proposed circuit for bicycle battery recharger

Oops, sorry, the bottom diode should have been the other way round. Messed it up when translating my schematic to ASCII. Corrected schematic:

created by Andy=B4s ASCII-Circuit v1.24.140803 Beta

This doubler circuit I found at:

greetings, Tom

Ross,

That's a standard bridge rectifier followed by a 6.2V shunt regulator.

The difference in my schematic (besides the doubling rectifier) is that there is no separate regulator but I'm using the cells itself for regulation. Part of my question is if this is acceptable for NiMH cells?

greetings, Tom

You're right, that circuit is more efficient at low input voltages because of fewer diode drops - thanks.

greetings, Tom

Tom:

I would think that "shunt regulator" does nothing to improve the effort needed to peddle the bike...

John

I am not too impressed with the way the schematic appears. What are those two devices directly across the dynamo with the GND between them?

If they are meant to be diodes then on every alternate half cycle they will place a short directly across the dynamo output.

Something like this?

That's better, should work....

What's the matter with the conventional full-wave doubler, not enough diode drops? :

View in a fixed-width font such as Courier. . . . . . . dynamo . 2.5-5V . RMS . .-------+--o-->|--o---+---------------o-------------. . | | | | |+ . .-. | |+ | --- . ( ~ ) | --- | - . '-' | --- 4700uF |+ --- 4 cell . | | | --- - NiMH . '---------------------+ --- 4700uF --- (4.8V) . | |+ | - . | --- | --- . | --- 4700uF | - . | | | | . +--o--|

Please explain the purpose of the rightmost cap???? Then explain why we need ANY of the caps????

Depending on the load vs available charge current, there may still be the problem of overcharging and the pedaling effort to just overheat the batteries.

Then there's overdischarging... mike

ahhh, I see, so the shunt kicks in, causes to great a load to be able to pedal against and the bulb is saved!!!

... are you for real, or you just don't think--possibly not understand what you read?

John

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.

HUH?? I'll need another (different) expression of the above sentence???

This has been used in motorcycles for decades...almost a century. The source is inductive, so the increased output at higher frequencies is mitigated by the inductance. If it's not enough, you can always add more.

mike

... my gawd, perhaps someone in this room will take pity on you and explain to you what an A$$ you have just made of yourself...

I might of, but ya pi$$ed me off...

John

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

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

It does if the lamp is prevented from burning out (otherwise you crash in the dark).

Pleas explain how you can double the dynamo voltage without ANY caps???? If the dynamo wasn't the dynamo, the two series caps can function as ballasts, limiting the current. But the dynamo is all wrong for this, increasing output voltage with frequency.

Right- he needs to put an N-Channel in series with the return to doubler and cut this off when the average Vbatt indicates full charge. That would be an LMV431 type circuit with zero drain when the dynamo is not charging the capacitors. Why don't you draw that up????

I wouldn't worry about that- if the lights are a safety issue then you don't want them to shut off.

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

And what is with the stupid top-posting?