6 Volt or 12 Volt?

hello now 12 volt is a lot better  with a PRS8 you will need a 12 volt  alternator with lighting and Ignition coils  .your anna  j  

I have never had a Brit bike with an alternator, but my understanding is that even the earliest Lucas alternators (they have a smaller OD on the magnet, ID on the coil) will easily convert to 12V with a suitable regulator

Paul

Al, our electrical guru , has stated oft times that you do not need a new alternator to run 12v electrics. If you have an early 3 wire one connect 2 of tham together. Worth a serch through back copies of Roadholder on line. Worked for me, I used a PODTRONIC regulator. Probably you have distributor ignition, in which case Lucas recommended that the internally mounted distributor capacitor is diched and replaced with a 12v rated one which can be externally mounted.

Hi Lionel,

6V is perfectly ok if you are not intending to ride in the dark, and if your LED headlight is good then nighttime riding is probably ok as well.

Just make sure all connections are good and tight and stick with 6V, no point in spending money changing to 12V.

If you intended to change to electronic ignition, then that would be a different matter.

Tony

Even if you stick with 6 volts, it is probably worth fitting a modern regulator - Al Osborne sells one for 6 volts - it should prevent the battery from frying or flattening.  The old Lucas switch system introduced an extra alternator coil to up the output when the lights were used, and you won't need the extra wattage if you have LED lamps.  As Charles suggests above, except for sticking with 6 volts if you feel you must.  But if you are to add a modern regulator anyway, the only reason to stick with 6 volts (since you have an alternator) is to save buying new bulbs and battery.  (Perfectly sound reasons...)

It would be worth checking whether automotive LED lamps will operate at 6v. I would have thought that they would need 12v to switch on. LEDs have a switching voltage which will normally be set for 12 volt usage as that is what most of the customers need.

If you have LED headlamps working at 6v already please let me know. 

Good luck.

Supplied by Paul Goff, it works on both 6v and 12v, positive or negative earth. One lamp does all that, no need to specify the bike voltage or earth polarity. I am not sure if fittings other than BPF are available yet. It is bright but have not yet ridden with it in the dark. BPF beam pattern was always poor so unlikely to be any worse.

Ian McD

Yes, the BPF beam pattern is poor.  I recently fitted a halogen bulb, and it's still a poor headlamp, but a bit brighter.  Riding at night on roads without overhead lights or cateyes is scary, if there is no car / lorry ahead.  Construction and User regulations may apply.....

I have not tried LED bulb replacements, but hear that the beam pattern is poor. 

Paul

Several points of miss information here. You don't need a '12V' stator the RM19 or earlier will 'hold' 12V if needed. LED are in fact 2.6V or there about. The people who 'make' them into a case/bulb etc for use on vehicles can make then Negative earth, Positive earth 6V or 12V as the market choses. It just so happens that the Negative earth 12V brigade-market is the greater, but as is said above Paul Goff is supplieing a multi voltage/polarity item.

6V-12V, yes there is losses with 6V and old wiring, but one of the biggest areas of concern not mentioned above is battery charging. The old 6V system with regulation of the battery charging done by the PRS8 doing its thing, was reliant on a largish 6V lead acid battery venting a bit of electrolyte from time to time if it got a bit hot under the collar-fine for 1959. IF you use a Burlen sealed battery on this system you will cook it. If you use a 4AHR sealed alarm battery (as is becoming very popular) you will cook that too. 12V will allow proper charge control and a better choice of battery and lamps. You can also look at my web site via the orange Icon and find out more. I even have a loom kit specifically for 6V

Besides better output control, going 12V will give a far greater choice of bulbs, whether tungsten, halogen or LED. 

If you are using a pair of Cyclons, you can rewire them in series instead of parallel to make a 6V pairing into 12V.

Paul

I had this debate sometime ago with myself as the bike concerned was 6 volt and very much original. In the end went for an upgrade to 12v as the lights were so much brighter and more importantly you could actually hear the horn. It was thus a safety factor. It paid off when someone nearly ran into me as he heard the horn. I am not sure with the pathetic note before it would have done any good. If I flash the headlight it is also brighter. I only use the bike normally in day light hours to toddle around quiet lanes but when caught out late one evening the 12v beam on a standard bulb helped with night vision and I presume others could see me easier than the 6 volt candle I had. Anyway trust this helps. Cheers Hugh   

When you fit a 12V headlamp we usually go to 45W that is 4A if we fitted the same wattage at 6V it would be 8A, the original wiring had a limit of 8A when new but with 'original' wiring, all those bad connectors etc and the higher current, even the same voltage drop say 1V at 6V is 16% while 1V at 12V the loss is 8% so yes you lose a lot less at 12V. BUT 6V can be made as good/bright, as a 45W head lamp is a 45W headlamp whether it is 6V or 12V assuming you take care of the cable/connection losses. If you can't be bothered about rewiring the bike 'properly' for 6V and sourcing a 45W-6V lamp then go 12V.

