Introduction to 12 volt conversions
Many old British bikes, including my 1951 Matchless G3Ls, were originally fitted with 6 volt electronic systems. Now I’m not sure exactly why 6 volts was chosen, but I’m guessing it’s something to do with the ‘cell’ voltage of a lead acid battery being around 2.1 volts and three cells giving a battery unit of a convenient size.
The starting point for me - my problematic 6v battery
After a few decades, manufacturers switched across to 12 volt systems instead (possibly as battery technology evolved) and this was much more suited to automotive applications such that it persists as the standard voltage for cars and bikes today.
12v systems are less susceptible to the effects of resistance in the wiring loom. For any given power, a 12 volt system needs to supply only half the current (Amps) of a 6 volt system and hence resistive losses in old wire, through rusty or lose connections, or thin wires in poor quality switches etc and much less of a problem.
However, the main advantage for classic bike owners of converting to 12 volts is the better availability of modern bulbs and other electrical accessories (including batteries, horns, LED bulb conversions, etc) at this higher standard voltage.
In the case of my Matchless, I had initially wanted to stay with the original 6 volt system. However, whilst living in India, I found that good quality 6 volt bike components were incredibly hard to track down. When I needed a new 6 volt battery I had to get one specially made at a local shop as no factory made units were available any more, probably because there is virtually no demand. Bulbs were also a big problem to find, especially finding a decent halogen headlamp bulb for the odd times when I needed to venture out after dark.
However, the final straw came when the 6 volt battery I had specially made started to fail after only 3 months or so of service. It wasn’t charging properly, neither on the bike or using a mains charger. I didn’t really want to bother going to the hassle of getting another one made if it would only last another few months. On top of this, I was looking to fit some indicators to the bike in the near future (to make riding feel that little bit safer) and preferably wanted to use LED bulbs to minimise the additional load on my small Lucas dynamo. But these are hard to find in the 6 volt positive earth variety!
This article contains the following sections:
- Introduction to 12 volt conversions
- Converting to 12 volts
- Step 1 – Selecting the 12 volt parts
- Step 2 – Out with the old, in with the new
- Step 3 – Rewiring the regulator
- Step 4 – Refitting the battery and fuse
- Step 5 – See if it all works!
- Conclusions and your comments
Converting to 12 volts
Now I had previously fitted a modern solid state “DVR2” voltage regulator from Dynamo Regulators Ltd to my Matchless after the old mechanical Lucas AVR started playing up. You can find details of the installation in my guide here.
The old Lucas and new DVR2 voltage regulators
One feature of this regulator is that it can give a selectable 6v or 12v output from a standard 6v Lucas dynamo, so this gave me the opportunity to convert to 12 volt electrics with just some simple rewiring and changing a few bulbs.
Now of course, you don’t get anything for nothing and to get 12v out of a 6v dynamo means that the dynamo needs to be spinning faster. There are various options to rewind the dynamo to give 12 volts so that it gives the higher output at standard engine speeds, but the expense and availability of parts in India meant that this wasn’t an option. At least not for the time being anyway.
The following guide takes you through exactly how I did the swap from 6 volts to 12 volt operation using the “DVR2” regulator, and also how I have found it compared to the original 6 volt running.
Step 1 – Selecting the 12 volt parts
I just need to borrow a few bits...
The first step is obviously to get some new 12 volt parts for your bike – mainly bulbs and a battery. I decided to leave my existing 6 volt horn in place as that should work fine on 12 volts (at least for a while!) and as it’s a cheap pattern part I’m not too worried if it eventually gets fried. If you have the original Lucas unit you might want to swap it though to avoid damage.
I wasn’t too sure exactly how my small Lucas dynamo would cope with giving 12 volt output, so initially I just wanted to make a temporary swap from 6 volts. Therefore my other bike (a 1970 Royal Enfield Bullet) provided a useful temporary donor for bulbs and battery.
Step 2 – Out with the old, in with the new
Start by disconnecting the old 6 volt battery to avoid any shorting issues whilst you fiddle with the other electrics. Then take out the headlamp, pilot lamp and tail lamp bulbs and replace with the new 12 volt versions.
Make a double check around the bike to make sure that you don’t have any other 6 volt electrical items fitted that could be fried at the higher voltage (especially if you have electronic ignition).
