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I've Found Somewhere My Scooter Can't Go


hilldweller
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Been for a little run this morning on my scooter now that the weather is a bit more temperate.

Went to have a look at some of the beautiful old and not so old houses around Ranmoor and Carsick. I came back up Snaithing Lane and spotted the little snicket that runs up the side of the Claremont Hospital and recognised it as somewhere I'd walked up donkey's years ago. It looked just a bit wider than my mobility scooter and the gradient at the bottom didn't look too steep.

I'll give it a go I thought, the bottom bit wasn't a problem but then it got steeper and steeper. I couldn't turn around and reversing was out of the question. I carried on and decided that any minute the thing was going to flip over backwards. I was hanging over the front tiller when very suddenly it stopped with a jerk and I nearly went over the front. The circuit breaker (50 amps at 24 volts) had tripped and the electro-magnetic brake come on.

I let it cool down a bit, re-set the breaker and made my way slowly to the road at the top.

Looking on the computer the average gradient is about 1 in 4.5 but parts of it must be about 1 in 3.

I'll leave the little snickets alone in future unless I can see all the way along.

HD

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Been for a little run this morning on my scooter now that the weather is a bit more temperate.

Went to have a look at some of the beautiful old and not so old houses around Ranmoor and Carsick. I came back up Snaithing Lane and spotted the little snicket that runs up the side of the Claremont Hospital and recognised it as somewhere I'd walked up donkey's years ago. It looked just a bit wider than my mobility scooter and the gradient at the bottom didn't look too steep.

I'll give it a go I thought, the bottom bit wasn't a problem but then it got steeper and steeper. I couldn't turn around and reversing was out of the question. I carried on and decided that any minute the thing was going to flip over backwards. I was hanging over the front tiller when very suddenly it stopped with a jerk and I nearly went over the front. The circuit breaker (50 amps at 24 volts) had tripped and the electro-magnetic brake come on.

I let it cool down a bit, re-set the breaker and made my way slowly to the road at the top.

Looking on the computer the average gradient is about 1 in 4.5 but parts of it must be about 1 in 3.

I'll leave the little snickets alone in future unless I can see all the way along.

HD

OK so lets take a physics technical look at your scooter.

The stall or cut out point is at 50 Amps. (Must have some pretty thick wiring to handle that current without getting overheated)

That represents a maximum power consumption of 50 x 24 = 1200 Watts, or just under 2 horsepower.

depending on the efficiency of the scooter the power output would be somewhat less, - probably still well over 1 horsepower.

Now, if we knew the all up mass of the scooter + load (you + any extra cargo) in kg I should be able to calculate an approximate maximum speed.

..and if we knew the battery charge in Amp-Hours we could calculate an approximate run time (very approximate as under load the batteries would not be able to maintain a 50 Amp output) and from both the speed and time we can then calculate a maximum range under full load.

But something tells me you probably already know the answers to all of these questions, - both calculated and experimentally observed by trying it out.

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OK so lets take a physics technical look at your scooter.

The stall or cut out point is at 50 Amps. (Must have some pretty thick wiring to handle that current without getting overheated)

That represents a maximum power consumption of 50 x 24 = 1200 Watts, or just under 2 horsepower.

depending on the efficiency of the scooter the power output would be somewhat less, - probably still well over 1 horsepower.

Now, if we knew the all up mass of the scooter + load (you + any extra cargo) in kg I should be able to calculate an approximate maximum speed.

..and if we knew the battery charge in Amp-Hours we could calculate an approximate run time (very approximate as under load the batteries would not be able to maintain a 50 Amp output) and from both the speed and time we can then calculate a maximum range under full load.

But something tells me you probably already know the answers to all of these questions, - both calculated and experimentally observed by trying it out.

In 1985 when the infamous SINCLAIR C5 came out, some good physics stuidents of mine asked questions like this about it before coming to the conclusion that it was not worth buying one. After this, for a short time while the topic was in vogue, I then had several mathematical physics "homework exercises" based on the SINCLAIR C5

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OK so lets take a physics technical look at your scooter.

The stall or cut out point is at 50 Amps. (Must have some pretty thick wiring to handle that current without getting overheated)

That represents a maximum power consumption of 50 x 24 = 1200 Watts, or just under 2 horsepower.

depending on the efficiency of the scooter the power output would be somewhat less, - probably still well over 1 horsepower.

