Forum

[Adrian]

Here's one for the electrics experts, and it concerns the alternator stator used on some home market 350s (early AVL 350 Machismo and Thunderbird. Here's the beastie in question.







Of the 6 coils, one is a completely separate CDI charging coil, which leaves the other five for power, with three(?) coils to power the headlight via an AC regulator and two(?) coils for the reg/rectifier for battery power (side, stop, tail and speedo lights, indicators and horn). The red and the black wires correspond to the two purple wires on some four wire alternators, the yellow and amber (orange) wires are for the AC headlight.



MY QUESTION is as follows.



Is it possible to re-wire the output from the five power coils so that the whole lot can just go the the reg/rectifier unit as on (e.g.) a Lucas RM21 alternator? I know according to the Snidal manaual the two sets of coils on a FOUR wire alternator can both be fed into the same reg/rectifier, but I'm not so sure if this is possible with the three + two coils arrangement here. Assuming it IS possible I'm guessing it would be neater to resolder the connections to the coils and have only two power wires coming out of the chaincase.



Ta very much.



A.

[Alan R]

Hi ADRIAN.
OK------I'll take the first stab at this one}--- In terms of energy output, each coil assembly is rated at 12v ( as it's a 12v system ) and "X" amps output at any given rpm ( Remember, the faster the rotor turns the more current is produced )...and all this output will be in AC form.........So from this description alone you must}--a) Connect all coils in PARALLEL ( to maintain the 12v ).... and b) Feed this total output into a Rectifier/Regulator assembly....... The rectifier will change AC into DC whilst the Regulator will limit the total output to around 13 - 14 volts...
I think that makes sense ??------ E-Lec-Trickery !!! --------- Now comes the repost, I fear..

[binary]

I think that Alan R may have the answer. If each coil only charges 12 volts then you should be able to connect them in parallel so that combined they only deliver 12 volts AC to the rectifier to be converted to 12 volts DC. You must be going to run your headlight from the battery now and have decided to use all the coils to charge it. Perhaps these coils do not act like a battery where with batteries you can hook multiples up to give the same voltage. Perhaps they will just multiply the voltage, but if that is the case then the 2 coils for battery power would give a 24 volt feed into the rectifier, and the 3 coils for the headlight would be putting out 36 volts AC which without a regulator would blow the 12 volt headlight bulb. If you check the voltage produced before being regulated and it is 12 volts for say the headlights 3 coils then they must be wired up parallel at the alternator, and you should be able to wire all the coils the same way to give 12 volts AC at the alternator. Check the red and green wires on the CDI charging coil as these are not soldered on very well, as they come from India, and the wires them selves are of poor quality copper being very brittle and easy to break inside there insulation. I found it necessary to have my own western quality wires soldered onto this coil. You do not want to have to go back into the primary case just to mend one of these wires that may have broken. Please let us know how you go with this and post it up as it would be interesting to see what you find out.

[Adrian]

Thank you gentlemen.



The plan is for the bike to run completely battery-less as the ignition and headlamp or already directly powered from the alternator, I'm just not sure of the coils normally reserved for the charging system would manage to power the indicators, horn stop/tail and speedometer lights without a battery in reserve. The plan is to use LEDs throughout, including the headlamp, though LED headlamp bulb replacements can't run on AC.



Obviously it's cheaper if I can run all the power coils through one capacitor-fitted regulator/rectifier instead of having to fit a second one for the headlamp supply as well.



Binary, I take the point about the CDI coil wiring, it's not great, and re-soldering the connections with some decent quality wire sounds like a wise move.



A.

[Barry_Q]

Be careful folks. Rewiring all of the coils in parallel may not be a good idea. Until you know the rating of the alternator in Watts, you won't be able to wire the coils to match the load of the bulbs, etc. For example: A D1 bantam had a flywheel magneto rated at 45 Watts. It had 3 coils. Each coil was 15 Watts. The 25 Watt headlight bulb is added to the 5 Watt tail light bulb. This gives 30 Watts. Therefore; 2 coils are wired in series. The 3rd 15 Watt coil was used to drive the brake light bulb.

[Tim NZ]

Yes, it is possible to reconfigure the stator windings to run similar to the RM19/21: Confirmation will be needed as to Series or Parallel coils?
The Stator is perfectly capable of cranking out well in excess of 30v...


Regulation has to be able to cope with in excess of 120w: 10 amp ~ 30 amp surge


Attempting to run the total output through the OEM regulator will not be very successful unless the bike is run with Head light on at all time. OR has a manual Stator-coil switching arrangement similar to that as fitted to the 6 v bikes, and those with emg start provision. So as to regulate magnet flux and restrict output...


The OEM 2 pce single phase regulator unit was never designed or intended to cope with total alternator output.

[Adrian]

Hi Tim,



the electrics will be a custom-wired system and OEM reg/rectifiers are NOT part of the plan, more like the Sparx 023 with the built-in capacitor, which IS designed to handle 120W alternators. A similar sort of thing to the boyer Powerbox that our hosts sell.



http://www.tri-corengland.com/acatalog/ ... ml#SID=122



A.

[Alan R]

Hi Guys--------- just to clarify a point.. I didn't mean that you'd have to join ALL the coils together in one go in parallel....just that when you do join any coils together then it must be in parallel to maintain the 12v rating of the system overall.......Joining any in series will naturally give "X" No. of coils multiplied by 12v....