Dynamo Regulator Charger Circuit for full-time lights...

[duivendyk]

You mean using a hub dynamo?.Yes it would work, you might get up to 0.5 Amp out of it,current speed dependent though if too much charge current put series resistor in lead to battery (5-20 Ohms,) or stick a series string of LED's ,or a parallel set of these strings across the batt,to bleed off excess current.Around 14 + V batt. voltage when fully charged.A lot of LED are 3-3.5 V units (they act as sort of like crummy zeners) so 4 of them in series is about right for 14V.If need to bleed off more,more strings.You could use them for day-time& rear lights.

 

[jtmiyake]

You could charge a 6V battery with a 4 diode bridge rectifier circuit (preferably Schottky diodes) and stick a 7V 2Watt zener diode across it to prevent overcharging and/or a bunch of 2x 3.5 V LED's in series/parallel.When the LED's begin to light up,the battery starts getting overcharged.That's not all that complicated.

I went to RadioShack and the lowest voltage rectifier they had was 50V, 4A full bridge rectifier. It was cheap so I thought I'd give it a try. No lights. So should I just build my own rectifier with 6V/3W diodes?

 

[duivendyk]

That's strange,did you hook it up correctly?.Do you have multimeter,digital or analog?.Is it labelled clearly?.If you have digital one, checking continuity (on ohms) can give you faulty readings because test voltage may be less than 6V.If you have a "diode" test position, that should be OK.Check first if dynamo puts out ac.Put meter on ac volts,connect&spin wheel,should get 6V or more.Did you use LED's to check output?.If you hook it up wrong, no light,one LED takse 3-4 V.more in series n times as much .Also POLARITY sensitive(acts as 3V or so zener if reverse biased,but NO light).Also check dc output from rectifier should show a few volts at least,but reads average not peak which matters a lot when charging battery.

 

[jtmiyake]

That's strange,did you hook it up correctly?.Do you have multimeter,digital or analog?.Is it labelled clearly?.If you have digital one, checking continuity (on ohms) can give you faulty readings because test voltage may be less than 6V.If you have a "diode" test position, that should be OK.Check first if dynamo puts out ac.Put meter on ac volts,connect&spin wheel,should get 6V or more.Did you use LED's to check output?.If you hook it up wrong, no light,one LED takse 3-4 V.more in series n times as much .Also POLARITY sensitive(acts as 3V or so zener if reverse biased,but NO light).Also check dc output from rectifier should show a few volts at least,but reads average not peak which matters a lot when charging battery.

I was thinking my problem was trying to use to a 50V rectifier and that I needed more voltage to get it through the diode. So you think it should still connect the phases to DC current even at that high of a rating with so little input? My digital continuity meter is a compact one so it does not put out much voltage. I double checked my connections. There was only one lead labeled as AC but there was a + and a - lead. I connected the positive and negative leads to the light and the AC and non-labeled leads to the dynamo. I may have got the rectifier too hot when soldering leads but it only felt warm to slightly hot by touch. I may have to set up a test bench with the wheel connected to my drill.

BTW - I do not know much about these electronics but I am an engineer so I can learn pretty quickly. I at least figured out how I can make my own rectifier (4-diodes - how complicated is that). I have not taken the next step of charging batteries. Thought I'd see if I could get DC current first.

Another BTW - the light works pretty well at 10mph but I'm worried the AC current is going to cause my bulbs to go quickly. I've been riding a couple of days now with the light on and all seems ok so far.

 

[duivendyk]

No ,that rating is the max reverse bias voltage the diodes can handle before they will break down in the REVERSE direction,you are way below that with your dynamo.It looks as if you connected it up correctly.OK put leads on the ac (unlabeled inputs).and put a dc voltmeter between +and -.Simple way to test rectifier.Connect the ac leads to a car battery,you should get around 11V at the dc output,switch the ac leads around,should get same voltage again with the same polarity. If that is the case your rectifier is OK.