Now, if we knew the all up mass of the scooter + load (you + any extra cargo) in kg I should be able to calculate an approximate maximum speed.

..and if we knew the battery charge in Amp-Hours we could calculate an approximate run time (very approximate as under load the batteries would not be able to maintain a 50 Amp output) and from both the speed and time we can then calculate a maximum range under full load.

But something tells me you probably already know the answers to all of these questions, - both calculated and experimentally observed by trying it out.

A few further figures to help your calculations. lol

The quoted nominal horsepower of the motor is 2 hp. The 2 batteries when new were rated at 80 A/h each. The wiring is doubled wired (paralled) in something around 10 square millimeters. The large industrial type circuit breaker has a type 3 inverse current/time characteristic which according to my well-thumbed copy of the IEE regs will take around 90 amps to trip in the 3 minutes I estimate we were climbing. Allowing for a little heating of the breaker in the travel before this, it would be a bit less than that value. When we got to the top of the hill I put my hand on the motor and it was just nicely aired. It was made by the Pihsiang Machinery Manufacturing Company Limited of Taiwan as was the entire thing.!

The thing weighs about 3 cwt (150 kg) and I weigh about 100 kg.

The speed is limited by design to 8 mph (12 km/h), but it does slow down under heavy load. and the maximum safe working slope is 8 degrees (whoops). Max range is quoted at 35 miles (carrying Twiggy I should think).

If your calculations prove that the thing cannot move off the spot, remember that according to the most carefully worked calculations, bumble bees cannot fly.

I must admit that this is the first time the breaker has tripped and normally it takes me up Roper Hill without protest.

HD

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If your calculations prove that the thing cannot move off the spot, remember that according to the most carefully worked calculations, bumble bees cannot fly.

I must admit that this is the first time the breaker has tripped and normally it takes me up Roper Hill without protest.

HD

I'll vouch for that, impressive bit of hill climbing!

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In 1985 when the infamous SINCLAIR C5 came out, some good physics stuidents of mine asked questions like this about it before coming to the conclusion that it was not worth buying one. After this, for a short time while the topic was in vogue, I then had several mathematical physics "homework exercises" based on the SINCLAIR C5

When I worked in the Engineering Department at Sheffield Hallam, one of our students obtained a surplus C5 motor for a project. It was identical in size and outward appearance to a Italian made Hoover washing machine motor that some-one else brought in. Obviously it was designed for a much lower operating voltage. From memory it was a permanent magnet field motor. When I worked in electrical traction, small vehicle motors for milk floats and the like were usually equipped with a series connected wound field.

HD

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A few further figures to help your calculations. lol

The quoted nominal horsepower of the motor is 2 hp. The 2 batteries when new were rated at 80 A/h each. The wiring is doubled wired (paralled) in something around 10 square millimeters. The large industrial type circuit breaker has a type 3 inverse current/time characteristic which according to my well-thumbed copy of the IEE regs will take around 90 amps to trip in the 3 minutes I estimate we were climbing. Allowing for a little heating of the breaker in the travel before this, it would be a bit less than that value. When we got to the top of the hill I put my hand on the motor and it was just nicely aired. It was made by the Pihsiang Machinery Manufacturing Company Limited of Taiwan as was the entire thing.!

The thing weighs about 3 cwt (150 kg) and I weigh about 100 kg.

The speed is limited by design to 8 mph (12 km/h), but it does slow down under heavy load. and the maximum safe working slope is 8 degrees (whoops). Max range is quoted at 35 miles (carrying Twiggy I should think).

HD

Looks like the specification tells us quite a bit.

Drawing 50 amps would give a maximum load running time to flat battery of about an hour and a half and a range, based on its speed of no more than 12 miles.

But that is the worst case scenario as it is highly unlikely to be under that sort of load for any length of time.

Would the range of 35 miles be about right on a flat road with no wind?

(Even further down a steep hill!! lol )

If the range was 35 miles, then at top speed it would take around 4 hours 25 minutes, and the load on the battery would be around 9 Amps.

However, if the specifications make claims that are difficult to believe the best way to find out is to try it out experimentally.

