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BSA B40 1961 6Volts to 12Volt conversion Help #630581
12/18/15 5:58 am
12/18/15 5:58 am
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Carlos Offline OP
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Bad news.

I was able to put the bike running at 12V, but because i was using a battery. (4ohms 12V coil, SH638-12 regulator/rectifier, stator connected to full output)
I have check with ammeter and voltmeter, and Bike does not charge battery frown
Draws 3A to 4A when running without lights on, and about 6.5A with lights on.
Regulator/retifier seems well connected (SH638-12)

I removed the battery and inserted the capacitor instead.
There is no spark in spark-plug.
I Checked the voltage at capacitor, and i only have DC 3V "spikes" when kicking bike. It is to low to coil create a spark!

So i turned my self to the stator again.
Before someone asks..yes i had the shunt between "GY" and "DG" stator wires.
I Removed everything (all wires) and checked each coil.
Light bulb test was ok. (test to heck each pair of coils)
I connected the old rectifier to one pair (WG-GY) and got 3.5V with foot kicking, then made the same thing to the other (WG-GB), and got the same 3.5V DC with foot kick.

I then inserted the shunt between GY-GB. Inserted the rectifier and got only 2.9V DC with foot kick. even Lower output?
Again too low for the coil produce a spark.

I found the number in stator:


What else can i do? the stator as too low output for 12V conversion?
Is this low voltage expected but i am doing something wrong?


Kind regards
Carlos

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Re: BSA B40 1961 6Volts to 12Volt conversion Help [Re: Carlos] #630583
12/18/15 6:37 am
12/18/15 6:37 am
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kommando Online content
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What is the magnetism in your rotor like, if you try and pick it up by placing a large screwdriver on the top of a magnet can you lift the rotor? If it drops off its too weak and you need a new one as it lowers the alternator output too much. If its the smaller diameter one I don't know if spares are available.

Re: BSA B40 1961 6Volts to 12Volt conversion Help [Re: kommando] #630587
12/18/15 9:03 am
12/18/15 9:03 am
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Carlos Offline OP
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Hi Kommando,

Magnetism seems fine. I done that test previously when i had the 6V trouble.(on the other thread)

Rotor is the 74mm version.

Do you agree that the alternator test i have done, as low voltage?
What voltage should i expect from stator, just by kicking the bike?

Kind regards
Carlos

Re: BSA B40 1961 6Volts to 12Volt conversion Help [Re: Carlos] #630608
12/18/15 12:00 pm
12/18/15 12:00 pm
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kommando Online content
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Not an expert but 3V seems too low, I have an Voltage LED on my B44 and using only the capacitor (battery disconnected at fuse) I can kick the bike the bike over and the LED glows showing at least 10V, plus I can get a spark from a Digital Boyer which will start the bike.

Re: BSA B40 1961 6Volts to 12Volt conversion Help [Re: kommando] #630634
12/18/15 2:40 pm
12/18/15 2:40 pm
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quinten Offline
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At this point you have too many variables to know which is bad .
Is it the stator ? , the regulator ? or the wires between the two ?
I'm not familar with your early stator .
Do all the separate wires in the stators-coils appear to be the same-gauge ?
I believe you said the lead-wires have been replaced ?
And you have a 1ohm dummy load ?

Load test the stator first and separately at 3000~5000 rpms.
Do this by running the bike on battery power only .
Connect your 1ohm load to the 3 possible pairs of stator wires
...To determine which pair gives greatest output .
Under a 1ohm load , Watts = volts × volts
This is your stators gross AC output before rectification .
now With AC watts know , you can plug this pair of wires into any 2 of the 3
Regulator inputs ... put the 1ohm load on dc regulator output ... and test again .

.

