proposed circuit for bicycle battery recharger

[Ken Smith]

That works, but if you add current limiting then you will need two
circuits in place of one.

I assume you are limiting the charging current.

How about: A PTC device in series with the dynamo would interrupt the
current if it gets too high and reconnect the circuit the next time the
rider slowed down.

Switching off the charging when the batteries are full up sounds like a
bigger problem. Maybe the diodes could be SCRs.

 

[Ken Smith]

4700uF
||+
.------------|---o--||----o-->|--o-----o-------------.
| | | || | | | |
| - | | | | |+
| ^ | | | | ---
.-. | '-->|--. | | |+ -
( ~ ) GND|-o | | | --- --- 4 cell
dynamo '-' | | | | --- 4700uF - NiMH
2.5-5V | V .-->|--|-' | | --- (4.8V)
RMS | - | | | | -
| | | | | | ---
| | | ||+ | | | -
'------------|---o--||--o---->|--' | |
|| | |
4700uF | |
=== ===
GND GND

How about:


Many uF D2
----!!--+--->!------>
! !
- ---
( ) ^ D1 To Battery
_ !
! !
--------+----------->


It has a lot less parts.
If you wish to control the charging, opening the connection of one of the
diodes with some sort of switching device would seem the easiest way to
go.

Most bicycle generators have one side grounded and most lighting also take
their ground via the frame. This makes life a bit harder because the
obvious use of an N-MOSFET can't be done.

 

[mike]

That works, but if you add current limiting then you will need two
circuits in place of one.



In half wave, those stacked caps act as resistors of value 1/(8*F*C)
IIRC in so far as determining the average output DC voltage.

Still don't know what you're getting at. All I care about is that
electrons go into the battery. Don't care when or how. Don't care about
voltage or current. The battery sets the relationship.
Many electrons good; few electrons bad.
I want the most possible electron flow until the cutoff condition is
reached.

Think you're hung up on the classical definition of a voltage doubler
driving a classical load. That's irrelevant when you're clever enough
to stick the batteries into the middle of (what used to be a classical)
doubler.

I'd try a tilt sensor. Charge battery only when going down hill;-)

What do they use for lighting generators these days?
The one I have rubs the side of the wheel. It's a VERY noticeable drag.
mike


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[mike]

Hey dumbass,

How would *any* lighting system "improve the effort needed to peddle the
bike?" I own generator/light systems that have shunt regulators
built-in, with no modification. What do you know about the generators
built for bikes? You think some 1/2 or 1 watt zener means squat in
terms of the power needed to pedal a bike? Even a slacker can put out a
100 watts with little problem. LANCE can put out over 400 watts for > 1
hr straight. The shunt is cost effective protection, not perfection,
and not important in terms of total efficiency.

And what is with the stupid top-posting?

Cool, where do I get one of those 400W bike generators?
mike




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[John Popelish]

Cool, where do I get one of those 400W bike generators?

Under the hood of a junked car.

 

[Tom (at tomsweb.net)]

Mike,

As I stated in my first post on the subject, you don't need to double
the voltage. You need to put the load where the voltage exists. All
you need do is split the battery into two pairs
of cells and put them where the series caps are. Delete the third cap too.

Unfortunately that's not very convenient as my battery case has only
the + and - connections of the 4-pack coming out on a DC plug, and I
would rather use the standard connector to keep things tidy and
splashproof instead of soldering additional wires into the thing etc.

By the way, several people assume the load is a light, it is not, it is
a GPS. This is isolated from the chassis which makes things easier.

Charge termination will be done by a micro with ADC that monitors the
battery voltage (and puts it on a display if I press a button), so I
can let the micro switch off a FET when the battery has spent a certain
time at a sufficiently high average voltage. If I find a use for it, I
could perhaps even monitor the frequency of the ripple on the battery
voltage, which is proportional to cycling speed and thus available
energy.

greetings,
Tom

 

[mike]

Mike,




Unfortunately that's not very convenient as my battery case has only
the + and - connections of the 4-pack coming out on a DC plug, and I
would rather use the standard connector to keep things tidy and
splashproof instead of soldering additional wires into the thing etc.