Before LED's I would have always recommended converting to 12V, but the actual voltage LED's run internally is 5V then that no longer is the issue. So that leaves you with voltage regulation, fit a 6V regulator, rewire so the alternator is at full output all the time, fit LED's that take 6V and you are  good to go. The LED main bulbs I fit to my 12V bikes all say 5V to 30V, its the smaller ones that you need more care on picking.

If you can solve the two main issues with 6v  then there is no reason to uprate to 12v. Led's  have not had a good press with beam projection but progress is being made.  Charging regulation is a bit haphazard with the psr8 switching and as AL has said a biggish lead acid battery will provide a crude buffer.  The  other issue could be when your 3 wire old alternator dies and you have to buy a new more powerfull 2 wire replacement. Charge control will need a re-think. New PSR8 switches may not be as good(!!) as the orriginals I still have an old one in use. With care and a crafty bit of fine fishing line to hold the springs the psr8 can be cleaned and rebuilt.

Yes this switch is quite amazing considering how old they are-designed in the early 1950s. The rebuilt switches from Far East are not always up to scratch, and when rebuilding (which is straight forward) 1/4 inch becomes 6mm........so swapping parts can become a problem. (see my web site).

It was reported in the Motorcycle Press a while back that the PRS8 was over complicated. I very much doubt if Lucas mad a switch that more complicated than it needed to be, certainly there is several functions within the PRS8 that need some understand and not always needed, but I think Lucas did really know what they doing in the early 50s. I would like some further info re Lucas 1950s-see fresh Post.

Now another piece of 'not quite right' info above-you do not have to buy a 2 wire alternator, the 3 wire RM19 is still available, so you can retain 6V if you want. But you still have to have a74mm rotor.

LEDs are 2.6V ish, if they are made into a lamp housing and they say 5v that is because they have a 5v regulator installed. Which is a very good idea, as LEDs (the raw electronic form) very easily suffer from over current caused by over voltage which does not really cause them to be any brighter. So they can burn out very soon if you over volt them. Cheap ones on my car-said to be 12V soon failed as of course the car runs at just over 14V (14% increase).

Hugh above had a bad horn-blamed on 6V. Not so, a crap horn is a crap horn. You can have one on 6V or 12V. And a decent one on 6V.

My 6v  original  horn from 1960 has been running on 12v for the last 20+ years , and very loud it is too.  Not  exactly a recommendation  but what is there to loose?.

Being not a technical person I changed to 12 v and got brighter lights but an earlier post replying  suggested this may not have been needed being achievable with 6v and newer bulbs.  I only ride really in daylight so the lights were a byproduct (the flash is more visible) but felt really needed a louder horn in today's world. This did prove effective in a potential situation where the horn alerted the car driver to my presence - he not having seen me despite high vis jacket.  I didn't know if this was possible with a 6 volt system at the time not having heard of Fiamm horns. Certainly my replacement horn was cheaper than £60. As I recall I simply combined 2 of the 3 wires from the alternator and changed the rectifier for a combined rectifier/regulator but it was a long time ago. Regards Hugh

To uprate to 12v you only really need a 12v battery and one of Al's A Reg 1 rectifier/regulators and some bulbs. So much better than the dodgy Lucas switching coils in and out setup.

I don't rate LED headlight bulbs. A shockingly useless not to say dangerous beam pattern. A standard BPF is much better. Also, what's the point of generating 100 watts or so and not using them? Might as well put them through the headlight which had the added effect of keeping the reflector and headlight shell warm and dry. Similarly instrument lights - I like my chronometrics to have a little heat source to help keep them dry.

I do use LED stop/tail bulbs though. 

......... came up in another thread.......... I would never use LED's only as perhaps as a rider warning system in the daytime. I know they have advantages in energy consumption but having tested them out on Japanese machinery, a friend and I did a lot of night riding in 2018 and, after seeing how the his lights were slightly brighter, maybe a good thing, however, the light seemed to be less focused, than a standard good H4 bulb, the Osram Night-breaker.  I found the Night-Breaker an excellent product.

We were both riding round Rural Kent avoiding wild life and pot holes and I consider the H4 I was running was safer then the Led headlight my friend was using. Plus he tried LED lights at the rear, great if you were behind him as in a straight line, but viewed from any angle or at a "T" junction and their effectiveness diminished alarmingly, so for me and having experience of their short-falls I  will give LED's a miss.

Apart from specialists projector Headlight designed for them LED's seem to  produce light than scatters rather than that, that can be focused easily. Also when shone through lenses designed for Filament bulbs they doesn't quite work.

I toyed with testing out HID Lights, which apparently are great, but the Law doesn't like them!

A few years back when I had a Honda Civic with good H4 lights, I wondered why everyone was on High-beam driving through Rural Kent and then I got a Mazda with LED lights, the answer was they are pretty crap on dipped beam but much improved on High beam, so much for Road Safety, nearly everybody therefore, was always using High beam with the consequence of blinding oncoming traffic.