After all, my car claims it will do around 56mpg on the urban cycle, but I consistently get less than this and I don't do boy racer Clarkson style driving, I actually go out to achieve fuel economy.

But I still can't get better than about 51mpg.

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If your calculations prove that the thing cannot move off the spot, remember that according to the most carefully worked calculations, bumble bees cannot fly.

HD

I thought that scientists COULD now show how bees were able to fly, - and lets face it, they do it very well.

The problem is that all aircraft have fixed wings with aerofoil shaped lifting sections, but birds and insects have flexible wings which can be flapped (frequently very rapidly) and flexed to provide control, while still maintaining an aerofoil lifting surface with the correct angle of attack.

In short these animals must be much smarter and quicker thinking than we give them credit for in order to be able to do this.

Aircraft designs are relatively simple when compared to "Ornithopter" designs which are intended to fly like birds by flapping the wings.

I am sure that scientists these days would be more interested in protecting and saving bees from impending extinction, a serious current problem, especially as bees are vital to pollenation, rather than wondering how they fly.

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If the range was 35 miles, then at top speed it would take around 4 hours 25 minutes, and the load on the battery would be around 9 Amps.

However, if the specifications make claims that are difficult to believe the best way to find out is to try it out experimentally.

I'm all in favour of experimentation but in this case there is a tiny snag.

If I set out with fully charged batteries then when they eventually give out, I should be in a bit of a pickle with no more battery power, and even if I had taken my battery charger with me the absence of mains power might be a bit of a snag. Also even if power were available I should have to wait at least 12 hours for the batteries to be fully charged. My recovery service doesn't cover flat batteries.

Of course I could drive around the block about several hundred times but that might be regarded as somewhat bizarre by the local Lodgemorons.

HD

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I'm all in favour of experimentation but in this case there is a tiny snag.

If I set out with fully charged batteries then when they eventually give out, I should be in a bit of a pickle with no more battery power, and even if I had taken my battery charger with me the absence of mains power might be a bit of a snag. Also even if power were available I should have to wait at least 12 hours for the batteries to be fully charged. My recovery service doesn't cover flat batteries.

Of course I could drive around the block about several hundred times but that might be regarded as somewhat bizarre by the local Lodgemorons.

HD

We could build a "rolling road" contraption in your garage or back garden so that you could experiment without actually going anywhere! ;-)

This would be even better as you could fit an ergometer / dynamometer to the rolling road and measure the scooters power output directly.

You would also be able, using a braking force, to simulate different loads and hill gradients.

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When I worked in the Engineering Department at Sheffield Hallam, one of our students obtained a surplus C5 motor for a project. It was identical in size and outward appearance to a Italian made Hoover washing machine motor that some-one else brought in. Obviously it was designed for a much lower operating voltage. From memory it was a permanent magnet field motor. When I worked in electrical traction, small vehicle motors for milk floats and the like were usually equipped with a series connected wound field.

HD

I seem to remember that at the time of the C5 it was claimed that it was powered by a hoover washing machine motor, but, outward appearances being almost identical, this clearly cannot be the case.

As you point out, there is a big difference in voltage, 240V for the washing machine and either 12V or 24V for the C5

More importantly though, the washing machine is running on AC (mains) and the C5 on DC (batteries).

This would require some very important differences inside the motor, such as the use of sliprings for the brushes in the AC motor, but some sort of commutator in the DC equivalent motor to serve the same purpose.

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OK so lets take a physics technical look at your scooter.

The stall or cut out point is at 50 Amps. (Must have some pretty thick wiring to handle that current without getting overheated)

That represents a maximum power consumption of 50 x 24 = 1200 Watts, or just under 2 horsepower.

depending on the efficiency of the scooter the power output would be somewhat less, - probably still well over 1 horsepower.

Now, if we knew the all up mass of the scooter + load (you + any extra cargo) in kg I should be able to calculate an approximate maximum speed.

..and if we knew the battery charge in Amp-Hours we could calculate an approximate run time (very approximate as under load the batteries would not be able to maintain a 50 Amp output) and from both the speed and time we can then calculate a maximum range under full load.

But something tells me you probably already know the answers to all of these questions, - both calculated and experimentally observed by trying it out.

