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My MSuper V3s+ Ascent of Mount Wilson


Marty Backe

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I try to think of it this way.  A rider moving at 20 kph on a perfectly level road uses up X amount of power.  If that road is tilted progressively down, the power needed becomes less and less until it reaches zero power at a certain angle as gravity takes over providing the power needed to keep the rider moving at 20 kph while overcoming resistance forces.  Even though the motor is turning the net power needed to move at 20 kph is zero.

If the tilt increases further the power available exceeds what is needed to move at 20 kph so the speed increases.  If the rider were to brake to maintain 20 kph and not go over that, there is extra resistance so the power available is redirected into the battery pack.  The resistance is due to the power needed to charge the battery pack up from a lower voltage to a higher one so it is the electric current in the reverse direction that is helping to brake.  Or that's my theory.  I'm no physicsologist or electronicsologist so don't quote me on that.  :whistling:

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1 hour ago, meepmeepmayer said:

Pretty sure, if the motor turns but you need no or little power, that generated power has to be stored. So just rolling down a hill without braking should be optimal for regeneration. And braking costs you because deceleration needs power. Only reason for braking should be so you don't get faster on your own infinitely, but "doing nothing" (no braking) while roling down a hill should give you back the most.

Just a guess.

No, conceptually this is (IMHO) all wrong. 

First point if you are neither consuming nor generating any power and you are going down a hill you are going to accelerate until such point that wind resistance gives you a terminal velocity.  Remember ‘G’ is 9.81 Metres per second per second - the ACCELERATION due to gravity. I would have thought terminal velocity on a reasonably steep hill would be at least 80MPH, probably over 100MPH.

  • So just going down a hill at constant speed requires that your wheel IS braking and, in doing so, generating charge - I would agree this is probably the most effective charge generation technique.

Secondly, there has been various discussions about consuming power whilst braking and graphs that seem to prove it. I’m sorry but I just do not see it - it just does not fit the physical laws we know - particularly conservation of energy: http://www.bbc.co.uk/schools/gcsebitesize/science/add_ocr_pre_2011/explaining_motion/energychangesrev5.shtml

  1. For a start why do fully charged wheels have a problem with braking down hill. If braking consumed energy or was capable of consuming energy,  there would absolutely no problem.
  2. Secondly you have a mass with significant kinetic energy speeding down a hill, and you consume energy to brake that wheel (say to a standstill) where has all that energy gone? It cannot simply disappear. Conventional brakes convert that energy to friction heat - an awful lot of heat. You haven’t got any conventional brakes so the only “things” you have got that can convert energy are the battery by converting it back to potential energy or the MOSFET’s. If it did get converted to heat in the MOSFET’s they would get a damn sight hotter going down hill than up, which is nonsense.

Think about it: going up a hill, heat is merely a byproduct of poor efficiency, the vast majority of the energy is being converted to the potential energy of being higher up. Going down hill and actually consuming energy whilst braking would mean that entire reduction in your kinetic energy would have to be going through your MOSFET’s as heat - that is ridiculous.

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57 minutes ago, Keith said:

You haven’t got any conventional brakes so the only “things” you have got that can convert energy are the battery by converting it back to potential energy or the MOSFET’s. If it did get converted to heat in the MOSFET’s they would get a damn sight hotter going down hill than up, which is nonsense.

Just a small detail - most of the energy would be for heating the motor coils, mosfets less. But still too much for continous breaking.

Great summary and explanation!

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  • 3 weeks later...

Marty, I always enjoy your videos.  Thanks for taking the time to produce them. I wish I had the patience to do that.  I also wish I had some mountains around here in Florida, but the best I have is miniature "hills" in the Jensen Beach area that have a "height" of about 50 feet at most.  Maybe I'll have to come to California and try Mount Wilson some day.

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