Step 3 – Rewiring the regulator
Insulating the 6v regulator wire
Rewiring the “DVR2” voltage regulator to operate at 12 volts is a simple case of removing a single wire from the ammeter connection. In standard 6 volt operation, both the brown and white leads out of the regulator unit are connected to the ammeter.
For 12 volt operation, you just need to remove the white wire so that only the brown one is connected to the ammeter. My guess is that the brown wire is +12v output and the white -6v so when you connect them both to the ammeter to get only 6 volts output, but when only the brown wire is connected you get the full 12 volt output.
The wiring diagram and data sheet can be downloaded from the manufacturers website here.
With the white wire removed from the ammeter connection, you then need to make sure that it is insulated so that it doesn’t short on the frame etc. I used some heat-shrink tube to cover the bullet connector at the end of the wire. I guess you could just cut this off, but that would make it more difficult to revert back to 6 volt operation in the future if needed.
Step 4 – Refitting the battery and fuse
After a quick double check of the wiring to make sure it all looks in good order, the new 12 volt battery can then be installed.
It is advisable to have a fuse installed in the system to protect it in case of short circuit. In 12v mode, the current needed to power the various electrical components will be halved (assuming you have fitted like-for-like wattages) as power (Watts) = voltage (volts) x current (Amps). It is therefore sensible to reduce the fuse rating installed to ensure full protection.
Lastly a change of the main fuse
When using 6 volts, I had a 15 Amp fuse fitted in line with the battery. The rated output of my dynamo is about 45 Watts (it’s the shorter Lucas type, the longer ones are around 60 Watts) which at 6 volts equates to a current of 7.5 Amps (45W / 6v = 7.5A). A 15 Amp fuse is probably a little on the high side (10 Amps could have done) but I didn’t want it to keep blowing all the time so I thought I’d try 15 Amps as a starting point.
At 12 volts, the current will be halved so the 45 Watt output of my dynamo equates to a current of just under 4 Amps (45W / 12v = 3.75A). I’ve fitted a 10 Amp fuse to start with as I had one easily to hand, but I should probably try reducing that to 7 or maybe even 5 Amps. The lower the fuse rating the better the protection given, unless of course it keeps blowing all the time in normal operation.
Step 5 – See if it all works!
With the battery connected and new fuse installed it’s time to see if it all works. Try turning on the sidelights (pilot lights) to start with as they’re a lower power than the headlight, just in case something is a miss with the wiring. If that seems good, try the headlamp and brake lights. Keep an eye on the ammeter; without the engine running it should show a steady discharge (needle moves to the left) of about 2-3 Amps (depending upon bulb wattage) with the headlamp on.
If all seems well, start the engine and then recheck that all of the lights are still working. Now is probably a good time to go for a test ride, although a run in daylight with all the lights on is sensible just in case there are problems, rather than going straight out in the dark!
Check the ammeter reading as you ride a long at cruising speed. With the lights all OFF it should show a positive charge (needle moves to the right) going into the battery. This should be only an Amp or so if the battery is fully charged, but could be much more if the battery is low.
At low speed with the headlamp turned ON the ammeter should show a steady discharge, but as engine speed increases the discharge should reduce and at cruising speed it should just about balance (needle in the centre). If the ammeter still shows a considerable discharge even when riding along at reasonable speed, then it is unlikely that the charging system can cope with load you are asking from it for any extended duration. In this case you should maybe consider reducing the headlamp bulb wattage or perhaps changing other bulbs to LED types which need much less current (see my guide here).
Conclusions
And that’s about all there is to it! You now have a 12 volt Matchless and a world of cheaper and more readily available bulbs, batteries and LEDs at your fingertips. The great thing about the DVR2 regulator is that you can easily go back to 6 volts at any time just by reconnecting that extra wire. Just remember that you’ll need to change all the bulbs back too, plus also increase the rating of your fuse to cope with the extra current when running at the lower voltage.
I’d just like to point out that I have no connection whatsoever to any of the companies or products I have mentioned, other than in the case of the DVR2 regulator product having fitted one to my Matchless and been quite pleased with the results. Please make up your own mind about the suitably (or otherwise) of any products or services for your own requirements as these may be different to mine.
[sc:disclaimer]
Hi James,
just wanted to say how much I like your blog for its clarity and your demystifying approach to classic bike issues. Not just because you say nice things about our DVR2 dynamo regulators.