Last edited by quinten; 12/18/15 3:09 pm.
Re: BSA B40 1961 6Volts to 12Volt conversion Help [Re: Carlos] #630642
12/18/15 3:30 pm
12/18/15 3:30 pm
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Bolton Lancs UK
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Andy Higham Offline
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Disconnect the regulator/rectifier. Start the engine and measure the AC voltage on each pair of output leads, a healthy alternator should give about 20V to 50V at around 3000 rpm


1955 BSA B31 500cc "Stargazer"
1962 Greeves 200cc "Blue Meanie"
1962/67 Greeves 350
1967 Greeves 360 Challenger
1984 Suzuki GSX1100 EFE "Sorcerers Apprentice"
GM500cc sprint/LSR bike "Deofol"
Jawa 500cc "Llareggub"
2003 Aprilia RSV Mille "Lo Stregone"
Re: BSA B40 1961 6Volts to 12Volt conversion Help [Re: Andy Higham] #630767
12/19/15 2:32 pm
12/19/15 2:32 pm
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Carlos Offline OP
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Thank you all for the reply so far.
Sorry for my bad paint skills. smile

I made this 2 tests:




I am sure rectifier is Ok.
Maybe i have an intermittent bad alternator.

When i fixed the 6V version of the bike (another thread in forum), alternator was charging battery with 1.5A with full lights ON at half throttle.
I remember that i had some good readings versus the testing manual numbers.I was pretty sure, that alternator was healthy frown

How did the bike work at 6V version, but i have 3V DC in alternator (at maximum coil power connection )?
How can the 12V light glow very bright (at maximum coil power connections) just by kicking stater?

I never liked this picture:
Is rotor to far out of stator?


Nut that holds rotor is only secured by 2 threads!!
Clearances from stator to rotor are homogeneous.(around 0,2mm).

Another one:


Again...Maybe i have an intermittent bad alternator?

hellllppppppp
Carlos


Last edited by Carlos; 12/19/15 2:36 pm.
Re: BSA B40 1961 6Volts to 12Volt conversion Help [Re: Carlos] #630937
12/20/15 5:45 pm
12/20/15 5:45 pm
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Hi Carlos,
Start the engine and check the voltage with the bulb conected to the alternator where you got the brightest light kicking (3rd pic)
You should easily get 12v across the bulb at 1500-2000 rpm
The rectifier drops the voltage by approx 0.6v per diode
If the bulb lights up well on AC directly from the alternator it should also light up when connected through the rectifier

Have you checked the winging resistance to earth (frame) as I asked in your other thread?

Digital meters can lead to confusion when working on 6 /12v bikes
mad
The cheaper meters are not "true RMS" and give all kinds of false readings

The rotor nut is not a flat nut but extends inwards through the center of the rotor

John

Re: BSA B40 1961 6Volts to 12Volt conversion Help [Re: chaterlea25] #630991
12/21/15 5:17 am
12/21/15 5:17 am
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Carlos Offline OP
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Hi John,

Thank you for your reply.
Rotor nut is not flat...i would not guess it smile

There is no resistance/connection between frame and coil winding's. I Checked it with a digital meter and with a light bulb.

Quote:
"You should easily get 12v across the bulb at 1500-2000 rpm"


...but i need 12V DC just by kicking engine?
What would be the minimum DC voltage to make a spark in ignition coil?

Like i said, i can make the 12V 40W bulb light fairly bright with just kicking the engine, but i cannot saturate the ignition coil to produce a spark!

Is engine kicking equal to engine running in idle? (regarding max RPM achieved)
If so, i will try to measure the AC and DC voltage at idle (one bulb connected).

The ignition coil it self draws 4A from the battery (thats what i measured...so i assume its the coil consumption), so its seems hard for the alternator to produce 12V 4A just by kicking! Thats almost 80% of the available power for this old stators. would be ok for 3000rpm not foot kicking!

i am lost frown

Carlos

Re: BSA B40 1961 6Volts to 12Volt conversion Help [Re: Carlos] #631000
12/21/15 7:49 am
12/21/15 7:49 am
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argyll. scotland, uk
gavin eisler Online content
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Kicking the engine over is not equal to idle speed. Even at idle speed around 1,000 rpms the alternator will not produce over 12 volts, the revs need to be over 1500- 2000 rpms .


Without a battery the only way the alternator can make enough volts for ignition is with a running bump start.
The battery is very essential for starting with a coil system, kicking speeds do not easily create the voltages required with the alternator alone.
Heres what I would do, disconnect the live from the rectifier to the battery.
Start the bike on battery alone,with the test lamp and voltmeter, run the motor at higher than idle and check voltages/ brightness across the alternator tails, reconnect to rectifier then check rectifier DC output voltage. Volts should rise with revs.

