Dyson

Dave Plowman (News) presented the following explanation :

Which all sums up into far less cleaning power and capability from a cordless model, when compared to a mains model.
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On 04/04/2018 17:16, Harry Bloomfield wrote:

.... here we go ....
its a bit like light bulbs really - which is brighter - a 60W incandescant or a 20W recent LED? The new generation of *digital* (not my word) high revving brushless motors are far more efficient than the old mains powered contraptions that power corded machines. That, coupled with a free flowing cyclonic filter system produces far more usable suction watts at the cleaning head - where it matters. We really DON'T need 1000W motors to power vacuum cleaners anymore.
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On Wed, 04 Apr 2018 17:32:46 +0100, Andy Bennet wrote:

You're way out of date with that LED GLS lamp example. These days it's a comparison between a 125LPW 6.5W 810Lm LED lamp and an American 806Lm 120v 750 hour incandescent lamp. Compared to a UK 240v 1000 hour incandescent, the same LED lamp is noticeably brighter.

Not that great an improvement when a 1930s Hoover universal motor would be some 90 to 95 percent efficient and look not too dissimilar to a 1980s vacuum cleaner universal motor with a similar efficiency rating.
A modern DC brushless (so called 'digital') motor gains its efficiency rating of 95 to 99 percent (depending on how hard you're trying to squeeze the design for a maximum horsepower rating for a given volume/ mass) by virtue of neodymium magnets and a maximum working RPM rating.

That's true of the recent breed of vacuum cleaners that were being marketed on their power consumption alone as their headline figure for suction power. However, you still need several hundred watts worth of suction power in a reasonably efficacious vacuum cleaner. Bagless cyclonic filtering is the major factor in improved efficacy but it can't magically improve its suckiness to the point where a mere 120W motor can outperform a more conventional 700W vacuum cleaner.
Unlike the LED GLS lamp versus the incandescent GLS lamp case where a 100W tungsten filament lamp converted only some 2 to 3 percent of its input energy into useful light versus a modern day LED converting 25 to 30 percent into light, the vacuum cleaner motor is only improving its efficiency from a low of 85% to a high of 95 to 98 percent at best.
Quite frankly, aside from specific requirements for cordless operation, I'd rather they saved the weight and expense of the battery pack by powering a high power, high efficiency neodymium magnet brushless high speed DC motor from a lightweight mains powered smpsu built into the handheld vacuum cleaner so that I can enjoy the cleaning power of a five to seven hundred watt lightweight vacuum cleaner without the worry of a battery going flat before I'd finished vacuuming. The drag from a lightweight mains flex is far less of a strain compared to that of lugging the weight of a rechargeable battery around with the vacuum cleaner itself.
--
Johnny B Good

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Andy Bennet was thinking very hard :

Well, not really, or even a close comparison.

Only if you beleive the Dyson hype.

Even the older vacs were using cyclonic filter and yes, it does make them more efficient/ require less power.

Unfortunately, that is not entirely true. A 50W+ motor is still not able to do the same work as a conventional tech 1000W motor, no matter how much you read the Dyson hype. Motors were already pretty efficient and efficiency is all that could be improved. Assuming the 1000W motor were only 50% efficient, making the same motor 100% efficient only reduces the consumption to 500W. You are trying to suggest that the 50W is ten times more efficient than 100%, which defies the laws of physics. One HP is still and will remain 746 watts.
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On Wed, 04 Apr 2018 21:35:03 +0100, Harry Bloomfield wrote:

Very nicely put! :-)
--
Johnny B Good

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On 04/04/18 21:35, Harry Bloomfield wrote:

1/. Dyson motors are not 'digital': They are in fact offspring of the motors used in model aircraft. They use electronic commutation, thats all. And decent magnets.
2/. They are only a litle more efficient. A worts catse cheap as shot can motor that ypu might fidn in a toothebrisus is about 50% edfdiecint at noirmla working. A well made breusless rinning at a devent poi8nt on te curce mightcrack 90%.
3/. They are however a lot lighter due to the use of neodymium permanent magnets.You camn easily get a brake horspower out if something the sized of a coffee mug or smaller.
4/. However batteries to generate a brake horsepower are much bigger and heavier and will only stay charged about 5 minutes at full chat.
5/. Ergo Dyson is a lying shit. And peole who lie about priducets dint do it because the produceys ell themselves without lyoing.
6/. Ergo Dyson products are shit too.
,
--
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foolish, and by the rulers as useful.
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Well lets hope they do better here then;)....
https://goo.gl/maps/F8emgY6aPSk

--
Tony Sayer


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You talk about efficient use of electricity when you have to re-charge a battery? C'mon. If his DC motors are so much better than his mains ones he could use them in the mains machines too with a built in power supply.
--
*America is so advanced that even the chairs are electric.

Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
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On 05/04/2018 00:17, Dave Plowman (News) wrote:

Factually correct. However, the portable Dyson hangs on the wall in the kitchen. While I'm brewing the tea or cooking the sausages or whatever it is no effort to unhook the vac and have a quick whizz round. Unlikely to happen with a corded machine - haul it out of the cupboard, unwind the flex, plug it in, fix the right attachment, vacuum, remove attachment, unplug it, recoil the flex and put it back in the cupboard. As far as I am concerned it's all a matter of convenience and the Dyson portable just does that fine. I'm a happy bunny. Period.
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You have your dyson hung on the wall for all to see, but a mains cleaner has to be kept out of sight in a cupboard somewhere?
And when using your Dyson, you carry all the attachments round with you?
It probably also comes down to how many convenient mains sockets you have for cleaning. When I re-wired this house I made sure there were plenty. Even adding one if I discovered a 'blind spot' when hoovering.
I also don't have anywhere I'd want a Dyson hung on a wall. It would have to be rigged up in the same cupboard as the mains one. But I already have a small cordless one conveniently situated for small spills etc.
--
*HOW IS IT POSSIBLE TO HAVE A CIVIL WAR?

Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
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On 2018-04-04, Harry Bloomfield wrote:

That's generally true for power tools of any kind: cordless = more convenient; mains = more power, no battery life problems.
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So what is the running time on one charge? Although it wouldn't need to be as long as for an upright.
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*The average person falls asleep in seven minutes *

Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
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