I will add a link on our Q&A page as you cover some common electrical issues in more detail than I can hope to.
Kind regards,
Mike
Thanks Mike. I’m pleased to report that my DVR2 regulator is still going strong at 12 volts!
Hi James,
If you still have the lucas 6v regulator, please give it to me. I am restoring a 1951 matchless g3ls. Please help me.
Sir. I have riding a yezdi 250 cc model B for the last 39 years almost. The bike also used a 6 v battery only for horn tail light and brake light. Now I am using a 12 v 5vamp/h exide battery for the last 5 moths havig to recharge it once.I checked the outgoing voltage (to the battery) to be ok around 12.5 but at fast rpm.Atwhich the bike will attain a speed of atleast 55kmph. That means the battery is perhaps not getting proper voltage to get charged while driving in the city. The magneto os 12v and high tension coil a.lucas 6v
Please advise if the DVR2 WILL COME HANDY IN SUPPLYING THE REQUIRED VOLTS TO THE BATTERY AT IDLING RPM. YOUR EXPERT OPINION IS EAGERLY AWATED.
RAMMOY. ALLAHABAD UP. INDIA
Hi Rammoy. Sorry, but don’t know anything at all about Yezdi bikes. Does your bike have a dynamo or alternator? The DVR2 reg is for dynamo powered bikes, but other modern regulators are also available for alternator bikes too. If your current dynamo / alternator can supply the requires 13+ volts require to charge a battery then a modern regulator will definitely help. But it all depends on your bike’s electrical system. Sorry can’t be more help – I’d find yourself a Yezdi expert! Regards, James
Thanks Mr James for the promt reply. Iam a diehard fan of Yezdi which I have been riding for the past 39 years almost. Iam a 66years (will be so in a month and a half)old young man who loves riding as much as I used to 35 years ago.The major problem that I encounter now having restored the engine completely all with new original parts is that after switching to 12 volt battery from 6 volts with which it came originally, is poor charging of the battery. I guess the proper incoming voltage to the battery should be between 12.6 to 14 volts for charging.Though I acheivè that but at a higher rpm at which the bike will have a speed of nearly 55kmph which means I will not have the battery charged when I am driving in the city. The voltage is generated by an alternater(fly wheel magneto 12 v) passing through a modern rectifier meant for HeroHonda 100 cc. Battery is 12V 5amp/h Exide with negative earth. Will a DVR2 help. Head light is operated by dynamo and the bulbH4,HS1 is frequenly fused(magneto is black in colour) please advise
Rammoy.
did go ok on 12v or not I have a Gl3 1947 and I mite give it a go on 12v thanks mate
Hi Tony,
Yes, my bike has been running great with 12v electrics. Much easier to find 12v bulbs, especially for the headlight. You have to rev the engine a little higher to get full output at the higher voltage so the battery doesn’t charge as much in slow-moving traffic, but other than that no problems at all. Worth swapping across to some LED bulbs though (check out some of my other posts) to save a few Watts of output. I’d strongly recommend the DVR2 regulator described in the above article.
James 🙂
An interesting article, but it would be nice to know your experience of the 12v system compared with the 6v system. You say you will make this comparrison, but I couldn’t see any discussion on this point, only how to test it. More technical details about what exactly you load was (6 & 12 V) and you dynamo output rating. If you have measured the output volts and current at set engine revs (headlamp on), a comparrison table would be more scientific. Keep going.
Hi Geraldo. Thanks for your comments!
I’ve just had my dynamo serviced (it’s a short Lucas ~42W E3NL unit) and will be rebuilding the bike in the next week or two, so I’ll try to revisit this article then and make some updates.
A table / graph of dynamo output versus engine speed would indeed be useful wouldn’t it? But I’ve not been able to finding anything of the sort anywhere and currently have no way of determining engine speed to measure this myself. Maybe that’s something I will look into in the future. Realistically though, I could only measure dynamo voltage vs. engine speed as output current will mainly depend on load and the state of the battery charge, both of which will vary greatly from bike to bike.
But if anyone has any suggestions then please let me know!
Regards, James 🙂
Thanks for such a clear and patient piece. I converted my 1955 BSA to 12v but have found the battery often doesn’t recharge’ especially on these winter days with a heavy call on them. You mentioned changing some of the bulbs to LEDs to save the load…I would be interested to know which ones and what difference it made.
