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.
make that 1/(2FC)
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
In article , Fred Bloggs wrote: [...]
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.
-- -- kensmith@rahul.net forging knowledge
In article , Tom (at tomsweb.net) wrote: [....]
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.
-- -- kensmith@rahul.net forging knowledge
Under the hood of a junked car.
Ah, the tradeoff...
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
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Mike,
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
View in a fixed-width font such as Courier.
. . P-CH . .-------+--o-->|--o---+------+---------s d----------. . | | | | g |+ . .-. | |+ | | --- . ( ~ ) | --- +--[10K]----+ - . '-' | 4700uF --- | | --- 4 cell . | | | +----|
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.
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).
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