Ah, the tradeoff...

By the way, several people assume the load is a light, it is not, it is
a GPS. This is isolated from the chassis which makes things easier.

Tell us more about mounting the GPS. I've considered putting one on my
garage sale motorcycle. I'm afraid the vibration will beat it to death
in short order. I have limited bicycle experience, but as I recall,
the g-forces are more intense than on a motorcycle with shocks.
I've already replaced the screen on my gps/pda once.
mike

Charge termination will be done by a micro with ADC that monitors the
battery voltage (and puts it on a display if I press a button), so I
can let the micro switch off a FET when the battery has spent a certain
time at a sufficiently high average voltage. If I find a use for it, I
could perhaps even monitor the frequency of the ripple on the battery
voltage, which is proportional to cycling speed and thus available
energy.

greetings,
Tom

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[Fred Bloggs]

Mike,




Unfortunately that's not very convenient as my battery case has only
the + and - connections of the 4-pack coming out on a DC plug, and I
would rather use the standard connector to keep things tidy and
splashproof instead of soldering additional wires into the thing etc.

By the way, several people assume the load is a light, it is not, it is
a GPS. This is isolated from the chassis which makes things easier.

Charge termination will be done by a micro with ADC that monitors the
battery voltage (and puts it on a display if I press a button), so I
can let the micro switch off a FET when the battery has spent a certain
time at a sufficiently high average voltage. If I find a use for it, I
could perhaps even monitor the frequency of the ripple on the battery
voltage, which is proportional to cycling speed and thus available
energy.

greetings,
Tom

View in a fixed-width font such as Courier.

..
.. P-CH
.. .-------+--o-->|--o---+------+---------s d----------.
.. | | | | g |+
.. .-. | |+ | | ---
.. ( ~ ) | --- +--[10K]----+ -
.. '-' | 4700uF --- | | --- 4 cell
.. | | | +----|<-----+ - NiMH
.. '---------------------+ 20V | --- (4.8V)
.. dynamo | |+ zener | -
.. 2.5-5V | --- c ---
.. RMS | 4700uF --- |/ -
.. | | +-----+---|2N3904 |
.. +--o--|<--o---+ | | |\ |
.. | | | e |
.. | [10K] [10K] | |
.. | | | | |
.. | | | | |
.. | | | | |
.. | | | | |
.. +------------+-----+------------+
.. | |
.. | |
.. | ===
.. ^ GND
.. --ON---
.. FROM GND REFERENCED MICRO --> | |
.. | |
.. GND ---- --OFF----
..

 

[Dr. Sisyphus Frankenstein]

Cool, where do I get one of those 400W bike generators?

You don't have your own and you can't afford one. The LANCE motor is
being put out to pasture after this year's Le Tour.

http://www.cyclingnews.com/photos/2005/jun05/dauphinelibere05/index.php?id=stage3/e1ec1135
http://www.cyclingnews.com/photos/2...ndex.php?id=stage3/cycling-dauphinelibere--59

I've realized dumbass Smith wanted to sell the bike, not make it go
forward. Most gen/light systems are 3 W and a nominal 6V (AC).

 

[Tom (at tomsweb.net)]

Mike,

Tell us more about mounting the GPS. I've considered putting one on my
garage sale motorcycle. I'm afraid the vibration will beat it to death
in short order. I have limited bicycle experience, but as I recall,
the g-forces are more intense than on a motorcycle with shocks.
I've already replaced the screen on my gps/pda once.

It's a PDA with integrated GPS antenna, mounted using the standard
clip-on system also typically used for battery-powered headlights. The
vibrations during normal cycling are OK, you only get quite shaken up
when going over cobblestones but the GPS doesn't seem to mind even
that. I can't tell you anything about the long-term reliability because
I haven't done many km with the GPS mounted yet.

greetings,
Tom