Subject:
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Re: Heavily modified 8880 chassis, succesfully motorised and solar powered.
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Newsgroups:
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lugnet.technic
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Date:
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Fri, 14 Feb 2003 18:51:18 GMT
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Viewed:
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1945 times
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> Hi Gillis,
> I have been following this thread with great interest since you first
> posted. My recommendation? Buy two of the new style Lego motors. They are
> very, very, very efficient. They will be much cheaper than an industrial
> quality motor, and much lighter as well. I think you will be surprised at
> the efficiency of the new motors in comparison to the old ones. The new
> motors also have internal gearing, so you will be able to simplify the
> geartrain on your car which will improve efficiency even further. Heck, I'm
> so certain this will work I would lend you a couple of my motors if I lived
> closer.
>
> > I'd also need
> > another diff to properly share the load between the motors.
>
> This isn't necessary. The load will be shared regardless. Its like a tandem
> bicycle. You could actually try just one of the new style motors and the
> performance should improve dramatically.
>
> Rob
It's just that according to this page:
http://www.philohome.com/motors/motorcomp.htm the new style lego motors'
efficiency is only 54% at 9v (or even 47% for the 'newer' (?) style V9
motor)...which is not even close to 90%...Of course that test may be a
little off, but would that account for a difference of 36%? I'd doubt it...
I'd have to connect the 2 motors in serial(also can't be done with pure lego
parts) otherwise their combined resistance is too low, which results in
little power from the solar panel; very high current, but VERY low voltage,
but in seriel their combined resistance will most likely be quite high,
which causes the other extreme; high voltage, but very low current. Ideally
you'd strike a balance where the things connected to the solar panel have a
resistance of about 25 Ohms, on a sunny day that will cause about 16volts at
some .55-.60Amps from the solar panel. Connecting two motors without a diff
is do-able, but in serial, one of the motors will probably get more voltage
than the other, which makes the 'tandem connection' less optimal.
You're totally right about the weight though. The motor I'm looking to buy
weighs in at some 160grams, much more than 2 lego motors.
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