Building an electric... bike!? (electric motors)

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I'd like to build an electric bike/trike (or something) with our kids.
I was considering a Briggs & Stratton "Etek Motor" - until I realised
it has brushes.

Would I be correct in thinking a brushless (dc) motor is more
suitable?  Is that what those nasty k-mart scooters use??

Does a brushless dc motor have "consumables" (for want of a better
word) like brushes that I'm not aware of, that will need to be
replaced?  

I guess basically I'm after suggestions for a long-lasting, reliable
motor with a good bit of torque.  Something that won't burn out in 12
months time and we can pull out and build something else with.

Also while I think of it, I'm so cheap I don't even want to pay
$1.40/L just to get bread and milk anymore.  ; )  So if anyone knows
of any Australian sites where someone has built electric
bikes/trikes/cars themselves - that would be appreciated.   Or good US
one...  There is lots of US sites of course, but parts they refer to
are often not available here - but open to suggestions from either
side of the pond.

Thanks for reading...

Allan

Re: Building an electric... bike!? (electric motors)


mmm Lot of time and energy to design/build or rather reinvent
old technology with all the associated costs - which would
probably be far less overall than using the car <shrug>, so
start the spreadhseet now...

Petrol is cheaper now than it was 10 years ago, all else
considered, and milk is even cheaper, so take some of what you
gain on milk and put it to the petrol and think of doing
something useful with your time...

<chuckle>

ie. Petrol = Money,
    Time is the killer

cheers

Mike



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Regards
Mike
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Re: Building an electric... bike!? (electric motors)



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Er...  Thanks for the reply, but a 7 and a 10 year old can't drive a
full sized car around our backyard.  ; )

Anyone else here done/know of anything along these lines?

Allan

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Re: Building an electric... bike!? (electric motors)


snipped-for-privacy@COLDhotmail.com says...
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The more direct route is a small petrol engine, such as off a radio
control two stroke petrol car, car more interesting to make work
and far more long term interest retained by participants. If you go
the route of electric motor and associated batteries, interest will
diminish as the performance will lack and the batteries will invariably
fail and the project will fizzle out...

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See it done a couple of times, electric bike = nice idea in principle
until you do some time management. As its for kids there are many
more opportunities to learn with mechanics and overall design concepts
if you go down the ICE route...



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Regards
Mike
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Re: Building an electric... bike!? (electric motors)



snipped-for-privacy@COLDhotmail.com says...
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Yep - we have a small two stroke lying around.  Still have that in the
back of my mind as a last resort.  Thanks!

Re: Building an electric... bike!? (electric motors)


I have plans for a steam powered push bike.
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Re: Building an electric... bike!? (electric motors)


snipped-for-privacy@optusnet.com.au says...
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<chuckle>

The gearing on a penny farthing would be of interest but,
where do you put the reservoir for the torque convertor,

<shrug>


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Mike
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Re: Building an electric... bike!? (electric motors)


On Tue, 6 Jun 2006 15:39:27 +1000, "Max Harding vk3jin"

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You have my respect.  I would love to own the Pritchard Steam car.
Wish I had the knowledge to build a steam... anything.

Re: Building an electric... bike!? (electric motors)


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Its actually much easier than you'd think:-

a.  Boil water in a vessel that can keep a high pressure
b.  Use the steam to push a piston with a valve that switches
    the flow off when its on the return, ie Pipes and valve.
c.  Condense the steam back to water and pump this back into
    boiler.

These days you dont need proprietary mechanical valves, use cheap
electronics and solenoid valves, you can then vary the timing to
suit etc.

Have seen a V8 chevy motor many years ago that was configured to
run off a waste steam source, what the guy did was:-

1.  Change the valve timing, this is also easier than you'd think.
2.  Use an oil/water separator on the sump, so the sump wouldnt
    slowly fill up with water, I think it was some centrifugal
    system to ensure any emulsion was nicely cleared.

No need for sparks or ignition etc, (I seem to recall also he ran
some pressure sensors off the old plug holes) just need the inlet
manifold to be able to hold the full waste steam pressure. In his
situation he didnt worry about recycling the steam to a condensor,
just let it exhaust to atmosphere - this was fairly efficient because
the exhaust would be straight to air so lower exit pressure and no need
for a water pump back to the bolier. If I recall corectly it ran
at about 2000 to 2400 rpms or so. Based on BMEP he could have got
something like 250 Hp from his waste steam source, might even be
legacy links on web, last time I looked was 12 years ago <shrug>



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Mike
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Re: Building an electric... bike!? (electric motors)


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I wonder if it ran a week, or a month, before rusting out?

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says...
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Dont know, I wondered about that at the time, though if its 'dry'
steam and the engine is in continuous use, without much opportunity
for condensation and presumably the oil/water separator is working
or there isnt much steam blowby then you'd expect some considerable
time, wonder how long ordinary older steam engines ran with their
cast iron pistons ?