Hi Raglan,
Glad you found my post useful. With regards to installing LED lighting to reduce the load on your dynamo / battery, checkout this post:
https://matchlessclueless.com/electrical/lighting/led-lighting/
Hopefully that should give you some ideas to get started.
Regards, James 🙂
Hi James,
I just stumbled accross your website & I find it most interesting. A really great guide for people who could be having problems. I have fitted a DVR2 to my 1953 Matchless G9 converting to 12v & I am so pleased with it that I intend to covert my other classics as well. Also fitted to my G9 is a Pazon Ignition system. Absolutely brilliant. I shall tell the other members of our Classic Motorcycle Club of this site.
Cheers, Richard
Hi Richard,
Thanks for your king words and glad you found this site useful. Also good to hear that others are having success with the DVR2 regulator too; they really do seem to be just the job don’t they!
Regards, James
hi guys- has anybody converted an AJS/MATCHY with an alternator,from 6 to 12 volts. I have just done this,changing the bulbs,coil etc. and using a modern solid state rectifier/regulator ( 4wires,2 yellow and 1 red and 1 black) Bike starts and runs fine WITHOUT the lights on,but upon putting the lights on, discharges the battery quickly. This bike has the seperate. multi-pin(s) ignition and lighting switches.Because the alternator wiring has been changed as per normal ( i.e. joining the black/green and yellow/green wires together)Do I have to link the lighting switch and ignition switch somehow as the charging was dependant on the light switch position originally.
Thanks for any help. The bike is a 1962 350 single ( Sceptre)
Tony
Sorry Tony, I’ve no experience of converting an alternator model to 12 volts. Sounds like a wiring issue to me though. Your best bet is probably to speak to the supplier / manufacturer of the regulator unit you are using to confirm the correct wiring connections.
Good luck! James
Did you need to change coil to 12 volts or is the 6 volt original one coping?
Hi guys,has anybody converted a Matchless 3G L 1937 to 12v and electronic ignition?
Hi Andreas,
You mean a 1937 “G3L”? Conversion to 12v should be no problem following the guide above using a modern electronic regulator (get a DVR2 is my recommendation!).
Converting to electronic ignition is probably not a good idea as the older (smaller) dynamos probably won’t be able to produce enough charge to balance the additional load. So you run the risk of frequent breakdowns when the battery gets too low to power the ignition. You’re best of getting your magneto professionally refurbished if you are currently experiencing problems with it.
Hope this helps, regards, James 🙂
Hi James,
Thank you for the the great article! Can you please advice regarding my 1964 AJS Model 18 (alternator). I’m considering the DVR2 12v conversion as you have described above. Can you recommend this for an alternator electric circuit motorcycle? Is it possible to use your instructions as a general guide for this bike? What will the disadvantages be?
Kind Regards, Petrus
Hi Petrus,
As far as I am aware, the ‘DVR2’ voltage regulators are designed for use with dynamos only, not alternators which are completely different in operation. Also is your alternator not already 12v?
You might hopefully pick up a few general tips from the article above (e.g. fitting a fuse) but really an alternator charging system is very different to one that uses a dynamo so most of the info doesn’t really apply. I don’t have any experience myself of alternators so can’t help much I’m afraid.
Regards, James
Thank you for your reply James. Upon further research it seems like I can convert my 6v altenator electrical system relatively easily with the following parts: 12v regulator (negative earth), 12v bulbs/LED’s, 12v Coil, 12v ammeter, 12v horn, Fuse.
Do you think I’m missing something? If anybody read this with some experience or just a tip that might come handy please reply. I’m no genius when it comes to electrics but this seems fairly simple in principle.
Great products in your online shop James!
Kind Regards, Petrus
Sounds like you’re on the right sort of lines Petrus. You don’t need to change the horn as the 6v one will continue to work fine at 12v for occasional use. Also the ammeter doesn’t have to be changed as the current will be halved at 12v.
you obviously know where you can come for an LED light unit! What type does your bike have? I’m currently developing models for the later Lucas lamps – see here for more info:
https://matchlessclueless.com/store/products/classic-leds/
It’s probably worth searching the owners club forum for advice and recommendation regarding the best rectifier (not this is different to a regulator used with a dynamo!):
http://www.ajs-matchless.com/forum/
Good luck, James 🙂
I’m ordering 12v Lucas 564 LED light board, thanks!