The ignition coil current seems about right V= IR, if V=12 , I = 4 , then R coil resistance ( impedance /reluctance ) is somewhere around 3 ohms, in the ball park, so the 4 amp current draw seems about correct.
At this point I fall back on ( Im just a mechanical engineer with a generation background, some more wised up Electical engineer will be along soon. ( Festive greetings Stuart)


71 Devimead A65 750
56 Norbsa 68 Longstroke A65
Cagiva Raptor 650
MZ TS 250
The poster formerly known as Pod
Re: BSA B40 1961 6Volts to 12Volt conversion Help [Re: gavin eisler] #631055
12/21/15 4:03 pm
12/21/15 4:03 pm
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Hi Carlos,
Stuart is corrrect, you need the battery to get a good low speed spark
In reality with the 12v conversion you need to forget about the EMG
ignition system

Are you using one of the little block rectifiers? or something from another motorcycle?

John

Re: BSA B40 1961 6Volts to 12Volt conversion Help [Re: chaterlea25] #631077
12/21/15 6:28 pm
12/21/15 6:28 pm
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Carlos Offline OP
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Hi everyone,

When i start to read some articles, and got some advise from you guys, you told me to convert to 12V and battery would not be needed. Just a capacitor instead of battery.
So isn't this correct? Now i need battery...i am confused.

I start the conversion using the SH-638-12 rectifier/regulator.
With all wires in place ,the bike started ok and i saw voltage starting to rise in battery (without lights on). I saw voltage going up till 13V, but i didnt wait for the 14.5V to see if regulator was working.
With lights on, i wasn't sure bike was producing enough power (didnt inserted the ammeter)...but i was using 40W head light bulb..maybe to much for the old alternator.

so i moved on, removed battery and insert the capacitor. I never saw more then 3.5V DC when kicking engine. so no spark was produced.

So you are telling me that i need battery? or a 200W stator to be able to get 12V at kicking?

thats bad news that i have to explain to my friend frown

please advice.
kind regards
Carlos

Re: BSA B40 1961 6Volts to 12Volt conversion Help [Re: Carlos] #631079
12/21/15 7:14 pm
12/21/15 7:14 pm
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You may have a bad capacitor, they have a short shelf life, Ive no real experience with them, fine if you dont go out in the dark maybe.The alternator was made 50 years ago , rotor magnetism will be poor so stirring the smoke in wires will need more revs.


71 Devimead A65 750
56 Norbsa 68 Longstroke A65
Cagiva Raptor 650
MZ TS 250
The poster formerly known as Pod
Re: BSA B40 1961 6Volts to 12Volt conversion Help [Re: Carlos] #631158
12/22/15 7:18 am
12/22/15 7:18 am
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Carlos Offline OP
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Thank you all for kind replies

Capacitor is new (bought 2 just in case), and its 4700uf RC 3A, 35V or 50V.(dont recall)
Something like this:


And yes...well conected, minums to minus and positive to chassis.

Quote:
Lots of guys on this site run bikes with just capacitors and regulators so we know the system works .


and i believe it also...but i just dont see any spark!

Quote:
You can use a capacitor and NO battery with a reasonable working 12v alternator.

reasonable alternator is what i dont think i have. I know it produces 10A @ 5000RPM when the bike was 6Volts.
So i think we can say 5A @ 12V @5000RPM.
If we take 2.5A for coil like NickL says, i only have 2.5A for all lights in bike. Seems to low, and we are talking about @5000RPM.
Imagine what i have at idle.

If this should work in 12V...maybe.
With 6Volt bike with lights on, i had 1,5A charging at 3000RPM (25W headlight bulb)

Quote:
Anyway, the regulator you have will start to work at around 14.5v so you need to get the bike running at about 2-3000rpm to check that. You can then see what happens with the lights on.


i think the engine will stop, as soon as i turn the lights on...to much amps being draw from alternator...not enough for coil. just speculation.

I know it would be better to buy a 200W stator (even with low magnets in current rotor), but those are to expensive, and since i have one "old good stator" (whatever this means), i think i should first try to check everything volts and amps before tell my friend to go dip into is pockets.