Take a look at this hilldweller, -

It is a January 2008 GCSE Physics exam question, and it is almost identical in it's nature and scope to the problems we seem to be contemplating here.

In the year this exam was taken I had a top set Physics group and I had taught them all this sort of stuff so to them this question should have been 10 easy marks.

Unfortunately, some kids compartmentalise their knowledge and cannot (or don't want to) think across subject boundaries.

"I can't do this one Sir, - it's a maths qustion" or "This isn't physics, it's maths"

Once they overcome the science / maths barrier and start using the two together then suddenly questions like this are just a piece of cake.

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I seem to remember that at the time of the C5 it was claimed that it was powered by a hoover washing machine motor, but, outward appearances being almost identical, this clearly cannot be the case.

As you point out, there is a big difference in voltage, 240V for the washing machine and either 12V or 24V for the C5

More importantly though, the washing machine is running on AC (mains) and the C5 on DC (batteries).

This would require some very important differences inside the motor, such as the use of sliprings for the brushes in the AC motor, but some sort of commutator in the DC equivalent motor to serve the same purpose.

I think that most washing machines have been fitted with D.C. commutator/brush motors for a number of years now. I suppose this is for speed control/reversing purposes. The drive electronics providing the necessary rectification.

The washing machine motor I remember was certainly a brush motor but obviously wound for a higher operating voltage derived from the mains without transformation. The brushes in low voltage motors have a high percentage of copper content to minimise volt drop.

HD

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I think that most washing machines have been fitted with D.C. commutator/brush motors for a number of years now. I suppose this is for speed control/reversing purposes. The drive electronics providing the necessary rectification.

The washing machine motor I remember was certainly a brush motor but obviously wound for a higher operating voltage derived from the mains without transformation. The brushes in low voltage motors have a high percentage of copper content to minimise volt drop.

HD

That seems to make sense, a DC motor can be controlled just by changing the potential across it / current through it and can easily be reversed by changing the polarity. Both of these things would be more difficult to achieve with AC.

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Going back to the title of this topic,

I thought I had found somewhere else that hilldwellers scooter couldn't go

However, it seems that NASA managed to do it 40 years ago

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I could handle the Science, never the Maths.

Lower Sixth Biology, Geology, Chemisty, Physics, General Studies (last one compulsory)

Upper Sixth Biology, Geology, Chemistry ... couldn't hack the Maths.

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I could handle the Science, never the Maths.

Lower Sixth Biology, Geology, Chemisty, Physics, General Studies (last one compulsory)

Upper Sixth Biology, Geology, Chemistry ... couldn't hack the Maths.

having said that, I couldn't hack History at all and look at my interest now.

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Going back to the title of this topic,

I thought I had found somewhere else that hilldwellers scooter couldn't go

However, it seems that NASA managed to do it 40 years ago

My Shoprider Cordoba is a rather dashing shiny black with twin head-lights and go-faster stripes, but nearly there. The ride would be a bit harsh though, with the equivalent of nearly another 15 lbs/square inch in the tyres.

If I had a cellar like Wallace and Gromit I could build a space-ship and go and look for myself.

HD

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If I had a cellar like Wallace and Gromit I could build a space-ship and go and look for myself.

HD

Would that be before or after you had finished making the ergometer rolling road contraption to test your scooter out on. lol

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I could handle the Science, never the Maths.

Lower Sixth Biology, Geology, Chemisty, Physics, General Studies (last one compulsory)

Upper Sixth Biology, Geology, Chemistry ... couldn't hack the Maths.

As a teacher I believe that maths should be INTEGRATED into science and not DIFFERENTIATED from it.

(Are you any good at CALCULUS Richard?)

By the simple ADDITION of the 2 subjects the students understanding of it is MULTIPLIED EXPONENTIALLY

(Have you noticed that no one seems to understand LOGARITHMS any more :unsure: )

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Would that be before or after you had finished making the ergometer rolling road contraption to test your scooter out on. lol

I'm giving the dynometer idea a rain check for now (or I would if I knew what one was).

The batteries are now 3 years old and like me no longer in the first flush of youth.

I'm working on the principle that the LED battery-charge indicator is approximately correct and I never let it drop below approx 60% before I turn around and head for home.

Up to now I have always managed to get back with at least a couple of segments still lit.

