Re: Extending the range of an electric bike...

Tim Williams wrote:
"ehsjr" <ehsjr@xxxxxxxxxxxxxxxx> wrote in message
news:WrWRh.344$eC.326@xxxxxxxxxxx

You must know some things no one else knows. :-)


Nope, it all factors out. It's just a comparison.

Nope. Unsupported assumptions.
1) That all of the energy was extracted from the battery
2) That the rate of discharge when running the bike is the
same as the rate of discharge at which the battery was rated.
3) That the range was limited to 12 miles.
4) That the battery was fully charged and in brand new condition.

_Serious_ flaws for a design group.


Do you honestly know of any bicyclist who can put out 0.8HP for 42 minutes?

I made no statements about the hp developed by a cyclist. But let
me throw some "phoney math", based on facts, at you.
The Gossamer Albatross requires .3 hp to fly in still air. It
was driven across the channel (22.2) miles in 2 hours and 49 minutes.
To determine how much hp the cyclist could have generated for
42 minutes: 189/42*.3 = 1.35
: end phoney math :

The typical human can do about 1/4HP as I recall, making that figure a good
basis for the power consumed at 17MPH. Depending on bearing quality/tire
pressure, wind resistance, "uphill both ways", etc., of course.

We have no idea what speed 1/4 hp will produce.
On a mountain bike in high gear on a level road,
you go like a bat out of hell with very little
hp input, as compared to climbing a steep hill in
low gear where you are barely moving but providing
maximum hp input.

And we are cluless about the course conditions for his bike,
as you allude to.





In other words, we have no idea of the work done
nor the energy expended.


Presumably, the energy expended was 432Wh, since the OP implied that 12
miles is the maximum range on the given batteries.

Assumption, see above. The op stated "it does 12 miles at 17 mph
quite comfortably with no input from the rider."


It's all just math and makes sense when looked at.

Only if you allow the assumptions. It's a huge leap
from the "there is this much hp in a battery" math
to the "therefore we used that much hp". As pointed
out, we have no clue how much power was initially
available nor how much was used.

And even if you accept some assumptions, the conclusion
that "there are huge losses somewhere in the system" could
just as easily be "your battery is very weak" or some such.

Ed

Of course, facts don't
produce such comments as:

What's this "we" paleface.

which reflects badly on his attitude...

Tim

--
"Librarians are hiding something." - Steven Colbert
Website @ http://webpages.charter.net/dawill/tmoranwms


.

Relevant Pages

  • Re: Kicking a few ideas around in my head (SF), would like to get feedback
    ... (Energy as currency vs. entropy) ... Energizer stay in business if every battery they sell is at a loss? ... be a necessary reduced efficiency? ... electrons get stored on the clouds. ...
    (rec.arts.sf.science)
  • Re: Lithium-Battery Cars May Deliver 300 Miles Per Charge
    ... If one's desire is to go 300 miles and hold a speed of, ... It takes a certain amount of energy to do that. ... in a battery, and draining the battery into an electric motor...... ... If, however, you only want to go 30 miles at 30 mph, you get ...
    (soc.retirement)
  • Re: Extending the range of an electric bike...
    ... That all of the energy was extracted from the battery ... He did not say 12 miles is the range. ... it does 12 miles at 17 mph quite comfortably ...
    (sci.electronics.design)
  • Re: How many hydrogen cars on the road in the US today?
    ... energy than this) 4.5 miles per KWh is typical experience of EV ... Because its energy density is 0.035 kWh/kg versus YOUR technology ... battery away every 3 years. ... I said 48 miles range on 15kWh. ...
    (sci.energy.hydrogen)
  • Re: Solar, not nuclear
    ... Improved lifestyles can be had at a third of their energy consumption, ... release new models with a differently constructed battery pack such that the ... manufacturer x an exhorbitant amount of money to use manufacturer Ys ... This is true...although there is no need to replace ALL fossil plants, ...
    (sci.energy)