Once again.
What would you do more with a digital meter, before concluding that the stator is poor and need a better one?
(already done alternator test in 6V bike...numbers seemed right)

Is this test ok? Bike must start just kicking (spark in coil)?
i could put the rectifier/regulator in circuit, but its just simpler this way for testing.


If i dont have spark with diagram above, does it mean stator is to poor?

kind regards
Carlos

Last edited by Carlos; 12/22/15 8:56 am.
Re: BSA B40 1961 6Volts to 12Volt conversion Help [Re: NickL] #631315
12/23/15 6:12 am
12/23/15 6:12 am
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Carlos Offline OP
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Thank you for your reply.

The cap is bigger then the picture. I was specific to my friend, that it needed to be RC 3A...so i believe e bought the correct one. Its 20mmx50mm. I will recheck it.

The 4A were measured with a digital meter in series with -ve of battery.
Engine not running. Turn ignition ON and constant 4A can be seen in digital meter.
So points where closed and primary coil was being "charged/shorted".
I measured the ignition coil, and its 4ohms. My digital chinese meter as 0.8ohms just by closing points..thats a big error margin. Battery voltage was around 12.5V. I agree that current should be more near 3A then 4A..maybe something wrong with ignition coil.
My next test will be connecting battery direct to ignition coil alone, and see how many amps are being draw and check if my 4ohms reading where correct.

Dont know how old are the points/condenser.
Bike was running fine with 6V.
...but i dont think that a bad capacitor would draw even more amps.
it doesn't make sense to me.

Maybe bad old wires, ignition coil or something.

What should i expect from primary and secondary coil resistance?
4 Ohms in primary? And how many Ohms in secondary?

need to recheck everything frown

Carlos



Last edited by Carlos; 12/23/15 7:12 am.
Re: BSA B40 1961 6Volts to 12Volt conversion Help [Re: Carlos] #631377
12/23/15 4:01 pm
12/23/15 4:01 pm
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quinten Offline
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Quote:
What should i expect from primary and secondary coil resistance?4 Ohms in primary? And how many Ohms in secondary?

Depends on the brand ,
Here's one example .
PVL Germany  12 volt:     
         Primary 3.8 ohms 
 Secondary 5.5k ohms (5,500 ohms)

http://www.tioc.org/boyercoildata.htm

.

Re: BSA B40 1961 6Volts to 12Volt conversion Help [Re: Carlos] #631386
12/23/15 5:21 pm
12/23/15 5:21 pm
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Andy Higham Offline
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Stop pissing about trying to test/measure at kicking speed, it is meaningless and inconsistant.
Disconnect the alternator from the rectifier.
Link GB to GY
Connect volt meter between GB/GY and WG and set to AC Volts
Start the engine and rev to about 2500-3000 RPM
If the reading is not at least 20V your alternator is no good so put it in the bin and buy a new one, they only cost about 30 pints of beer.
Use the reg/rec off a modern bike, people used to swear by the one fitted to the ho**a superdream but they are all old now. The MOSFET reg rec fitted to the Yam**a R1/R6 is the best available


1955 BSA B31 500cc "Stargazer"
1962 Greeves 200cc "Blue Meanie"
1962/67 Greeves 350
1967 Greeves 360 Challenger
1984 Suzuki GSX1100 EFE "Sorcerers Apprentice"
GM500cc sprint/LSR bike "Deofol"
Jawa 500cc "Llareggub"
2003 Aprilia RSV Mille "Lo Stregone"
Re: BSA B40 1961 6Volts to 12Volt conversion Help [Re: Carlos] #631455
12/24/15 6:04 am
12/24/15 6:04 am
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Mitch Offline
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from memory, a long time ago.... with no battery you first have to charge the cap alone in the circuit... the ignition switch has to be "open" (off) and then kick a few times to charge the cap. as soon as the switch is turned on, the cap will discharge if the points are closed, so you have to roll the engine up to start position after charging. then turn the switch on, then kick for start. when the engine turns, the points close, current stored in the cap will flow & charge the coil, then make the spark when the points open. there is no ignition switch in your diagram so the cap has no time to charge when you kick it over.... all the power is going straight to the coil through the points, thats why you read 3 volts. as a test, lift a wire off the coil & kick it over, you should see the cap charge up. also, the rectifier is shown with negative as ground but the coil has plus ground.

