"Welcome to the real world, she said to me, condescendingly..."

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"Welcome to the real world, she said to me, condescendingly..."

cowtown
<<< oooh sour grapes from the dubester : ) be prepared to be bitch slapped
for your insolence : )

quick googling indicates that typical human biking power is around
80watt going 12mph. efficiency aside that would be about an hour with a
dewalt pack right? let's say we get only half, how long is that... : )
this ebike: http://www.wheelzofcelebration.com/products.html with a
360Wh pack (little over 4 dewalt packs) claims towards 25 mile range.
how much is a quarter of that? is it 1 mile? : )

he shoots, he scores : )

Dan >>>

No, air ball...

Bill's numbers for 15mph work out to a very liberal 40 miles per kwh,  
without acceleration, hills, or wind: 3 miles from a singe Dewalt pack  
is actually pretty impressive. Don't quote claimed range from a  
website if you haven't actually done it yourself - most of EV distance  
specs are pure fiction and being off by a full 50% is not unusual.

E-bikes may list a "400 watt motor", but that's the *labeled rating*  
-- the controller pumps in much more than that to maintain 20mph  
(which is the Federal limit for production e-bikes).

As for the human equivalent:

"Figures from Bicycling Science 2nd ed., Whitt and Wilson, MIT Press  
1994, p186:

Note that figures for human-powered transportation are in incremental  
consumption above the resting level.

Road bicycle plus rider:

4mph 8.4 kcal/km
10mph 15.6 kcal/km
15mph 24.4 kcal/km"

Feel free to do the math, but 15mph works out to ~45 wt-hrs/mi. Maybe  
it was done with a fat guy on a fat-tired bike...

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Re: "Welcome to the real world, she said to me, condescendingly..."

Dan Frederiksen-2
Aren't those values for human energy consumption rather than crank power?
as measured by oxygen intake through a mouthpiece..

Dan

[hidden email] wrote:

> Dan >>>
>
> No, air ball...
>
> Bill's numbers for 15mph work out to a very liberal 40 miles per kwh,  
> without acceleration, hills, or wind: 3 miles from a singe Dewalt pack  
> is actually pretty impressive. Don't quote claimed range from a  
> website if you haven't actually done it yourself - most of EV distance  
> specs are pure fiction and being off by a full 50% is not unusual.
>
> E-bikes may list a "400 watt motor", but that's the *labeled rating*  
> -- the controller pumps in much more than that to maintain 20mph  
> (which is the Federal limit for production e-bikes).
>
> As for the human equivalent:
>
> "Figures from Bicycling Science 2nd ed., Whitt and Wilson, MIT Press  
> 1994, p186:
>
> Note that figures for human-powered transportation are in incremental  
> consumption above the resting level.
>
> Road bicycle plus rider:
>
> 4mph 8.4 kcal/km
> 10mph 15.6 kcal/km
> 15mph 24.4 kcal/km"
>
> Feel free to do the math, but 15mph works out to ~45 wt-hrs/mi. Maybe  
> it was done with a fat guy on a fat-tired bike...
>
> _______________________________________________
> For subscription options, see
> http://lists.sjsu.edu/mailman/listinfo/ev
>
>  

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Re: "Welcome to the real world, she said to me, condescendingly..."

Evan Tuer
In reply to this post by cowtown
On 8/14/07, [hidden email] <[hidden email]> wrote:

> Feel free to do the math, but 15mph works out to ~45 wt-hrs/mi. Maybe
> it was done with a fat guy on a fat-tired bike...
>

I recently got my E-bike (non hub motor) going with a 10AH, ~24V pack
of prismatic LiFePo4 cells.  I have a 20 mile each way commute
(charging at work) and it takes a little over an hour each way,
depending on the wind.  This is with plenty of manual input from me,
and there are some serious hills.
It's an old, heavy mountain bike but I have road tyres at high pressure.

So far I have not hit the under-voltage limit of the battery - I don't
have an accurate measurement of the energy used yet but I plan to fit
an E-meter temporarily to find out.
A Kill-a-watt type meter on the charger indicates 0.27kWh used so it's
probably about empty after each trip.

The battery came with a neat little BMS incidentally, with 8
dissipative regulators and a large FET to disconnect the load at
undervoltage or overcurrent / over temperature.  I put LEDs on the
regulator and it does a blinkenlights effect in the approved manner -
3.9V per cell at end of charge.

Anyway it compares well with my other EV which uses about 30 times the
energy for the same trip, although it takes half the time :)

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