Another question or two on the little blue can

Is it safe to say that the little blue can (capistor) is functioning correctly (in other words not faulty and creating a drain on the battery) if the ohm meter shows the same resistance with either the capastor hooked up or all of the brown/blue wires connected together.

Operating with a battery, does the little blue can (capistor) improve starting of the bike if the battery is slightly low?

Q1 Sounds logical but not an electrician so could be wrong

Q2 No because it only comes into oeration if you disconnect the battery

This little blue can , Is it under the seat forward of the battery with a spring type wire holder and if i have electronic ignition (pazon) does it still work as it was intended. When i fitted the pazon i removed the 2 capacitors that sit on the coils as per the directions i seem to remember so maybe the blue can capacitor is now redundant anyway.

I never managed to start my Commando using the 2MC capacitor when it had a Boyer ignition even though I could get weak sparks at the plugs with the plugs out if I kicked it over hard enough.
I tried the the same thing after fitting a Tri-Spark Classic Twin ignition and I couldn't generate any sparks at all, so I've disconnected the 2MC.

L.A.B. said:

I never managed to start my Commando using the 2MC capacitor when it had a Boyer ignition even though I could get weak sparks at the plugs with the plugs out if I kicked it over hard enough.
I tried the the same thing after fitting a Tri-Spark Classic Twin ignition and I couldn't generate any sparks at all, so I've disconnected the 2MC.

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If it was the original capacitor, there is almost no chance that it would start a bike. As mentioned here before the lifespan of a 2MC isn't that long. Try a modern replacement capacitor and it'll probably work.

Another urban legend repeated til the Internet makes it true. There are a lot of variables that affect the life of an electrolytic capacitor. It is much longer than the 18 months figure being spouted here though. Mine is fine and it is the original from Jan. 1972. The electrolyte can dry up inside, yes, but they can be tested using an ESR meter. This is an AC ohmmeter. I think the Lucas manual has another more practical test where it is charged up and then left for a certain time and remeasured.

swooshdave said:

If it was the original capacitor, there is almost no chance that it would start a bike. As mentioned here before the lifespan of a 2MC isn't that long. Try a modern replacement capacitor and it'll probably work.

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Tri-Spark ignitions should work down to lower voltages than a Boyer, so there may be some other reason why the digital Tri-Spark system wouldn't work off the 2MC?

batrider said:

I think the Lucas manual has another more practical test where it is charged up and then left for a certain time and remeasured.

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The 2MC test is done by disconnecting the capacitor from the electrical system, and then connected directly to a 12V battery (observing correct polarity) for 5 seconds, and volt tested after 5 minutes. The voltmeter reading should be not less than 9V if the 2MC is OK.

My 2MC also appears to be rather ancient (unusually for Lucas electrical components, there's no apparent date of manufacture on it?) but the test shows 11V after 5 mins.
And it has always taken more than 24 hours to fully discharge itself when it is connected to the electrical system but disconnected from the battery.

batrider said:

Another urban legend repeated til the Internet makes it true.

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I did say "almost no chance". That leaves room for exceptions.

Everything on the Internet is true. I heard that on Wikipedia...

So it seems like the little blue can (capasitor) is only there to be used in the event that a person is off somewhere and the battery will not start the bike. On the other hand, no matter how long the capasitor actually lasts, when it does give up it is likely to drain the battery to the point that it won't start the bike and then there won't be the emergency capasitor available to start the bike.

Looks to me like a good thing to remove expecially since most times we are riding for pleasure and know the condition of the battery not to mention the improved battery situation with the gel cells.

Yellow_Cad said:

So it seems like the little blue can (capasitor) is only there to be used in the event that a person is off somewhere and the battery will not start the bike. On the other hand, no matter how long the capasitor actually lasts, when it does give up it is likely to drain the battery to the point that it won't start the bike and then there won't be the emergency capasitor available to start the bike.

Looks to me like a good thing to remove expecially since most times we are riding for pleasure and know the condition of the battery not to mention the improved battery situation with the gel cells.

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You could just leave it where it is, and disconnect its ground wire? That way it can't drain the battery, but it could always be reconnected again in an emergency?

For info on the the failure modes of electrolytic capacitors:

http://www.chemi-con.com/u7002/table2.pdf for those who like techno explorations. (United Chemi-con is a big manufacturer of aluminum electrolytic can capacitors.)

Yes they do fail eventually but we are riding Nortons and enjoy tempting fate. Mine ain't broke so I will leave it in its oil mist coated splendor. :twisted:

LAB - If I get a chance I will test my 2MC over the weekend using the voltage decay method. Your capacitor seems to be a good one. I have a homebrew ESR meter too. I like this stuff.... Now I'm curious.

My 71 has the original capacitor. I blew the main fuse once but happened to be up a good hill. A rolling start was successful with the boyer. I suppose the capacitor was of some help or maybe just enough o/p from the alternator. Surprised me. Ran home fine on alt. power.

batrider said:

Another urban legend repeated til the Internet makes it true. There are a lot of variables that affect the life of an electrolytic capacitor. It is much longer than the 18 months figure being spouted here though.

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Really? Another urban myth, eh? Well, if so, it predates the internet. The following is a quote from my 1971 Triumph workshop manual (page H19 if you want to look it up, but of course, why would you when you've got your own hubristic sense of certainty to fall back on!):

Storage Life of Model 2MC Capacitor

The life of the 2MC is very much affected by storage in high temperatures. The higher the temperature the shorter its shelf life. At normal termperatures, i.e. 20C (68F) it will have a shelf life of about 18 months. At 40C (86F) about 9 to 12 months. Therefore, storing in a cool place will maintain their efficiency.

So, if the 18 month figure is being "spouted" it was spouted by Triumph a long time ago. If you've ot one that has lasted 30-odd years good luck to you. I suppose it proves that old Joe Lucas' company did something right despite all the maligning they've endure over the years.

The decay test is detailed in both my Nroton and my Triumph workshop manuals. So, batrider, as it was news to you it would appear that, despite your love of techno explorations, you haven't actually read the book. You know what they say: When all else fails, read the instructions.

And, yeah, your opinionate posts with your contemptuous tone do piss me off.

FWIW I spent 7 of my 30 year Electrical Engineering career designing electronic power supplies and the company I worked for had a 5 year warrantee on its products. We used Sprague and Mallory aluminum electrolytics and they held up fine over that time frame.

maylar said:

FWIW I spent 7 of my 30 year Electrical Engineering career designing electronic power supplies and the company I worked for had a 5 year warrantee on its products. We used Sprague and Mallory aluminum electrolytics and they held up fine over that time frame.

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Was that powered up and in use? What about sitting on a shelf? I have some old cans in my junk box, but I think I would buy new ones for a critical project. One of my video casette players broke and the fix was to replace a whole bunch of electrolytics even though it was on most of the time.

Jean

Jeandr said:

Was that powered up and in use? What about sitting on a shelf? I have some old cans in my junk box, but I think I would buy new ones for a critical project. One of my video casette players broke and the fix was to replace a whole bunch of electrolytics even though it was on most of the time.

Jean

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If you think about it, virtually all electronic equipment has electrolytics. What's the expected life span of a radio, TV, or computer? Certainly not months. I have capacitors in my parts bin that are over 10 years old and I would use them in a project without question.

The environment they are exposed to.. electrical, mechanical and thermal.. also has an effect on the service life. Perhaps our infamous Blue Cans were not well chosen for the application. Mine was removed a couple years ago when I measured it to be non-functional (slight leakage, near zero capacitance). So I guess 30+ years in a nasty vibrating Norton is too much to ask.