R-R for 12 Volt conversion

[Jordan]

If a single phase regulator can be easily adjusted to work at either 6V or 12V, that must mean the alternator is set to work as if for 12V, by not connecting the centre tap wire to anything.
Would there then not be a loss of current output, due to the required doubling of the working length of wires when this is done, then run as a 6V system?

[ranton_rambler]

If a single phase regulator can be easily adjusted to work at either 6V or 12V, that must mean the alternator is set to work as if for 12V, by not connecting the centre tap wire to anything.
Would there then not be a loss of current output, due to the required doubling of the working length of wires when this is done, then run as a 6V system?

My bike has a 2 coil/2 wire alternator. It seemed that the 2 coils were joined at a common ground between them so I unsoldered it and insulated as per advice from here and elsewhere.
The Electrex reg-rec is made specifically for Ducati singles and has a link wire. Leave as-is for 6V, cut for 12V.
I’m not an electrical engineer but I believe original system would have been half-wave rectified but is now full-wave.
Anyway, seems to work and keeps battery charged and lights working.
Ian

[Scottish888]

Here is the link for the same item from Ebay UK

https://www.ebay.co.uk/itm/5-Wires-12V- ... Swe0tca5Gz

Just ordered one, thank you

[ducwiz]

If a single phase regulator can be easily adjusted to work at either 6V or 12V, that must mean the alternator is set to work as if for 12V, by not connecting the centre tap wire to anything.
Would there then not be a loss of current output, due to the required doubling of the working length of wires when this is done, then run as a 6V system?

My bike has a 2 coil/2 wire alternator. It seemed that the 2 coils were joined at a common ground between them so I unsoldered it and insulated as per advice from here and elsewhere.
The Electrex reg-rec is made specifically for Ducati singles and has a link wire. Leave as-is for 6V, cut for 12V.
I’m not an electrical engineer but I believe original system would have been half-wave rectified but is now full-wave.
Anyway, seems to work and keeps battery charged and lights working.
Ian

Ian,

you are right, the difference between 6 and 12 V operation is indeed half-wave, and respectively full-wave rectification. Page 173 from the Pantah manual explains the difference.

page173.jpg

I presume, this is the R-R mentioned above: https://www.electrexworld.co.uk/acatalog/RR02.html#SID=439
Electrex describes it as a "single phase regulator", indifferent of 6 or 12 V operation. Unfortunately, they also give no electrical schematics (which must be different for 6 or 12 V connection). For me, this regulator is not the optimal 6V solution for the Ducati 2phase 6V alternator. I have never tested this, but it should be necessary to run both half-windings in parallel. Only this will give the maximum power output. But: as the two windings run in opposite (180°) phase angle, one has to split the common connection point and revert the ends of one of the windings, then connect them in parallel - otherwise no output power will appear.
Your 450D alternator had a common ground connection? This is very strange, as the common terminal originally is connected directly to battery+ ! This ground connection scheme was exclusively used in the Mach1 and other models with the 60W 6-yoke/4-coil alternator, together with the huge and heavy "black brik" R-R. Which R-R did you use?

Hans

[Duccout]

When I bought my 750 Sport bevel, way back in 1975, the alternator was marginal in its ability to keep the battery charged when running the lights. John Carpenter of Mistral Engineering solved the problem by fitting a Lucas zener diode and rectifier, allowing the alternator to run at full output all the time. The alternator had three wires coming from it, two output wires which john connected to the rectifier, and one wire connected to a single coil which simply provided power to the regulator; this was left unconnected.

[Scottish888]

It looks like my 74 250 widecase should be able to convert to 12v with the new R/R and connecting the wiring as suggested.
No need to open the case and do any connections at the stator?
Pic is the stator on my bike.

LH case stator in_edited.jpg

[ducwiz]

This is the DUCATI stator for a CDI. A single coil (located at "3 PM") produces 3-400 V AC for the ignition box, while the remaining 5 are connected in a 2 phase-fashion (2x yellow wire, 1x red as the common connection of the two winding branches) for 6V power. The alternator delivers 6 V/75 W maximum. It can be converted to 12 V the same way as the 6-coil/90 W alternator mounted with the points ignition.
Do you still run the CDI? If you have converted from CDI to points, the HV winding idles, and the power (~15 W) for the points/coil system is taken from the remaining 75 W. In turn, the battery might be charged insufficiently, especially in a 450 due to the lower average angine rpm's.

cheers Hans

[Scottish888]

Hi Hans,

The bike still has the original Ducati electronic ignition and it works well.
If it is easy enough I would like to convert it to 12 volts, is it just a matter of hooking up the new regulator/rectifier to replace the Ducati system? (shown in attachment)
Regards.

D_edited.jpg

[ducwiz]

The conversion is very easy. Just connect the two yellow wires from your alternator with the yellow and pink wires of your chinese R-R. Connect the green R-R wire to battery -/chassis ground, the red wire to your battery + ( a loating fuse rated 8 A put in between is recommended). Finally, the black R-R wire must be connected to the brown one formerly hooked to "marrone" on the Logitron R-R.
https://www.rexs-speedshop.com/wp-content/uploads/2018/09/single_phase_regulator_12volt_ml-799x568.jpg Use this picture for reference.
Important: do not connect the red wire from the alternator anywhere, but isolate the end terminal with care and stash it away safely. And mount the new R-R upside down below the mounting bracket, so that it's cooling fins are exposed to the streaming air.

Hans

[ranton_rambler]

I’ve got the RR163 on my bike. Electrex make a whole range of units so best to speak to them before ordering. If you can past the woman that answers the phone, they are very helpful.
Ian