Re: 12V DC CONVERSION - HOW TO

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byron
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Sun Feb 13, 2011 12:21 am

This is intended as a guide to converting an electronic 12v Lambretta to DC.
So it assumes that the scooter is fitted with a typical stator, flywheel, CDI, regulator kit.
___________________________________________________________________________
Parts needed :
  • Single phase rectifier [eg the Wassell units as mentioned in other threads]
    12v battery [4.5 Ah is ample for “standard” lights]
    Fuse & fuse holder
    DC horn
    terminals, cable, sleeving etc
___________________________________________________________________________
Remove the stator
Make a mark to enable it to be refitted in the same position, which should retain your existing ignition timing.

Modify the stator
Each end of the coils on the stator needs to be connected to the rectifier.
So the existing earth tag should be removed, and an additional wire added.
Image
Unsolder the wire as indicated above, and solder a new wire to the end of the coil windings. Use heatshrink to insulate this from the stator plate.
Image
Feed this new wire though the plate to join the other wires. Sleeve the cables from the stator.

Refit the stator
Make sure the wires are not trapped or likely to snag on anything. The cables to the CDI can now be reconnected.
Image

Fit the rectifier
Next, work out how long you need the leads from the rectifier to be, then cut, sleeve and add terminals.
Remove the old regulator unit, and fit the new rectifier [as the mounting spaces are different, new mounting holes may need to be made], earthing the black to one of the fixing points.
Image

Connect the wires
Connect the wire from the stator that went to the regulator* to one of the yellow leads on the rectifier; and the new wire you just fitted on the stator to the other yellow. It doesn’t matter which way round these are.

*This wire was brown on the stator we were doing, but could be yellow [or something else...] on another stator; two stators can even have the same colour wire doing a different job ~ always check what the wire is actually connected to rather than relying on the colour of the insulation

The cable[s] that did go to the output side of the regulator is[are] connected to the red lead from the rectifier. The +ve side of the battery should also be connected here. Doing it this way will mean that in the event of the battery losing its charge the lights will still work when the engine is running.
Image

Fit a fuse
A fuse should also be fitted either in this +ve lead to the battery, or on the –ve earth side of the battery. If it is fitted on the +ve side, do it after the feed into the loom, as again this will ensure that the lights still work if the fuse blows [although of course the cause of the fuse blowing should be traced and fixed as soon as you can].

Fit the battery
Make sure the battery is secure and that the +ve terminal cannot short out on anything.

Tidy the wire routing
Allow for any moving parts and securely neatly with cable ties.

Replace the horn
Worth inspecting the terminals here too and changing if necessary.

It may also be worthwhile checking your ignition timing with a strobe again.
___________________________________________________________________________

A simple diagram of the conversion :
Image
___________________________________________________________________________

Use decent terminals, insulation and heatshrink throughout.

This conversion will not be sufficient to run extra lights etc for any length of time; if Pathfinders for example are to be used then ideally the stator should be rewound, or the standard lights could be run off the AC using a Vespa type 5-pin rectifier, but that’s beyond the scope of this article. Relays would also be needed if the current is increased to this extent.
___________________________________________________________________________

The scooter we did this conversion on today had an Indian stator, with BGM LED rear lamp, LED sidelights and standard bayonet fitting 35/35w halogen headlamp bulb. A 7.2Ah battery was fitted.

Without the engine running the draw with all lights on was 2.4A; the current on the battery became positive at around 2100 rpm. So this means at fairly low revs the battery is getting more than it is being required to supply. Therefore there should be no problems with the battery draining if all the lights are used.

We fitted a Readspeed bulb; this raised it to 2.8A and needed 2300rpm to get a positive current reading on the battery, but the light did seem much better. And again, perfectly adequate for keeping the battery charged whilst riding with all lights on.


Thanks to CraigH for the use of his bike for photos etc

This piece is meant to be written as a simple guide to converting a typical Lambretta to DC; please comment if it is unclear or I have missed out any steps.
Hopefully it will be useful for what should be fairly representative of many people’s needs.


Jarv
Last edited by byron on Sun Feb 13, 2011 2:12 pm, edited 3 times in total.

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soulsurfer
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Sun Feb 13, 2011 8:29 am

^^^ Looks good Jarv ;-)
Sorry I've not had much input on this, had other stuff on my plate, but I'd like to give a special mention to Sam Cobb, sam_c - Flaxton Flyer, and Kev - firekdp, for their help in the early stages of this getting conversion of the ground a couple of years ago, as without their help, I probably would have given up back then. :D
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mark
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Sun Feb 13, 2011 9:39 am

Reads perfect mate :) p

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byron
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Sun Feb 13, 2011 10:11 am

soulsurfer wrote:...a special mention to Sam Cobb, sam_c - Flaxton Flyer
yes, indeed, I was trying to remember who it was that first wrote about their podtronics experiments. It's what got me starting to think about all this, as well as your work.
And of course firekdp is the man who understands it all

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byron
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Sun Feb 13, 2011 11:43 am

following a post on LCGB, just edited the guide to highlight that not all stators have the same colour wires, and different stators can even have the same colour doing different things...
So always check what the wire is actually connected to rather than relying on the colour of the insulation...

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RICSPEED
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Sun Feb 13, 2011 12:54 pm

EXAMPLE OF DC LOOM

Image
DC wiring by mark & anne's photos, on Flickr
courtesy of soulsurfer (of lcgb)
you don't need to run the battery if you don't want ;)
using this rectifier

i have not purchased of this ebayer its just an example of the unit we use

by mark



EXAMPLE OF DC LOOM WITH RELAYS FOR SPOT LAMPS


Image

the reason i run relays on my series 1 is that the light switch will only allow 5 amps approx to go thru without getting very hot, so we decided that relays are the way to go.
i thought that you should know this a 2 rallymasters and a 60/55 halogen headlight will get the switch very hot, just a headlight will not need relays tho

by mark
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byron
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Sun Feb 13, 2011 12:55 pm

byron wrote:
soulsurfer wrote:...a special mention to Sam Cobb, sam_c - Flaxton Flyer
yes, indeed, I was trying to remember who it was that first wrote about their podtronics experiments. It's what got me starting to think about all this, as well as your work.
And of course firekdp is the man who understands it all
yes, and of course, mark ~ tidd ~ pride, with his constant Go DC! campaigning :lol:

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soulsurfer
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Sun Feb 13, 2011 12:57 pm

byron wrote:
byron wrote:
soulsurfer wrote:...a special mention to Sam Cobb, sam_c - Flaxton Flyer
yes, indeed, I was trying to remember who it was that first wrote about their podtronics experiments. It's what got me starting to think about all this, as well as your work.
And of course firekdp is the man who understands it all
yes, and of course, mark ~ tidd ~ pride, with his constant Go DC! campaigning :lol:
;)

It's like the Oscars 'round 'ere :lol:
Last edited by soulsurfer on Sun Feb 13, 2011 12:59 pm, edited 1 time in total.
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RICSPEED
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Sun Feb 13, 2011 12:59 pm

fantastic lads that's great and thanks Byron for the wright up :D

ps ...cleaned up the thread but reposted marks diagrams for reference
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Sun Feb 13, 2011 2:18 pm

thats a good conversion,can you be more specific what the regulator is off?
regards
joe

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