Another one of those Motor questions

[Michael GilliganParticipant @michaelgilligan61133]

Today’s impossible question …

How much does the quality of these Start & Run capacitors vary between brands ?

The ebay item to which Les kindly pointed is near the bottom of the price range, and for double that I have found a MECO version.

https://www.ebay.co.uk/itm/224373277605

 

Although Motorcyclists have often joked about the terrible quality of Italian electrics, MECO seems to tell a good story:

https://mecocapacitors.com/en/company/

https://mecocapacitors.com/en/products/motor-start-and-run/cmi4-series/

 

… and I’ve found this useful note elsewhere:

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Any ‘value for money ‘ exercise would  obviously need to include shipping costs, and the estimated cost of failure [!] but I am drawn towards the MECO brand.

 

MichaelG.

[Robert Atkinson 2Participant @robertatkinson2]

Duncan,

That test only works with an incandescent lightbulb. They are hard to come by these days.
Some multimeters will measure capacitance of a capacitor but not many will measure other critical parameters for a motor start capacitor like ESR and leakage.

The capacitor linked is ideal

[Ian PParticipant @ianp]

The Meco capacitor spec gives a design life of 10,000 hours which is presumably continuously running, so a long time in terms of a shredder in a domestic situation. Stop start usage probably reduces the life expectancy though.

As it happens, last weekend I was in conversation with a now retired director of ‘Chassis and Powertrain’ engineering at a luxury car manufacturer and learned a couple of interesting facts, one is the incredibly short life (in terms of running hours) of the gearbox when in ‘reverse’. Have a guess for this weeks quiz!

Second, is that when they introduced engine ‘Stop-Start’ feature as part of their fuel economy measures, no mechanical changes/upgrades whatsoever were needed or made to the existing starter motor, ring gear etc were all found to be capable of lasting the original design life of the car.

Ian P

 

[Robert Atkinson 2Participant @robertatkinson2]

<10 hours

[duncan webster 1Participant @duncanwebster1]

<1 hour

They should sell special models for use in Cornwall with all those narrow sunken lanes

[Ian PParticipant @ianp]

Duncan is nearest, 2 hours was the figure I was told.

 

 

[Nick WheelerParticipant @nickwheeler]

Ian, you should ask your friend what the car manufacturers consider the design life to be. The usual figure suggested(but not admitted to) is depressingly low.

[Ian PParticipant @ianp]

To be honest it was me who interpreted what he said into car ‘design life’. His point was that he and his engineers were surprised themselves by the durability of the starter system components that were now going to be called upon many more times than the original design engineers had anticipated.

Ian P

 

 

[Nick WheelerParticipant @nickwheeler]

Sorry, I meant design life for the whole car not just parts

[Ian PParticipant @ianp]

Nick, I understood your question but I’m not sure he would have a figure for the design life of his car brand. I suspect as with most modern vehicles the mechanicals will long outlast the date the car manufacturers support the software.

Ian P

[John Doe 2Participant @johndoe2]

Just for the record; I for one wasn’t criticising the paper shredder electronics as such, just wondering why they needed to be so complicated for a mere paper shredder.

It has a reed relay to detect presence of the paper bin, so that might use a transistor. It has a run-on timer, so that is one 555 timer chip, (or a capacitor), and another transistor. (Or an AND logic gate for both functions instead of the transistors).

It needs a power supply to run the low voltage electronics = a diode bridge rectifier and another few transistors or a power supply IC.

Then perhaps a motor load detector, looking at current draw = another transistor or two.

Perhaps it uses PWM for the motor, and soft start, and possibly some really clever electronics to detect a full paper bin ?

Definitely a ‘Rolls Royce’ of paper shredders.

(But even with all “those electronics”, seemingly no electronic way of limiting time of continuous motor use or motor temperature, except for a mechanical bi-metallic switch in the motor windings.)

Are you sure it doesn’t have a hidden document scanner that records each page as it enters the shredder, and a Wi-Fi transmitter ? That would be a good way to snoop on people who were destroying sensitive documents !

 

 

 

[NealebParticipant @nealeb]

My first shredder came as a surplus item after an office clear-out. Once it had broken (as mentioned – shattered gear rather than motor or electronics) and I started looking at specs of potential replacements I was surprised by the very short quoted duty cycle of typical “home” shredders. Often something like 3 mins in 30 mins – that’s really not a lot. I presume that this is down to a heavily-loaded (or under-specified?) motor and something like that really could indeed do with some kind of temperature monitoring or overload cutout of some kind. Especially seeing how easily these smaller shredders can be stalled.

[Michael GilliganParticipant @michaelgilligan61133]

Whilst not “Industrial” my shredder is certainly not the typical domestic toy … the specs [linked earlier] confirm that, and the rating of the motor speaks for itself, and nothing mechanical has broken [yet]

380W would drive an ML7 size lathe very adequately.

MichaelG.

[Michael GilliganParticipant @michaelgilligan61133]

There’s life in that old shredder !

New Capacitor and a quick re-assembly … she’s going well

Thanks for all the good advice

MichaelG

[Les Jones 1Participant @lesjones1]

Good news Michael. I always like to now the conclusion to a problem. May times on some electrical / electronic forums the original poster just disappears.
I have only just realised that the posts went into a second page. I would not have been able to give any advice on motor start/run capacitor manufacturers as it is probably over 50 years since I needed to replace one. My domestic shredder only has a tiny series wound motor so the the motor in Michael’s shredder is MUCH more substantial.

Les.

[Andy_GParticipant @andy_g]

Well done!

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