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Mike
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says...
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I saw an article years ago about a VW bug - still have it somewhere, I
might dig it out.  I *think* it said titanium pistons were fitted.
Anyway, point being of course engines are modified to prevent rust.  I
have always wished I could learn to build steam engines - maybe one
day I can find a decent book on it.  [sigh]

Re: Building an electric... bike!? (electric motors)


snipped-for-privacy@COLDhotmail.com says...

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Yes I would like to see that, I have a heat engine project on the back
burner at moment <great pun>. Basically arranging best use of pressure,
also have a pair of unused VL/Nissan 6 cyl engines in the back shed
that havent rusted yet, have in mind using them at some point though I
robbed one of them of big end bearings for my VLT...

Steam engines are really really simple, just pressure and applied to
a piston, thats effectively it...

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Mike
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Yep, but how to build the thing so it doesn't explode...  You'd need
engineering qualifications surely - and then how to please the RTA is
the next problem.

That "Pritchard Steam Car" guy - his father invented a type of
valve...  I think it was because steam engines have poor acceleration?
His valve overcame whatever the problem was anyway.  Some collector in
WA bought the only car the father and son made and hid it away.  What
a waste!

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Trouble is, the Rankin cycle doesn't give you anywhere near the same
energy output as the Otto cycle.

Someone worked on this and came up with a modified steam engine that
improved on teh Rankin cycle, using supercritical pressure (3200psi) and
temperatures of about 1200 deg F. Nasty thing to have in an accident
though ...

See here for some more info:
http://www.greencarcongress.com/concept_engines/index.html

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snipped-for-privacy@COLDhotmail.com says...
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Most materials suppliers of things like pipes and valves will point
you to tables or specs, just need a bit of math skills and if in doubt
ask them, and/or go to traditional boiler suppliers/manufacturers, you can
get a heap of skills from a TAFE course for boiler making too, it is really
easy to find out the basic data - the trick is to focus on it for a few
minutes so it makes sense. Do this in concert with BMEP for an engine
and one soon finds out just what pressure and flow you need to make any
particular piston engine perform well enough from a steam source.

You dont need qualifications to build one for your workshop or to research
but you sure do if you sell, install etc for anyone else..

Road Traffic Authority would surely be an issue so for that, get a classic
car from 60 years ago as a starting point ;)

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Poor efficiency, average locomotive was about 7%, reminds me of the
largest ones built in USA, 6000 hp at around the late 1930's, that means
they threw away a *huge* amount of heat to develop 6000hp to pull
cariages, yep they did have overweight people even in the 1930's

<chuckle>

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Mike
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Re: Building an electric... bike!? (electric motors)



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I've looked where the article should be and couldn't find it.  I did
find this one though (each link is one page):

http://www.yousendit.com/transfer.php?action=download&ufid5E%3260B5221955D7
http://www.yousendit.com/transfer.php?action=download&ufid06%88DC843F20B179
http://www.yousendit.com/transfer.php?action=download&ufid9F%255ED55E205F34

It prints better than it looks on a computer screen too.  Not much in
the way of practical info though.

Allan

Re: Building an electric... bike!? (electric motors)


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How do you work that one out? In 10 years petrol has more than doubled in
price, my income has gone up far less than double in the same period.


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Re: Building an electric... bike!? (electric motors)


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Inflation, value of money roughly halves each 10 years, however, if oil
had kept pace with inflation since the mid 70's it woould be around $140
per barrel and petrol would be arounf $2.50/L.

If it was possible to work the real value petrol is about 10% cheaper
in real terms over last 30 years, prob only 5% cheaper from last 10 but
there are going to be all sorts of debatable factors in that equation.

Although people in UK are paying around $2 per litre already, we have it
quite good despite fact most of income goes to government coffers to pay
for problematic capital works like tunnels or a nuclear power plant <sigh>

There are going to be many anomalies in any change in value, nothing
keeps pace the same as any economic average, your income level has its
own issues, some might be situational, who knows.


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Mike
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Re: Building an electric... bike!? (electric motors)



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I thought that estimate was every 23 years?  Anyway...

We use about 51 Litres per week.  This costs us about $58.14 when it
was about $1.14.  Now it's $1.40 (or is it even more today?), which
means we now pay $71.40 - $13.26 more.  Our income hasn't increased
and add to that the extra expense from other things being dragged up
because of extra freight costs...

Personally, I  hope they keep right on going.  The faster and higher
the better.  They've taken it too far and the cutting of their own
throats has begun.  The more expensive fuel is, the more people will
say I won't pay this anymore and just dump petrol altogether.

Going by our figures (which are lower than most folks), that's a
yearly petrol cost of $3713, a 2-year cost of $7426 and a 3-year cost
of $11,138.  (And that's assuming it doesn't rise any further, which
it will.)  So assuming it will go up further, for the price of about
the next 2.5 years worth of fuel, I could convert a car to electric
today.

Now all I've got to do, is discover how you get something like that
passed for rego and I'll get started.  ; )

Allan

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