If I ever run out of puff completely I have a cunning plan because the recovery scheme doesn't cover a flat battery. If it ever happens then I shall know if my cunning plan worked.

Cue Blackadder theme music.

HD

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(Have you noticed that no one seems to understand LOGARITHMS any more :unsure: )

A quick lesson in LOGARITHMS for our younger members (those under 50 who have had always had the luxury of a personal electronic calculator}

Lesson by

Professor DaveH of the University of Arbourthorne (a close rival to Oxford and Cambridge)

Professor Stuart0742 of the University of Hackenthorpe (origin of the famous work the Hackenthorpe Book Of Lies)

LOGARITHMS

When Noah's Ark finally came to rest at the Mansfield Road / Hollinsend Road crossroads after 40 days in the flood Noah released all the animals he had saved, a male and female of each species, and he said unto them "Go forth and MULTIPLY, and repopulate this barren land". (Well, - it was Mansfield Road!)

Now on the ark Noah had a pair of snakes, and these snakes were ADDERS

The ADDERS had a problem, they couldn't MULTIPLY as Noah had told them to, they could only ADD.

This unfortunate situation persisted until the 17th century when a mathematician called Napier devised LOGARITHMS

LOGARITHMS allowed the ADDERS to MULTIPLY just by ADDING

They also allowed the SUBTRACTERS to DIVIDE.

Those that could already MULTIPLY could now be RAISED TO POWERS

Those that could already DIVIDE could now be ROOTED

So one way or another everyone was happy, all thanks to LOGARITHMS

In the nineteenth century along came another mathematician called Euler who was on to a good NUMBER,

He came up with NATURAL LOGARITHMS which then allowed RECIPROCAL FUNCTIONS to be INTEGRATED.

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I'm giving the dynometer idea a rain check for now (or I would if I knew what one was).

The batteries are now 3 years old and like me no longer in the first flush of youth.

I'm working on the principle that the LED battery-charge indicator is approximately correct and I never let it drop below approx 60% before I turn around and head for home.

Up to now I have always managed to get back with at least a couple of segments still lit.

If I ever run out of puff completely I have a cunning plan because the recovery scheme doesn't cover a flat battery. If it ever happens then I shall know if my cunning plan worked.

Cue Blackadder theme music.

HD

Now, if you are out on it and are a bit late coming home (say from a boozer) and it has turned dark that means you would have to use those "twin headlights" you mentioned. They must be a fair drain on the batteries.

Does having the headlights on shorten the range significantly?

Does the scooter slow down if you put the headlight on?

Do the light go dim if you have to climb a steep hill and put extra load on the motor causing it to draw more current?

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I could handle the Science, never the Maths.

Lower Sixth Biology, Geology, Chemisty, Physics, General Studies (last one compulsory)

Upper Sixth Biology, Geology, Chemistry ... couldn't hack the Maths.

Richard,

Can you do the 2008 GCSE Physics question about hilldwellers scooter that I posted in post #12?

You need to do this for homework, I expect it on my desk by 9 o'clock on Monday morning.

If you fail to attempt or hand this work in on time you will get 3 strokes of the cane on each hand.

If you score less than half marks you will get a one hour after school detention to do some extra science and maths revision work.

Do I make myself clear Boy!!!

(Took me years of training and experience to come up with a post like that! lol )

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Now, if you are out on it and are a bit late coming home (say from a boozer) and it has turned dark that means you would have to use those "twin headlights" you mentioned. They must be a fair drain on the batteries.

Does having the headlights on shorten the range significantly?

Does the scooter slow down if you put the headlight on?

Do the light go dim if you have to climb a steep hill and put extra load on the motor causing it to draw more current?

The "headlights" are fitted with 5 watt side-lamp bulbs and I would never think of going out in the dark on my steed. I shouldn't think the couple of amps extra load would make much difference to battery voltage and hence scooter speed. I think the lighting is there to comply with the letter of the law and not a lot more.

I use the indicators a lot more and they are quite bright, the only snag is the very annoying high pitched beep-beep sounder.

I'm afraid that pub trips after dark are off the menu nowadays, with the price of draught pub beer going in to the stratosphere I'd rather relax in my own home with a bottle of decent real ale. Never been a big drinker, well I am a big drinker but I don't drink much.

HD

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