R-R for 12 Volt conversion

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ducwiz
Posts: 439
Joined: Tue May 22, 2012 12:52 pm
Location: near Frankfurt, Germany

R-R for 12 Volt conversion

Postby ducwiz » Sun Nov 17, 2019 12:30 pm

Hi,

from time to time threads about converting the nasty 6V electrics into a 12V version. Therein some chinese R-R's are often mentioned. Here is my recommendation: This https://www.ebay.com/itm/223467332827 is the cheapest R_R for a conversion to 12 Volt I could find on ebay. It can be used with the alternators of all w/c singles (points or CDI), and after a slight mofification of the stator on the n/c singles with the 60Wat alternator.
Important: if you find a different seller, his R-R must have 5 wires and the same sequence of wire colors as depicted in the ebay offer. Exception: the pink or orange wire may also be yellow, like https://www.rexs-speedshop.com/product/universal-single-phase-regulator-rectifier-110w/.

cheers Hans

Jordan
Posts: 1010
Joined: Fri Dec 24, 2010 11:29 am

Re: R-R for 12 Volt conversion

Postby Jordan » Mon Nov 18, 2019 2:48 am

Hi Hans,
What are the 5 wires connected to?

ducwiz
Posts: 439
Joined: Tue May 22, 2012 12:52 pm
Location: near Frankfurt, Germany

Re: R-R for 12 Volt conversion

Postby ducwiz » Mon Nov 18, 2019 6:45 pm

green = battery -/(chassis ground)
red = battery + (red)
yellow = AC in (yellow from alternator)
pink or orange = AC in (yellow from alternator)
black = battery + from ignition switch (on w/c models: brown wire)

Full Wave Regulator schematic 2.jpg


Some of the R-Rs vave two yellow wires, both AC from alternator (see the one from Rex's speedshop).

Hans

Jordan
Posts: 1010
Joined: Fri Dec 24, 2010 11:29 am

Re: R-R for 12 Volt conversion

Postby Jordan » Mon Nov 18, 2019 9:27 pm

Thanks Hans.

I was puzzled by the need for a 5th wire.
I see now the purpose is to isolate the battery from the charging circuit, otherwise because of the circuit design there would be a current leak when the engine is turned off, that would eventually flatten the battery.
I guess it's the price you pay (not much - just one extra wire to attach to the ignition switch) with the more complex and efficient regulator designs using SCRs.
Having been brought up with the bare bones Lucas zener diode type regulators, I must say that despite those being apparently crude, I do like the minimal requirement for wiring connections, and any inefficiency isn't noticeable.

But these rec/regs you've told us about are so cheap - I am buying some for stock.
I hope they're not filled with sand!

Johnnie Mototrans
Posts: 13
Joined: Tue Oct 29, 2019 1:35 am

Re: R-R for 12 Volt conversion

Postby Johnnie Mototrans » Mon Nov 18, 2019 9:36 pm

Thanks Hans
Cheap regulator rectifier ordered along with what I hope is a suitable coil and ht lead.
£30 All in.
Who said Ducati ownership had to be expensive.
Johnnie

Dan C
Posts: 35
Joined: Wed Feb 12, 2020 12:52 am
Location: Armidale, NSW, Australia

Re: R-R for 12 Volt conversion

Postby Dan C » Thu Feb 13, 2020 7:00 am

Hi Hans,
I'm a new member and I have been reading your electrical advice, and that of others, with much interest. I have learnt a lot and really appreciate the sensible advice everyone gives. After considering what everyone says, my current usage, and the cost, I am happy to retain 6 volts (1974 450 desmo).
So my two queries are;

1. Is there a comparable cheap 6v RR available on Ebay (ie the 6volt equivalent of the 12volt one you provided a link to at the beginning of this post). If so could you please provide a link?

2. In the text of Mick Walkers Ducati Singles book he quotes the widecase alternator output as 80 watts (on page 101). Later in the specifications section its given as 70 watts (pp 165 & 173). In some of your posts you are quoting 90 watts. I'm suspecting the answer is that they are all correct - it just depends on the rpm, but I'd be interested in your comments. Obviously if 90 watts are reliably available at low rpm it makes a significant difference in the potential headlight wattage.