Looking at converting to 12v negative earth on my 54 G3LS. (The AFS one shown on your web is actually mine). Would a 3.0 Ah battery in an empty Lucas battery box be adequate? Something like a CB3L-A? Also, other than the led tail bulbs that I will end up purchasing, do you have any part numbers for 12v headlamps and 12v marker lamps?
Thanks for this web site! -Brett
Just read the article you wrote regarding battery selection. Clearly 3.0 Ah is not adequate. I can buy the Cyclon batteries here in the states and will do so. Still interested in part numbers for the 12v lamp conversion.
Regards, Brett
Hi Brett. As you say, 3Ah isn’t really going to be enough. There are no part numbers for the 12v headlamp and marker lamps as such, just find a 12v version of the 6v bulbs you already have. Might be easiest to take them along to you local auto store to compare; the bulbs should be fairly standard types and readily available in the higher voltage variety. Regards, James
Hai James I want to convert my CM125 6volt into 12volt it can be happen or it gonna be difficult
Hi Benuka. It is probably possible, but how difficult, expensive and worthwhile it is depends upon how many parts you need to replace. Sorry I have no experience with these bikes. Start by looking for a 12v regulator/rectifier and then work from there. Regards, James
Hi all. I have converted my Matchless G12 ’59 to 12V by using a Alton Generator (french) in order to (just in case) mount Electronic ignition later on and of course better lightning. It works like a charm. Later on in tthe proces i have also fitted a external consenser to my mag unit. Now i am also capable to restart the mc even tho the mag is very hot.. Many Regards From Anders Viking (Denmark)
please furnish the details as where can i get this in india and how?
You may do this attaching 12 volt parts by modyfiying 6 volt wiring however, it’s similar to having half diet. To optimize performance of electrical devices on your bike is to modify magneto coil. 6v engine might give you 6v but on higher RPM. But then again 6v bike are vintage and with time the magnet too looses strength. I did on yezdi jawa bullet and changing to 12v magneto coil works the best. The electrical system on the bike becomes as good as the latest ones. Even HID system works good. For bullet you can easily get 12v coil. Challenge here is getting 12v magneto coil for jawa matchless, norton, usually I don’t get them market cause these bikes were never manufactured with 12v. So the best way is to disassemble the magneto coil and find a good auto electrician who can do the winding job for you to optimize it.
What ampage or battery number did you use for the 12 volt conversion, thrts so many different ones. I have same setup as your matchless. Thanks
Hi Andy. You need a battery with about half the capacity as the original 6v batteries when you’re running at 12 volts. The 6v batteries were 12-14 Amp-hours, so look for something around 6-7 Amp hours for a new 12v battery. Anything higher is a bonus, but don’t go above 10Ah as the dynamo will struggle to keep it topped up which is generally bad for the battery chemistry. There’s more info in this article:
https://matchlessclueless.com/electrical/general/battery-selection/
Hi I have 1983 Hondacb125t twin cylinder.
Its 6v can I convert it to 12v.
Since its difficult to find 6v parts.
I have a 1964 Honda dream motorcycle. 6 volt and want to change to 12 volt. what happens if I just put in 12 volt battery and go ? do I melt everything ? thanks BILLY
Hi Billy. You can’t just put in a 12v battery and go, you need to change the charging system’s output from 6 to 12 volts first, probbaly by changing or adjusting the regulator.
by regulator , do you mean stator and how can it be adjusted ?
Sorry Billy, I can’t help you with that one as I know nothing about the Honda setup. The regulator (or rectifier if an AC system) is the circuitry that the dynamo (alternator) output is fed into. Check out the wiring diagram for your bike to see how the charging system is configured. Regards, James
Hey there! I’ve been reading your blog for some time now and finally got the bravery to go
ahead and give you a shout out from Atascocita Texas!
Just wanted to tell you keep up the great work!
Great site most helpful.
Hi James’
I understood that the 6V system (on a lot of cars pre war) was superseded when piston compression rates were raised too high for the starter to handle. Didn’t bother us bikers with no starters!
Thank you for your wonderful effort.
Thanks Terry. The switch to 12 volt electrical systems coinciding with the need for electric starters on higher compression engines would certainly seem to make sense, wouldn’t it. I guess we’ll probably never know for sure, a bit like pondering why various manufacturers went back and forth between positive and negative earth systems, but your theory would seem to be a very feasible one.
