6volt or 12 volt?

[3564cam]

Hi,
I am currently restoring two bikes,a 250 Mach 1 and a 450 series 1 scrambler.My question is, would you keep them as 6 volt or shall I convert them to 12 volt.I intend to use them both as much as possible.Your advice on any other things you would recommend like more powerfull alternators would be appreciated.
Steve

[JimF]

Hi Steve,

You'll find a lot of information on converting to 12 volts in previous posts. DewCatTea Bob has posted a lot of good information about this very subject.

There has been a longstanding plan to consolidate all the electrical posts and arrange them in a sensible order, well structured, as well as to elaborate where deficiencies are noted and to use common terms throughout.

The effort is a collaborative one, but I have been nervous that too many collaborators could lead it to ruin or create disharmony amongst the valued contributors.

Unfortunately I sort of dropped the ball on this effort. I got a side job that consumed most all of my time last November and I failed to keep the contributors motivated and do my share of the work.

I would suggest you search previous posts for the 12-volt conversion threads and expand upon them with your questions.

If you want you can look at the electrical page in progress here:

https://docs.google.com/document/d/1aes ... y=CNzfwfwM


Here is an excerpt from the document under development regarding the question of conversion:


Converting from 6-volts to 12-volts:


The back-story...


The conversion to 12 volts is a purely individual choice. Originality, functionality and reliability are all considerations for the Ducati single owner. The switch to 12-volts is usually predicated by these common desires:


Brighter lighting

Electronic ignition

Electrical system reliability

Electrical component availability



Many people associate the conversion to 12-volts as gaining a more powerful electrical system which in almost all cases is true. But just to be fair let’s review electrical power. It’s not that 6-volt systems are any less powerful than 12-volt systems, that’s a common misconception. Power, which is measured in a unit called “watts”, is defined as the product of Voltage (in Volts) multiplied by Current (in Amps.) A 60 watt 6-volt alternator is capable then of supplying 10 amps (6-volts x 10 amps = 60 watts.). A 12-volt alternator that supplies 5 amps also delivers 60 watts (12-volts x 5 amps = 60 watts.) In this comparison both the 12-volt and the 6-volt alternator are equally powerful.



Ducati supplied motorcycles with 40 and 60 watt alternators in a 6-volt configuration which were sufficient to the task of supplying the needs of the motorcycle as they were outfitted from the factory.. Keep in mind though that the headlights which are the major consumer of electrical power on a Ducati single were on the order of 25 watt units which are not bright by modern standards. If you desire brighter lighting you need to install either a more powerful (more wattage) headlight beam or a more efficient headlamp beam (same wattage but brighter light.)



Given a stock 6-volt system you could try to find a 25-watt Halogen beam which is a more efficient technology and emits more light than incandescent beams for the same amount of power. But finding 6-volt incandescent replacement beams is difficult enough, much less trying to locate a halogen light bulb that fits the headlight bucket perfectly. Also, neither incandescent or halogen 25 watt bulbs will supply anywhere near the light output of any type of 50 watt or better light bulb.



The more common solution then is to install a modern 12-volt sealed beam of around 55 to 60 watts (either incandescent or Halogen.) The problem however is that you need both 12-volts to power the headlight and also more electrical power (watts) than the motorcycle’s alternator in stock form can generate.



You might ask why you can not put a 55-watt beam on a Ducati single with a stock 60-watt alternator. The reason is that there are other electrical consumers (also known as 'loads') on your motorcycle’s electrical system that also want a portion of that limited available electrical power, such as the brake/running light and the ignition system. So the full alternator power output is not completely at the headlight’s disposal. Also you would need to find either a 6-volt 55-watt beam or convert your 60-watt alternator to 12-volts.



A power increase results from either putting in a more powerful alternator or in some cases recovering power from the existing alternator that may be wasted (see “How to capture more power from twin wire lead alternators” elsewhere in this guide.) So in effect more power is gained by:



1) changing to a new alternator that supplies more voltage without sacrificing amperage,

2) changing to a new alternator that supplies more amperage at the same voltage,

3) changing to an new alternator that supplies both more (higher) voltage and more amperage, or

4) modifying the existing alternator (if possible) to supply more amperage (similar to list item number 2.)



Item number 3 will be ignored here as it is covered in the section “How to capture more power from twin lead alternators” and this discussion is about converting from a 6-volt system to a 12-volt electrical system.



A 12-volt conversion requires that all the electrical loads such as the headlamp bulb, taillight bulb, horn, coil, regulator/rectifier and instrument bulbs be replaced from 6-volt units to 12-volt units. The wires and switches can stay the same. Any fuses in the system will have to be re-evaluated as to its amperage rating.



A 12-volt conversion offers more options with regards to commercially available electronic ignition systems, though a commercial 6-volt electronic system is available.



The next question might be “how much power do I need?” The answer is to create a simple power budget that will detail how much power you are likely to require. Here is an example:



1) Headlight: est. 55 watts

2) Brake/running lamps est. 7 to 10 watts

3 Turn signals: est. 3 watts, intermittent consumption.

4) Ignition system est. 10 watts, depends heavily on the ignition system

5) Horn: est. 5 watts, though rarely ever consuming power.

6) Accessories (heated grips, heated vest, GPS system, etc.): On a Ducati single??? Get real!