stuff is different now, there are several systems out there now that incorporate the battery eliminator cap. being solid state, they know when to trigger for proper ignition so plug & play (so I am told) just as if battery was there

also, somewhere did you say you had ohm reading between the stator wires & the frame? that would be bad. check the output leads by removing them from the regulator/rectifier. they should read very low from lead to lead... prolly less than an ohm. they should read infinity for either lead to ground

Last edited by Mitch; 12/24/15 6:05 am.
Re: BSA B40 1961 6Volts to 12Volt conversion Help [Re: Carlos] #631594
12/25/15 8:07 am
12/25/15 8:07 am
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Stuart Offline
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Hi Carlos,

Originally Posted By Carlos
I found the number in stator:

Originally Posted By Carlos
Rotor is the 74mm version.

According to this, in 1962, stator 47134 and rotor 423506 - making alternator 54021010 - were supplied by Lucas to BSA for the B40 Star. Unfortunately, as far as I can tell, it doesn't give the equivalent RM number for 54021010, although an educated guess says it's a RM19.

Originally Posted By Carlos
Is rotor to far out of stator?

Possibly; depends if the rotor extends about the same on the other side of the stator?

For best generation (and an early- to mid-1960's alternator needs all the help it can get), the rotor should be central in the stator both radially and axially:-

. If the rotor extends about the same beyond the stator on the other side, the rotor and stator are about central to each other axially. bigt

. If the rotor extends more or less beyond the stator on the other side, the rotor and stator are not central to each other axially. frown But that might mean the rotor is younger than the stator, and therefore more likely(?) to have better magnetism ... When Lucas superseded the RM19 and RM20 alternators with the RM21 and RM23 in the late 1960's, they also superseded the rotor with a wider one; if the rotor on this bike is further out from the stator just on one side, it could mean that a previous owner fitted a newer rotor, just without realising the stator and rotor must be axially-central with each other. But, by defintion, a 'later' wide rotor could still be nearly forty years old ...

Originally Posted By Carlos
the stator as too low output for 12V conversion?

Mmmm ... in theory, no. But, in practice, a) regulated to 12V DC, Lucas rated the RM19 for about 8.5A/100W @ 5,000 rpm (if it's an earlier RM13 or RM15, it's likely to be even less); b) the stator's about half-a-century old and has spent most of that time being vibrated in great heat; c) whatever the alternator generates depends in great part on the residual magnetism in the rotor.

Originally Posted By Carlos
Is this low voltage expected

From the alternator, yes.

Originally Posted By Carlos
...but i need 12V DC just by kicking engine?
The ignition coil it self draws 4A from the battery (thats what i measured...so i assume its the coil consumption), so its seems hard for the alternator to produce 12V 4A just by kicking!

You are confusing yourself. If it even exists, the alternator that could generate 12V AC (to be converted by the rectifier to DC) and 3A-4A at just the few rpm generated by the kickstart gearing would be bigger than the bike, so probably couldn't be turned by the kickstart.

With any alternator, AC Volts rise rapidly the faster the rotor's spun. Therefore it follows that, at kicking speed, an alternator itself is unlikely to generate anything worth talking about. As Gavin posted, why do you suppose bike makers (any vehicle makers) fit a battery with an alternator? wink

Originally Posted By Carlos
Is this test ok? Bike must start just kicking (spark in coil)?

Mmmm ...

. There is nothing there that says "Bike must start".

. Without any regulation, it isn't "12v Convertion"; the Volts at the coil are simply most of those generated by the alternator, converted to DC. It's the regulator that sets the DC Volts so, if the engine does start, the DC Volts will rise almost as rapidly as the AC Volts; as Nick has posted, if you then rev the engine, you'll almost certainly "cook the coil". frown

Originally Posted By Carlos
The 4A were measured with a digital meter in series with -ve of battery.
I measured the ignition coil, and its 4ohms.
Battery voltage was around 12.5V.
need to recheck everything

Agree. The coil cannot draw 4 Amps if it's primary resistance is 4 Ohms and the p.d. is 12.5 Volts. Ohm's Law. Also, you posted, "Draws 3A to 4A when running without lights on" in your first post to this thread.