Glad you found the article useful. James 🙂
Am currently running a 6-volt 3-brush negative earth Miller dynamo on a 1938 Panther 600. The dynamo has two terminals, +B and SH. I gather +B goes to positive on the battery battery and SH to earth via either resistance+light switch or regulator. I have a lead from the positive of the battery to the ammeter. The take off for lights is on the opposite side of the ammeter and the lights are earthed or returned to the negative on the battery.
The dynamo cranks out 6.5 volts when tested across it terminals, but when the bike runs, there is nothing shown on the ammeter.
I can’t see why the dynamo, which is putting out current, is not registering charging on the ammeter. The dynamo has been rebuilt and clearly works.I am using a 6 volt diode, negative earth, and connected correctly in the dynamo to replace the original Miller mechanical cut-out, which was wrecked.
All advice welcome.
Hello….I have a 1978 Yamaha IT250 that I converted to 12v. It seems to keep burning up the Ignition Coil…3 so far, in quick dispatch. In the mag, it has a lighting and a primary coil. Now my CDI is factory set to operate a 6v and I am having problems. I have installed a key switch, handlebar switch, h. light, t. light, turn signals, battery, horn and etc…all works for a bit the NO FIRE….Is there a conflict with my 6v CDI and my ‘now 12 volt’ system??? using the 6 volt CDI…do I need a 12volt cdi, somehow?
Hello….I have a royal Enfield 1959 350cc motorcycle. I am planning to change it to 12v. so, is the above procedure useful for me
please help
Hi Traison. Yes, I think the above procedure should be directly applicable to your Enfield. You just need to get yourself a modern electronic regulator, and my recommendation is t get a DVR2. But first work out whether your bike is positive or negative earth!
Regards, James
Hi James just a quick note Im converting MY Yamaha TT350 lighting to 12v reading step one of your article to disconnect white wire leaving brown ( my regulator has yellow/white wire and my rectifier red & white ….. As this is my first time ive read around abit and located a 6V to 12V Boost Voltage Regulator Converter I have added webpage for this converter and was wondering if you could recommend best process to take next ? I have 2.3AH GEL 12V Motorcycle Battery , I have 12v H4 halogen 60/55w & 12v lead light indicators & 18 LED Brake Reverse Light Bulb Globe 12V Just figuring out if I should wire up the 6v to 12v booster ? Or open to your best solution ? cheers johno
http://www.ebay.com.au/itm/131793191220?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT
Hi James,
I am currently in the process of converting my Royal Enfield bullet 1969 model from 6 v to 12v. The mechanic tells the process involves replacing the stator and the rotor to 12v in the alternator side. And the rectifier obviously. Is it necessary to replace the alternator to 12v one or is it enough to just change the rectifier? I plan to have a DC headlight so as to get a constant output in lower rpms. Kindly suggest me on this.
Hi Pratham,
From “LUCAS Fitting Instructions for converting 6 volt alternator equipped motor cycles to 12 volt:” The original stator and rotor except energy transfer units, are retained in every application providing they are in good working condition.
The mechanic denied retaining the old stator and rotor. I ended up replacing stator, rotor, rectifier and wires in the conversion process. And of course, the lights and horns.
Hello Everyone,
I have Honda c70 1980, 6v point base current motorcycle and i have tried alot to ask hundreds of motor mechanics to convert my bike from 6v to 12v but regretfully still unsuccessful to find one.
It is my humble request if someone from you all gentlemen willing to help me out on this so please contact on my email [email protected].
Thank You.
How much did you spend in total, all parts and battery ?
Hi admin, i must say you have hi quality posts here.
Your website should go viral. You need initial traffic boost only.
How to get it? Search for: Mertiso’s tips go viral
You run a very valuable blog. However, the issue with converting to 12 volts ultimately boils down to how the dynamo can take heat. V=1r, so a 12 volt system with 3ohms resistance will pass 4 amps. A 6 volt system with a 3 ohm resistance will pass 2 amps.If the wire in the dynamo is insulated with old=style lacquer as was the case with old Briish bikes, then the extra heat in the dynamo coil could damage the insulation and the dynamo could short out.
