned all that up and checked the water/acid levels. they were very low, so I topped up with some fresh acid.  I may need to just step it up and buy a new battery, eh? it's only a year or so old tho.

 I'll see what it holds now with new fluid, I have a tender that I was using also, which did appear to give it full charge and go green after a night. 

so does the DVR2 do more than a working mechanical? or is it just a more reliable modern replacement when the mechanical goes south?
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Offline beezalex

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Re: 12 Volt Vs 6 Volt Generator
« Reply #8 on: 09.04. 2009 19:00 »
I'm going to guess that if you battery was cooked out, you regulator isn't regulating very well.  You should definitely check to see if the voltage output is going above 7.5 volts.  If it is, that's going to be rough on the battery.

The DVR2 offers better regulation than the original, mostly because there are a lot of tradeoffs that are made in the mechanical regulator that constitute losses.  The DVR2 also has no moving parts to wear out because it is fully solid-state and if you, at some point change your mind, it's easy to reconfigure for 12V.  On top of that, I found that with the current exchange rate, it's cheaper than the podtronics or a new mechanical regulator.
Alex

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Offline snowbeard

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Re: 12 Volt Vs 6 Volt Generator
« Reply #9 on: 09.04. 2009 19:10 »
hmmm. it could be that the mech isn't working now, but it was when I got the bike up and running at first. haven't checked for a while, I'll look into that as soon as I get her back together...  one more thing.*conf*

thanks Alex!  *smile*

Hey Mike, can I order your DVR2 direct? or should I just go thru a supplier?  maybe I should just get two since I need one for the super rocket basket as well, maybe I need one for my Royal Enfield Hornet 250 as well!!  yikes!
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Offline beezalex

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Re: 12 Volt Vs 6 Volt Generator
« Reply #10 on: 09.04. 2009 19:23 »
I'll do the advertising bit for you, Mike, if you can enlighten us on that other thread about the current regulating characteristics of the DCR2, cause I gotta be honest, I don't know about that particular one.

Snowbeard, here's the web addy:
http://www.manortec.co.uk/dvr.htm

I got mine in about a week.  Great service and a solid article at a reasonable price. *beer*
Alex

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Online olev

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Re: 12 Volt Vs 6 Volt Generator
« Reply #11 on: 09.04. 2009 22:58 »
Thanks Trev & Groily, Thats the best write up on on these generators I've come across. It will be interesting to hear what happens when Trevor sticks his generator on a bike and takes it for a decent thrash at night.
Is the alton an alternative? Are they reliable?
The ability to drive a quality electronic ignition (if there is such a thing) with a good headlight sounds attractive to me.
Happy Easter everyone, cheers

Offline groily

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Re: 12 Volt Vs 6 Volt Generator
« Reply #12 on: 09.04. 2009 23:15 »
Don't know the resistance across my fine-wound field coil Mike as I didn't measure it. Sorry. A small handful of ohms I assume.
It was what SRM supplied, while I was in daft 'play' mode, trying to see what the effect of having a fine field and coarse armature would be in practice (and trying to reduce field load after cut-in and before full regulation). Result, unhappiness for fairly predictable reasons - but the ammeter suggests it produces some useful and very sustainable oomph at high rpm. I think the ideal would be a fast-turning dynamo with a field coil with something more than the windings of the '6v' standard one, but fewer then the '12v' coils available from SRM, Feked etc, with a standard wound armature. But it all depends what conditions we ride in, eh? In the sticks, where revs are available, no problem; in town, another story, as the old cut-in issue rears its head. And on whether the mechanical side of an E3L can handle it too, as you say elsewhere. I expect I'll melt something soon, but it's interesting in the meantime.
Glad to hear that SRM are indeed stocking DVR2s . . . my ears do work, even if listening remains an option! And I'm sure you'll pick up the 'current regulation' queries in the adjacent thread and put us to rights . . .
Bill

Offline trevinoz

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Re: 12 Volt Vs 6 Volt Generator
« Reply #13 on: 10.04. 2009 03:28 »
Hi all,
        the resistance of my field coil is 5.6 ohms and consists of 450 turns of 0.6 enamelled wire, the original 6V coil consists of 300 turns of 0.7
The armature now has 20 turns per coil of 0.7 wire in lieu of the original 13 turns of 0.8. It was a tight fit but I managed. The field coil is somewhat larger but fits with no fouling.
I have been rewinding these generators for over 40 years, I learned as an apprentice and had to apply my skills to keep my Flash on the road as I kept burning out armatures, not knowing anything about the black art of regulators.
Thankfully I applied myself to the regulator mysteries and now strip and rebuild them.
I will supply the speed data some time in the future when I get hold of my mate's tacho.
As an aside re the DVR2 regulator, I overhauled a 1920 Vauxhall generator which had a rudimentary control system consisting of a cut-out and 2 sets of field coils which could be switched manually when charging required, one set of fields seemed to oppose the other. I have no idea how it was supposed to work and in fact the fields were all burnt out.
I asked the owner to get a regulator and he supplied a DVR2 which I fitted inside the cut-out box.
It has been in service for about 12 months now and has had no problems.
  Trev.

Offline RichardL

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Re: 12 Volt Vs 6 Volt Generator
« Reply #14 on: 10.04. 2009 03:33 »
I think this is mostly meant for Snowbeard, considering his/your apparently imminent purchase of DVR2 regulator(s). I don't know if you saw this under another topic. if not, you might find it amusing. It shows how I mounted my own DVR2.

Richard L.

http://www.a7a10.net/forum/index.php?topic=472.msg3927#msg3927
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