Originally Posted By Carlos
What should i expect from primary and secondary coil resistance?

Originally Posted By quinten
Depends on the brand

Mmmm ...

Coils intended for use with points (or replacement e.i.) drawing 3A-4A when the rated Volts are applied across them is common across brands and rated Volts. So a "12 Volt" coil having a low-tension resistance of between 4 Ohms and 3 Ohms respectively is common to Lucas, Bosch, Marelli, Nippon Denso, Delco, etc., etc.; likewise is a "6 Volt" coil having a low-tension resistance of between 2 Ohms and 1.5 Ohms respectively, a "4 Volt" coil having a low-tension resistance of between 1.3 Ohms and 1 Ohm respectively, etc.

HT resistance varies a bit more between brands.

Originally Posted By Carlos
I was able to put the bike running at 12V, but because i was using a battery.
I removed the battery and inserted the capacitor instead.
There is no spark in spark-plug.


Originally Posted By Carlos
When i start to read some articles, and got some advise from you guys, you told me to convert to 12V and battery would not be needed. Just a capacitor instead of battery.

Not from me, you didn't, nor a lot of other people.

My advice: I would never, ever run a a road bike without a battery. Full stop. Period. End of.

Forty or fifty years ago, a capacitor might have had some use for those owners congentially incapable of using their biologically-supplied Mark 1 eyes and brain to inspect the maker-supplied battery-charging components for fitness-for-use. In the second decade of the 21st century, human ingenuity has produced batteries much smaller and requiring less human input to function than could have been imagined forty or fifty years ago.

Capacitors are like hand-operated oil pumps and manual advance/retard - curiosities to be amazed by while we thank God or biology for human ingenuity and advancement. What they are not is necessary or even desirable. grin

Also on this particular bike, you're dealing with half-century-old electrics that have been messed about. A capacitor is also not a silver bullet that magically fixes half-century-old messed about electrics.

The bike starts and runs on a battery. So put in a battery, if necessary a small-capacity, sealed-for-life one, but a battery. Your friend wants a capacitor? So tell him to get someone else to do it. It's a new year in a few days. Maybe next autumn or winter 2016, when your friend is ready to pay for all new electrical components and you are willing to construct a new system from the new components, you can come back to it. But, now, your friend needs to do with the bike what it is supposed to do - ride it. smile

Hope this helps and Happy Christmas. smile

Regards,

Re: BSA B40 1961 6Volts to 12Volt conversion Help [Re: Carlos] #631599
12/25/15 9:26 am
12/25/15 9:26 am
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Bolton Lancs UK
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Andy Higham Offline
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Andy Higham  Offline
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That pretty much echos my view. Fit a new alternator. a modern reg/rec and a sealed/gel/agm battery and have trouble free electrics for years


1955 BSA B31 500cc "Stargazer"
1962 Greeves 200cc "Blue Meanie"
1962/67 Greeves 350
1967 Greeves 360 Challenger
1984 Suzuki GSX1100 EFE "Sorcerers Apprentice"
GM500cc sprint/LSR bike "Deofol"
Jawa 500cc "Llareggub"
2003 Aprilia RSV Mille "Lo Stregone"
Re: BSA B40 1961 6Volts to 12Volt conversion Help [Re: Andy Higham] #637394
01/28/16 5:08 am
01/28/16 5:08 am
Joined: Aug 2012
Posts: 61
Portugal
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Carlos Offline OP
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Carlos  Offline OP
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Portugal
Hi Everyone,

I have been busy for last weeks, so i didn't have much time to get my hands dirty.

After reading all posts again, i gess i will buy a new stator for my firends bike.

Do you all agree that 3phase alternator is a better choice vs the 2 phase? Why?

Genuine Lucas 175W RM24 3-Wire Stator LU47244 would be better then Stator Genuine Lucas 47239 Single Phase 12v High Output (16A)?

Kind regards
Carlos

Re: BSA B40 1961 6Volts to 12Volt conversion Help [Re: Carlos] #637395
01/28/16 5:21 am
01/28/16 5:21 am
Joined: Dec 2004
Posts: 9,375
Scotland
kommando Online content
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kommando  Online Content
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Joined: Dec 2004
Posts: 9,375
Scotland
Quote:
Do you all agree that 3phase alternator is a better choice vs the 2 phase?


