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6 Volt or 12 Volt?

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My 1959 '99' is 6V and I intend using it mainly in the daytime so I've restored it as per original with a new PRS 8 switch and alternator stator and rotor.  Is it worth me upgrading to 12V, considering that I'll be using low current LED lights?  I also have NOS 6 Volt Fiamma windtone horns in black instead of the usual red - not that easy to find!

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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  

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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

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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.

In reply to by anna_jeannette_dixon

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Thanks Anna but that doesn't really help.  I don't need much more lighting power, especially as I am going LED, which are brighter and consume less, and I don't intend to do much, if any, night riding.  (All my lights at home are LED now.)  Changing the new alternator isn't an option either. I'd need several good reasons to change. Are there many?

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Sorry, I didn't make myself clear with my question.  It's not what I need to do to change to 12V, it's what are the great advantages that might justify the expense?

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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

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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...)

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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.

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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

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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

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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

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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

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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   

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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.

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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.

 

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