Watts (power)=volts x amps. So given a 3amp output and a 12volt potential then the dynamo output is 36 watts, in contrast to a 6 volt system with 3 amp output giving 18 watts. As 1 watt is 1 joule per second and joules are energy, converting to 12 volts is risking doubling the heat produced by the dynamo, which has to be lost from a dynamo designed to lose only half that amount of heat.
Or so goes the theory. If the 12 volt conversion works, then fine, the system can take it and you will have a brighter headlight which is no bad thing, especially in these days of these damnably dangerous LED lights on assorted vehicles.
sir, my father had a cg125 honda,, 1990 model,, its been stocked for almost a year,, i decided to make it work again, my problem is, its 6volts, and i want to make it to 12 volts,, i think bulbs, regular/rectifier and the battery will be replaced with 12volts,, is there any other will be replace or to be rewired??? please help me sir,, thank you so mush for your help sir, god bless
I have yezdi 250 1968 b class it’s 6 v motorcycle how can I convert it to 12 v can anyone help.
Hi Prashant. Sorry, but I do not have any info regarding Yezdi electrical systems. Regards, James
Hi James,
Pleased to see you are still doing the good work. May I wish you a healthy, happy and prosperous New Year.
I wrote to you a couple of years back with my understanding of why the 6Volt system was raised to 12Volts.
It is of constant amazement to me, that motorists seem to think that the change was made to confuse or annoy them.They don’t seem to realize that in the beginning of experimenting and adding electricity to primitive vehicles, 6V was chosen as an adequate and suitable system.
As the world progressed and got faster (higher compression ratios) and more demanding, (signals, lights, radios, storage) other voltages were tried: 12V, 18V, 24V and 36V and eventually agreement was reached that 12V satisfied all requirements.
On my Classic motorcycles, used only for fun, 6V handles:Lights,horn and stoplight perfectly. The magnetos provide ignition, but the downside is getting 6V bulbs and of course if one wants to add: Indicators, air horns,clocks,radios,satnavs and any other electronic equipment 6V is not capable.
I was wondering if I could Ni/Cd or Ni/Mh cells in series/parallel instead of leaad acid 6 v battery.Will they get charged ?
Hi Ravi. No, that’s not a good idea. NiCd and NiMh batteries require special chargers and very precise voltages to charge them. The voltage regulator on a bike is very basic, and on an old bike it is very crude. The voltages can be up and down and all over the place. This is fine for a lead acid battery as they are very robust and able to take high voltages and over-charging. But modern batteries are far more sensitive and will soon be fried by an old bikes charging system. Nice idea, but no, it won’t work long-term I’m afraid. Regards, James
Hi James, I just got a 1960 Royal Enfield bullet with original lucas 6 volts system. Recently I had some problem with the battery and temporirly I fitted a used 12volt battery without doing no other changes. I noticed that the lights and horn are working fine. Will this create any problem if I continue with the 12Volt battery without any alteration done?
Hi James I want to convert my c70 into 12 volts is there difference with your procedure? Please help me.
Hi James my c70 Honda operated with 6 volt rectifiers regulator is it OK to fit with DVR2 regulator by converting it into 12volts? Is there a rewiring to CDI and to stator?
Your avid fan:
Del
Hi Del. To be honest I’m not sure as never looked at the electrics of a C70. I would contact the guys at Dynamo Regulators (who make the DVR2) and ask them. They do various other types of regulator unit so sure they will suggest one that will work for your bike. Regards, James
Thank you James.,pls tell me whats the regulator that fits to my c70.
Thanks:
Sorry, I’m not really sure. Best to speak to the manufacturers for their advice. They are very helpful! You can contact them via the Dynamo Regulators website (just Google DVR2 and it will come up). Good luck! James
Mike where did got the wiring job done in Hyderabad I Want fix my bullet in same way as you never know when do you want to revert back to 6 volt.
May i know what indian enfield year model bike is shown in the beginning of the wiring tutorial
Hi Haseeb. From memory, the RE Bullet was from about 1970. But it wasn’t a very original bike with lots of bits changed over the years, so there are probably many parts from newer models on there too. Regards, James
I am working on a ’71 Yamaha that is a 6v – is the conversion the same even though it is not Lucas electronics? Also did you need to replace the condenser and capacitor?
Hi
I have Matchless g3l 1949 this is 6 volt dynamo I to like to convert 12 volts. Guide be please.
regards,
Can i use 6v battery in place of 12v battery in hero honda bike. Is it work out?