2 years ago before the intro of good H4 LED's I would have recommended the 3 phase over the single phase. Its use allows the use of main lights at all times and the battery stays charged.


Quote:
Why?


Not for the slightly higher max output but because at lower engine speeds the output is far higher than a single phase.

So on an 850 Commando in 4th in a 30mph limit area your output with a 3 phase will be much higher than a single phase. At 50 mph on a B40 the difference will be much less.

However with the advent of LED's with their lower wattage for the same or greater light output a single phase will cope so I am no longer upgrading from single to 3 phase but using LED's.

Re: BSA B40 1961 6Volts to 12Volt conversion Help [Re: kommando] #637437
01/28/16 2:42 pm
01/28/16 2:42 pm
Joined: Jun 2002
Posts: 9,962
Scotland
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Stuart Offline
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Stuart  Offline
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Hi Carlos,

Originally Posted By Carlos
Genuine Lucas 175W RM24 3-Wire Stator LU47244
Genuine Lucas 47239 Single Phase 12v High Output (16A)?

Unfortunately, This Is Not True:-

. In 1979 (?), the "Lucas" that made the original parts for most of our motorcycles was taken over by a US company called TRW.

. For many years, TRW showed little interest in the the market for Lucas parts for old motorcycles (and cars, vans, etc.). Brands like Sparx, Wassell, etc. were allowed under some sort of arrangement to produce pattern copies of 'original Lucas' parts but not to use the "Lucas" logo. TRW did not police the quality of these parts and most pattern parts makers gained a reputation for, at best, very variable quality. frown

. However, until two or three years (?) ago, amongst the "etc." was a small manufacturing unit in GB making or having made high-quality reproductions of some 'original Lucas' parts for anyone that would pay them - usually one of the large British-based Britbike parts wholesalers. These parts were originally branded "Lucas" but, more recently, "LAP" (Lucas Aftermarket Parts?)

. Unfortunately, last year, TRW granted Wassell a licence to use the "Lucas" logo and packaging for replica Lucas parts for old vehicles. cry As any search of this and TriumphRat's Classic, Vintage and Veteran forums will show, Wassell have lost no time in filling "Lucas"-branded boxes with their poor-quality rubbish, while using the "Genuine" word, which they are nothing of the sort. mad

. "Original Lucas" never, ever made a "16 Amp" single-phase (two-wire) alternator. From the late 1960's to 1978, Lucas made the RM21 and RM23 single-phase, two-wire alternators; Lucas rated the RM21 for 10.5A and 120W @ 5,000 rpm and the RM23 for 14.5A and 180W @ 5,000 rpm. In 1978, Lucas superseded the RM21 and RM23 with two versions of the RM24 3-wire, 3-phase alternator; these two 3-phase stators were rated exactly the same as the RM21 and RM23. And, by "superseded", I mean that, in 1978, Lucas stopped making the RM21 and RM23 and only made the two versions of the RM24.

. The problem with the "16A" claim is it's never accompanied by a rpm figure; I happen to know that a RM23 will produce 16A, if the rotor is spinning at about 8,000 rpm ... All the posts I've read by old Britbike owners who have bought and fitted a "16A" (or "20A") alternator also say that they have never seen these Amps actually produced at the rpm their bikes can manage. frown

Originally Posted By Carlos
3phase alternator is a better choice vs the 2 phase? Why?

Originally Posted By kommando
Not for the slightly higher max output but because at lower engine speeds the output is far higher than a single phase.

This is not borne out by the original Lucas figures:-

. Both the 'high-output' single-phase (RM23) and 3-phase (RM24) were rated exactly the same - 14.5A/180W @ 5,000 rpm.

. The difference at lower rpm was, @ 2,400 rpm, the single-phase produced 75% of rated while the 3-phase produced 85% of rated - 10.875A and 12.325A respectively.

Originally Posted By Carlos
i will buy a new stator for my firends bike.

