I had thought about the steady cadence thing too. It might add some of the lost efficiency back. and yeah there needs to
be a gear up to spin the alternator faster than pedaling cadence, that allows you to customize it for the rider.
It may be for my design that all I really care about is the rider can actually limp home if the battery is dead. I can't
quite decide. Since you are completely stuck if the motor dies, maybe even that isn't important. But I was also thinking
that 60W of solar coupled with the pedaling might be adequate to substitute for more efficient direct drive pedaling....
The lightest, most efficient, cheapest generators I have found after a brief search are the PM alternators for wind
generators. But the alternator OEM wont just tell me what the efficiency is though ( "they're good" "well then how do
you size props?" "We research...research" meaning we do trial and error... So how do they know it's relatively
efficient? Why because they sell them, thats why.....
thanks
John
Jeffrey Blamey wrote:
A comment on the operation: Most cyclists try to keep to a certain
cadence, at least the touring folks I used to be one of. I can see this
as a great way to keep your rpms fairly constant, even be pedaling when
stopped at a light or stop sign. So from that standpoint it is a good
thing. There are losses in the generation of power in the form of heat
both in the generator and in the battery, the wires will lose something
(less so if you make sure your wire gage is sufficient). The controlling
issue may be finding a generator matched to your battery bank, probably
not an issue if you are using 12 or 24 volts but is above that voltage.
Real Goods sells a human power generator which can recharge 12 or 24
volt batteries but it is very pricey @ $599, part number is 17330. There
is no picture on their site that I can find.
On 10/24/07, *john fisher* <[EMAIL PROTECTED]
<mailto:[EMAIL PROTECTED]>> wrote:
I am thinking through a high-powered 3 wheel elec-bicycle. For
packaging reasons, using the human-powered drive
component through direct drive is awkward. So what I am wondering is
how much efficiency would I give up by pedalling a
generator/alternator and charging the battery.
assuming:
the human produces about 150W steady
a few pounds of extra weight is acceptable.
the direct-drive efficiency is basically 100%
any opinions? is it a 50% loss? even greater?
John