Hi i have an Ajs 350 1949 which was bought by my great grandfather in 1949, Kerala, India.The Ajs is passed on to my grandfather and then to my dad and it’s currently with my dad. There is a an emotional connection to this Ajs for my family. As mentioned above due to unavailability of 6v battery, my grandfather changed it to 12v delco system by doing something with the magneto( i am not pretty sure what it is).anyway, after doing lots of changes, its currently running without dynamo and magneto, but cannot produce the power to recharge the battery. Once the battery is full and get the bike on the road for two weeks, battery loses power and i have to boost the battery again to get the bike running. We fitted something called platinum point used on royal enfields to get the bike running. Now, there are no platinum points available too. Please help me out. I really need the bike running.
Dear all fans,
I am 84 years young,restoring a 1954 Triumph Terrier.t 15 in Bangalore for my Son im Houston Texas ss a second owner only.He is sending me msny parts ordered
on line like full clutch assy.kick starter spring,gear position finger,gear cable etc
He is unable to get the original all aluminium rectifier that sits under the single seat amd eas advised to get a cheap solid staye one instead.
I have all original parts,headlights tail lights,original seat,tank rubbets
et al.I refuse to compromise and insist on the original al.rectifier.Where on this planet can I get one?HELP
If I change to a 12 v setup,will this al.one have to be scrapped?
Great guide James, I converted my 650 triumph pre-unit from 6v to 12v, all led bulbs. Battery even charging up when pootling along at 40 – 50mph in top gear with all the lights on. No longer dimming when the revs drop, lights are really bright and the 6v horn makes a proper horn noise! Best thing is I can now use a 12v sealed battery with no silly vent tube that keeps falling off causing my battery box to rust!
now if your still kicking as time does not stand still James its 16/1/2023 i have velo 250 mac came from a garden 62 years it lade . 9 months on it looking ok after the hard work. I need to please the harness new I have. I just was thinking over the last day or so. if I could go from 6v to 12v.
i check the net and your site came up. i save your info to my pdf file.
i bought my first AJS 350 ,at 19 years old.in 1973.£20 .i travelled 40miles a in snow and ice to work. it 80mph .one winters day it sized up. The cops pulled up. We got you . the ask my wear i was working i seed 3 miles from hear. If you push the bike to your works .i let you go ok. and no more speeding. i bought a AJS 650. 100mph two up.i gave it my brother as a gift. he sold it be hind my back .wears the years gone .the only problem i had it would blow the front pipes of on the motorway would get home with melted boots. A great bike .from carlisle uk keep safe and live long by all.
Hi James. Nice work, i’m reading it in 2023 and i think is a great idea. I’m working on my motorcycle since 2020, is a Moto Guzzi Lodola Granturismo (235cc) with a 6 volts electric system. Now, i’m waiting the painter work to reassembling everything. I wish to convert all the old elecrtric system to a new with the Motogadget items (M-unit blue, Mo-button etc etc) that works in 12 volts. At this moment, with the opld elec sys i can’t. Reading your post i think i can convert all ths system to 12 volts using a Li-ION battery and all the digityal instruments and items i want. Thank You for your help.
Hi Mark, i’m reading your post and i feel so anthusiast on your goal. Now i think i can upgrade my Guzzi Lodola to 12 volts!!
James, thank you for this. I currently acquired a 1952 Bullet here in Mumbai, India. I’m a big fan of MagDyno’s and was on the fence about a 12V conversion.
Coincidently I already purchased and have a brand new DVR2 waiting to be installed, I got that tip from Andy Tiernan and Peter Ranson.
My MagDyno works just fine but currently have omitted the Dynamo and running 12V straight for the ancillaries and doing the manual charge for now.
I probably will end up buying an entire Magdyno which needs TLC and fully re-build both and replace the Lucas E3LM’s 6-volt armature for a 12-volt one. I reckon that way I’ll have 12 volts and will also have my original working MagDyno unmolested.
The situation of finding 6V components has improved a little, 6V sealed batteries are not that hard to find here in India, bulbs and other components can also be bought in bulk. So, it’s probably not as bad as it used to be.
I’m fine with 6V or 12V either way as long as the system works and is charging. Don’t care particularly about the brighter lights or a stronger horn since it is stupidly dangerous to ride valuable classics in modern traffic which is seemingly filled with imbeciles, it’s a death trap anyway, lol!