LED are pretty crap lights in the home too! Little warmth in the light and they tire the eyes out.

John

I blame John for resurrecting this!

What never got considered throughout this thread was why did bikes run 6v for so long after the rest of the world went 12V. Was it really cost? To my mind it was just as likely that 6V bulbs are a lot more durable against vibration than 12v ones are. I guess that nowadays the revs where vibration is awful are rarely reached by most so it is less of an issue, (or that rubber mounting is better practised!) LEDs are usually quite robust against vibration. Biggest advantage of 12V is you can buy replacement bulbs anywhere so you don't have to carry spares with you. 

A bonus point for LEDs is on safety grounds. When used as a brakelight, LEDs illuminate in 1/10th the time that a tungsten bulb does, so that truck behind you has an extra 1/4 -1/2 second stopping time to not run you over.

Some have mentioned the shortcomings of LED 'headlamp bulbs'. Yes it is true that the first (and 2nd) generation H4 replacements were poor/only adequate, but the latest are really good with a good beam pattern- 5000 lumens good. Was the issue with the first generation market driven? Was it an issue ramping up production too fast? Technology not quite there?

It should be remembered that tungsten filament bulbs only became mainstream in the 1920's and I'll bet at the time that there were people insisting that the acetylene lamps they had on their bike/car were far superior to the new fangled bulbs.

So Tungsten lighting has 100 years of development, Quartz Halogen has 50 years, while LED's have only been realistically affordable in the last 10 as replacement bulbs. I expect that within 5 years we will wonder what all the fuss was about.

Funnnily enough acetylene lights are remarkably effective, much better than an early 6 volt 24 watt headlight and not dependent on a 36 watt dynamo. It was all the faffing involved that really put paid to them.

One thing I do like about incancescent bulbs it that they keep the nearby electrics warm and dry. The only LED bulbs on my machines are stop/tail bulbs. Your normal BPF bulbs are fine as long as you have decent wiring and a proper earth wire.   

They gave much better lighting than oil lamps. There are some drawbacks with them. There is no practical way to have a dipped beam option. Not a problem when traffic was slow and sparse. If of the carbide and water variety, it was a bit fiddly to recharge and adjust water flow to get right amount of acetylene produced. If the kind with a cylinder with compressed acetylene, shops where you could exchange them could be hard to find. To turn the lights on, you had to stop the bike, light it and restart. Turning on a switch was much simpler.

Fitting a Podtronic on a 650SS. All the instructions says it's simple!

My alternator has three wires. Currently the green/yellow goes to the the bullet connector at the top of the sprung caliper thing on the switch. Instructions say that this wire now connects to one of the yellows on the Podtronic. Can I/Do I now forget that particular connection to the switch?

I understand that the black wire from the Podtronic (+ve earth bike) will connect with the old Brown/purple off the rectifier which goes to switch connector position 3  which in turn goes to the battery via the ammeter. That one is fine.

However, one of the double green/browns off the old rectifier goes to switch connector position 1. Does this connection get scrapped or do I need a double connector off the new podtronic yellow to run a replacement wire to switch connector 1?

Lastly, one of the double white/greens off the old rectifier goes to switch connector position 7. Again, does this connection get scrapped or do need a double connector of the second of the new Podtronic's yellow wire to run a replacement wire to switch connector 7?

Sadly none of this covered in the instructions. Any help gratefully received.

Wiring diag attached.

Thanks

I orriginally switched to 12v some 25 years ago to get brighter lights ,indicators ,readily availiable bulbs and Electronic ignition . Decent voltage control (zener) and a new cheap encapsulated rectifier. Thats all still working . What I did not then consider was the need for a power point for satnav ,phone charger, automatic chain lubricator , heated jacket ,grips.and onboard compressor to pump tyres. I now have these too, and Daytime running lights.My battery is always fully charged. I can even make a fresh cup of tea . Tetleys of course!.Have not yet figured how to fit  a chiller for the milk/Grolsh beer./ sandwiches. The car has one in the glove box as standard.And there is still some unused space under those DL panels as long as I don't fit those air horns.

the 1961 ES2 I bought for rebuilding has 6 coils of which 4 have thick wire and fewer turns, and 2 coils have fine wire and many turns. I have been told that Norton never used this system, it is an old system with HV voltage for quick starting.

The stator has now been installed with 2 pairs feeding a battery and the coil. The HV windings are not used.

Now, there is no charging - even with no consumers on other than the coil, until about 35 - 40 mph in top gear. Around town the battery will go flat.

Not realizing that the '61 ES2 was 6V, I have fitted a 12V battery. It has a Wassell control box/rectifier fed by 3 wires from the stator, the fourth wire is not connected.

To improve the charging, should I have the HV coil pair rewound as the LV coil pairs are, or fit a 6V battery, or anything else that someone cleverer than I am, can suggest?