7) battery charging: This should be negligible in a healthy electrical system.



In this example about a 75 watt alternator is minimally needed, and a 100-watt alternator would be robust.



The alternator produces watts of power, and all the electrical loads of the bike consume watts of power. So at the end of the day the alternator has to outproduce (in wattage) all the wattage of your motorcycle's electrical loads combined.



[Have you ever noticed a light bulb go dim when you switch something else on, and then the light bulb regains brightness when that switch is returned to the off position? This happens because the power source is being asked to deliver more wattage than all the combined loads are asking for. Turning the switch off removes a portion of the combined loads and the power source is better able to supply the demands of the remaining loads including the light bulb.]



Your two choices then are to install a 12-volt alternator or modify you existing 6-volt alternator to produce 12-volts.



Regarding alternator conversions: Keep in mind though that owing to the laws of physics your 6-volt 40-watt alternator will by default remain a 40-watt alternator at 12-volts. Instead of supplying 6-volts DC at 10 amps it will supply 12-volts DC at 5-amps unless you have an rectifier that only captures half the power of the alternator’s sine wave. If your system has no rectifier (an AC system) there is no way to convert to 12-volts and all the power generated is already being used.

Jim

[MotoMike]

For me, once I had my 450 up and running, I found that the lighting afforded by the 6 volt sealed beam to be adequit for the little night riding I did. If I was going to be pushing the envelope, I'd want more light, but as it is, with a functioning system, I saw no reason to make the swap. If I was going to try to use a modern tach I'd be inclined to switch.

[JimF]

I left my Mach 1 as a 6-volt bike as bone-stock originality was my goal.

However, the 450 Desmo was a non-original cafe bike project so I bought a 12-volt alternator so as to be able to run a Lucas RITA ignition system and make kick-starting it easier.

[DewCatTea-Bob]

By: 3564cam...

" would you keep them as 6 volt or shall I convert them to 12 volt.

____ Well Steve, unless you intend to also increase your electrical-system's load/drain (such as using a considerably more powerful headlight), there's little reason to bother with all the voltage conversion-processes, because all the Duc.single-models were pretty-much well balanced quite well enough under normal/regular riding conditions !
Therefore you ought to have some particular circumstance which motivates yourself to bother to complete such a switch-over.


" Your advice on any other things you would recommend like more powerfull alternators would be appreciated. "

____ There's really no good reason to replace the stock alternator just to install another-one that's made to produce more power-output... Because the stock-alternator can be reconnected to alternate means for AC to DC conversion, so as to get up to double the stock power-output (for either 6 or 12 volt systems) !
And unless you intend to have your engine running constantly under 3k-RPM with lights always left on, then there really ought not be any need for any further increased electrical-power.
__ Back when I-myself wanted extra power-juice production, it was pretty-much just intended for helping to run an additional headlight,, but these-days, ya can get extra-low power-consuming LED-type lights which draw next to no power-juice and thus do-not add (relatively) much of any noteworthy power-drain to-speak-of, to the electrical-system's total-load.
__ Do you actually expect to add any kind of extra load to your otherwise stock electrical-system ?


DUKE-Cheers,
-Bob

[Jordan]

However, the 450 Desmo was a non-original cafe bike project so I bought a 12-volt alternator so as to be able to run a Lucas RITA ignition system and make kick-starting it easier.

Didn't all 450 Desmos come with elec ign?

Jordan

[DewCatTea-Bob]

" Didn't all 450 Desmos come with elec ign? "

____ Whatever gave you that notion, Jordan ? ...
I don't know of any DESMO-model which came stock with anything other than a points-type ign.system.
Certainly the pre-1973 450 Mark-3 & R/T DESMO-models never came factory-stock with any kind of electronic ignition-system !


Dukaddy-Dukes,
-Bob

[Jon Pegler]

I seem to remember that most of the late Ducati singles that were sold here in the UK in about 1973 or 1974 were always fitted with electronic ignition as standard.
Many of the 250's and 350's came with the Motoplat system, as their motors were built in Spain, whereas the 450's usually came with the Ducati Electronica system.

I have a 350 with the Motoplat ignition and a 450 with the Ducati, both as originally supplied by the dealer back in 1974.

the Motoplat ignition was always considered to be slightly inferior to the Ducati, although many people racing TZ Yamahas utilise the Motoplat coils etc. with no problems so it can't be that bad.

As regards the choice of 6 or 12 volt electrical systems, I personally like to go for 12 volt, but as Bob says, it rather depends what you intend to use the machine for and how much night riding you're going to do.

Many of the late Mototrans singles came with 12 volt electrics as standard (Usually with points ignition rather than electronic ignition)

12 volt systems do have a greater choice of bulbs/ LED's that are easier to buy at your local store.

[Jordan]

" Didn't all 450 Desmos come with elec ign? "

____ Whatever gave you that notion, Jordan ? ...

Just a guess - I'm not a good historian.

Jordan

[3564cam]

thanks guys really usefull.I dont intend to do much night riding at all but here in the UK it's good practice to run with the headlamp on even during the day so as to stop numpty car drivers taking you out at junctions.
Is there a electronic ignition system available in 6 volt?i am sure it will help starting the 450!
Steve