Apart from the rubbish being peddled about "Genuine Lucas", it is reasonable to assume that, whether you/he buy/s a new complete alternator (I recommend a new rotor as well, unless you can be sure the existing rotor is no more than a few years old), whoever made it and whether it is single-phase or 3-phase, it will produce more power than the alternator on the bike at present:-

. A 3-phase alternator must be connected to a 3-phase regulator/rectifier but a single-phase alternator can be connected to a single-phase or 3-phase regulator/rectifier (uses only two of the three connections).

. Are you sure the extra power will not introduce more problems to the old wiring and switches?

Hope this helps.

Regards,

Re: BSA B40 1961 6Volts to 12Volt conversion Help [Re: Carlos] #638013
02/01/16 1:19 pm
02/01/16 1:19 pm
Joined: Aug 2012
Posts: 61
Portugal
C
Carlos Offline OP
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Carlos  Offline OP
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Portugal
Hi Everyone,

Once again, thank you for all the information shared.
Thank you Thank you Thank you.
I am learning fast as much as i am getting confused smile

I was at my friend house, but didn't get my hands dirty..just measure the coil again, and its definitely 3.2ohms. in the past i forgot to discount the meter error. (Chinese 0.8ohms :))

Changing rotor is definitely out of his league for the next months. Low on money.

To be able to make the bike work in 12V, reliable, i think my best option is to get the highest Amp stator possible. 14.5A or 16A. Even with low magnet field (but i think rotor is ok and seems to be changed in the past) i think it will survive for rural rides with lights on.

Quote:
Are you sure the extra power will not introduce more problems to the old wiring and switches?

Since 12V uses half the amps, it should be ok. Extra power makes me safe for any possible low magnetic field.

Quote:
The problem with the "16A" claim is it's never accompanied by a rpm figure; I happen to know that a RM23 will produce 16A, if the rotor is spinning at about 8,000 rpm ... All the posts I've read by old Britbike owners who have bought and fitted a "16A" (or "20A") alternator also say that they have never seen these Amps actually produced at the rpm their bikes can manage. frown


I agree..
But if they never saw 16A with those 16A stators, then with the 10A stator it should be even worse @ same RPM.
But without graphics to compare, its just speculation.

Is fedek dot com the cheapest offer in the online market?

Kind regards
Carlos

Re: BSA B40 1961 6Volts to 12Volt conversion Help [Re: Carlos] #638037
02/01/16 3:15 pm
02/01/16 3:15 pm
Joined: Jun 2002
Posts: 9,962
Scotland
S
Stuart Offline
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Stuart  Offline
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Joined: Jun 2002
Posts: 9,962
Scotland
Hi Carlos,

Originally Posted By Carlos
Originally Posted By Stuart
The problem with the "16A" claim is it's never accompanied by a rpm figure; I happen to know that a RM23 will produce 16A, if the rotor is spinning at about 8,000 rpm ... All the posts I've read by old Britbike owners who have bought and fitted a "16A" (or "20A") alternator also say that they have never seen these Amps actually produced at the rpm their bikes can manage.

But if they never saw 16A with those 16A stators, then with the 10A stator it should be even worse @ same RPM.

No.

The difference is that 'original Lucas' did produce "10A" (well, 10.5A) stators - the RM21 single-phase from the late 1960's to 1978 and RM24 'low-output' 3-phase from 1978 onwards. And they produce(d) the 10.5A @ 5,000 rpm, so a pattern one is easy to check, and return to the vendor if faulty. bigt

By the way, I found two 'pre-Wassell' Lucas RM24 'low-output' 3-phase stator suppliers in GB - http://www.chris-knight-mcs.co.uk/acatal...Tiger-1699.html and http://www.ebay.co.uk/itm/GENUINE-LUCAS-...&rmvSB=true. If you enter "Lucas 47252" (the original Lucas part number) into your internet search engine, all other vendors uses the same (Wassell-supplied?) picture which, if you enlarge it, shows the Wassell "WW" part number on the box! clap Note how different the pre-Wassell and Wassell stators look ...

By the way 2, the eBay one is only "150W" when the regulation allows the DC to rise to ~14.3V (when everything else is using more "W" wink ); at the ~12V 'original Lucas' used, it's the "120W" 'original Lucas' quoted ...

Hope this helps.

Regards,

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