Cheers
Dan

ducwiz
Posts: 439
Joined: Tue May 22, 2012 12:52 pm
Location: near Frankfurt, Germany

Re: R-R for 12 Volt conversion

Postby ducwiz » Thu Feb 13, 2020 11:52 am

Dan,

afaik there is no cheap (chinese) 6V R-R available on ebay or elsewhere. The reason is:
Ducati used a 2-phase (or dual-halfwave) system with their 6V alternators in the w/c singles, resulting in 3 alternator wires (2xyellow, 1xred). This principle is nearly unique, only the spanish SAPRISA company made such 12Volt alternators and R-Rs for Moto Guzzi big and small block models, in the 80ies and 90ies. So, if you choose to stay with 6 Volt, you are bound to the original R-R, or replicas thereof:

https://www.ebay.co.uk/itm/Regulator-Voltage-6V-14A-Ducati-Scrambler-250-350-450-/362455952900?&shqty=1&isGTR=1#shId
https://www.ebay.com/itm/179606-REGOLATORE-DI-TENSIONE-DUCATI-SCRAMBLER-350-450-1972-1973-1974-/391036624232
https://www.ebay.com/itm/REGULATOR-DUCATI-450-cc-MARK-3D-SCRAMBLER-/254186131121
http://www.guzzino.com/rerethph6v.html

The 12 Volt conversion of the w/c charging system omits the red wire, hence running in full-wave or single phase mode, at a doubled AC voltage. For this system there are a lot of chinese R-Rs available, with 5 (or 4) wire connections available. A few for 6 Volt are rarely offered, maybe for older chinese scooters or mopeds, but they also are made for single phase operation. If you use one of these, you might be able to limit your system voltage to ~7 Volt, but loose roughly 50% of alternator power. I do not recommend doing so ...

My information about the output power for the w/c alternators (from different owner's manuals):
The 6-coil stator used in the bikes with points ignition delivers 90W max.
The 5+1 coil stator puts out only 75W, because one coil is differently wound and separately connected to power the electronic CDI ignition box.
So there is alway 75W available for the electric loads, the type of stator i. e. ignition does not matter. But, if you swap the electronic pickup against a point and AAU set and run the CDI alternator with points ignition, you sacrifice ~15W by idling the CDI supply coil.

Maybe you should rethink your decision against a 12V modification (which offers a lot of advantages).

cheers Hans

p.s. can you please post your location (US, EU, etc.?)
Last edited by ducwiz on Thu Feb 13, 2020 12:13 pm, edited 2 times in total.

ducwiz
Posts: 439
Joined: Tue May 22, 2012 12:52 pm
Location: near Frankfurt, Germany

Re: R-R for 12 Volt conversion

Postby ducwiz » Thu Feb 13, 2020 11:55 am

Johnnie Mototrans wrote:Thanks Hans
Cheap regulator rectifier ordered along with what I hope is a suitable coil and ht lead.
£30 All in.
Who said Ducati ownership had to be expensive.
Johnnie


Hi Johnnie,

can you report any results of your conversion?

Hans

ranton_rambler
Posts: 281
Joined: Sun Jun 04, 2017 11:33 am
Location: Stafford UK

Re: R-R for 12 Volt conversion

Postby ranton_rambler » Thu Feb 13, 2020 7:37 pm

The Electrex R-R can be configured for either 6V or 12V by cutting a link wire. Mine is set to 12V, but with the 2 wire alternator.
Works well enough for me. I don’t ride the little Ducati much at night but have an LED headlamp bulb to reduce demand.
Ian

Dan C
Posts: 35
Joined: Wed Feb 12, 2020 12:52 am
Location: Armidale, NSW, Australia

Re: R-R for 12 Volt conversion

Postby Dan C » Fri Feb 14, 2020 7:02 am

Hi Hans,

Thanks for clearing that up, very much appreciated. I've already received a new 6v ignition so its too late to change for the time being anyway.
However there are some other singles in the shed waiting for some attention so I guess that's they way I'll go with them when the time comes....
I've added location in my profile so it should show up. Armidale NSW Australia.

Cheers
Dan


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