Bikelight idea, advice needed on how to realize it

[Coop]

I recently bought a recumbent bike (Challenge Hurricane Sport USS) which came equipped with a SON hub dynamo. I'd like to make a nice light for this bike and have a few ideas, but some advice is always welcome.

First of all, I'd like the light to be fairly small, as on my recumbent it will be mounted on the part that would be called the bottom bracket on a regular bike, so it is in between the cranks.

Now one of the ideas I had was to use a flashlight bezel that is compatible with the P60 style lamp assemblies, so I'd have a choice of dozens of different LAs to choose from and upgrading will be easy as I'd just have to replace the LA as better versions come out.
Then have one of the modders here on the forum make me a sort of screw in plug that screws directly into the bezel to keep the LA in place. Mounting could be done by screwing a bracket between the bezel and endcap.
I was planning on using a good LED drop in like the Malkoff or the Wolf Eyes that I already have. But of course I can't just hook these up to the SON directly.

I could hook it up using a bridge rectifier and a voltage limiter, but I was thinking about powering it from a Li-ion cell/pack and have the SON charge that cell/pack. This would have a few advantages. First of all, the light will stay on when I stop the bike, which is a big plus on the safety side. Another advantage would be that I can switch off the charging circuit, reducing drag on the hub and still be able to use my light. I'd like to have the option to power the light from the hub too for when the battery dies. Another option I've been thinking about is using the DX drop in with wide voltage range (http://www.dealextreme.com/details.dx/sku.6090) with just a bridge rectifier between it and the SON, it would make a nice temp solution until I get the rest of the system figured out.

So what do I need help with?
- Who can make me the mentioned endcap and how much would it cost?
- What do I need to make a Li-ion cell/pack charge from my SON hub?
- Am I overlooking anything?

 

[n4zou]

I homebrewed exactly what your wanting! I ordered a 1-watt Luxeon star and matching Fraen elliptical optics and mounted it in a 1-inch PVC pipe coupler.

The outside diameter is about 1 1/8 inches. That will easily fit on your bottom bracket between the cranks.

I selected the 1-watt LED as it only draws 350mA. Your SUN hub will provide 500mA of current. Add a super bright LED (or several standard LED's) as a taillight consuming around 35 or 40mA and you have around 120mA of excess current recharging the batteries as you pedal along. This will keep your head and taillights running when you stop or you're in very slow (5 MPH or less) traffic. You don't really need an LED driver. The batteries will regulate the voltage output of the dynamo and provide a place for the excess current to go. Just carefully selecting resistors and inserting them between the headlight LED and batteries will work fine. I just put a 5.1-ohm resistor in line with an amp meter to read the current and then paralleled 50-ohm resistors until the current read 350mA with a fully charged batteries and my speed was 14 MPH, which is maximum output of the dynamo. Here is the circuit I use.

Here is a photo of my bottle dynamo.

Here is the bridge rectifier attached to the rear of the front reflector bracket.

Here is the front terminal strip with headlight resistor and wires leading to the headlight, S1, rear terminal strip, and a 470mF capacitor to be used with the LED's just in case the batteries fail and become unusable while touring.

Here is a photo of the rear terminal with taillight resistor and batteries. I also use a GPS receiver and I made a power and recharging cable to operate it during daylight hours with the LED's turned off. The 4 NiMH batteries perfectly simulate the power available in a standard computer USB port. I cut up a USB extension cable and hooked the RED positive and Black ground wires to the batteries and simply connect the USB cable for the GPS unit to it.

 

[Coop]

You have a really nice bike there! Specialized crossroads... Looks like an early 90's model I think? I have a 1999 Specialized rockhopper myself. Used to have an older steel framed rockhopper, which was really nice, but it was stolen... twice...

While I think the schematics you posted might come in very useful, and you have a very nice setup on your bike, it's hardly 'exactly what I'm wanting'

I'm not going to power a taillight from the hub/li-ion setup, as the bike came with a battery powered taillight that has some good bright 5mm LEDs that will run forever on a set of batteries.

I have thought of a similar setup as yours, but I want to use a P60 style LA or LED drop-in to make upgrading easier and it would also add the option of keeping a spare available, instead of soldering in a new LED. It might be harder to set up at first, but the ease of being able to toss in a different LA whenever I want is worth more to me.

And another thing, I don't think a setup with lots of exposed electrical bits will work very well in the dutch climate, it gets kind of wet here all year round.

Thanx for your help!

 

[Calina]

I recently bought a recumbent bike (Challenge Hurricane Sport USS) which came equipped with a SON hub dynamo. I'd like to make a nice light for this bike and have a few ideas, but some advice is always welcome.

First of all, I'd like the light to be fairly small, as on my recumbent it will be mounted on the part that would be called the bottom bracket on a regular bike, so it is in between the cranks.

Now one of the ideas I had was to use a flashlight bezel that is compatible with the P60 style lamp assemblies, so I'd have a choice of dozens of different LAs to choose from and upgrading will be easy as I'd just have to replace the LA as better versions come out.
Then have one of the modders here on the forum make me a sort of screw in plug that screws directly into the bezel to keep the LA in place. Mounting could be done by screwing a bracket between the bezel and endcap.
I was planning on using a good LED drop in like the Malkoff or the Wolf Eyes that I already have. But of course I can't just hook these up to the SON directly.

I could hook it up using a bridge rectifier and a voltage limiter, but I was thinking about powering it from a Li-ion cell/pack and have the SON charge that cell/pack. This would have a few advantages. First of all, the light will stay on when I stop the bike, which is a big plus on the safety side. Another advantage would be that I can switch off the charging circuit, reducing drag on the hub and still be able to use my light. I'd like to have the option to power the light from the hub too for when the battery dies. Another option I've been thinking about is using the DX drop in with wide voltage range (http://www.dealextreme.com/details.dx/sku.6090) with just a bridge rectifier between it and the SON, it would make a nice temp solution until I get the rest of the system figured out.

So what do I need help with?
- Who can make me the mentioned endcap and how much would it cost?
- What do I need to make a Li-ion cell/pack charge from my SON hub?
- Am I overlooking anything?

For the electronic part, here are a few threads you might be interested in:

http://candlepowerforums.com/vb/showthread.php?t=172636

http://www.candlepowerforums.com/vb/showthread.php?t=175923

http://www.candlepowerforums.com/vb/showthread.php?t=174557

 

[n4zou]

You have a really nice bike there! Specialized crossroads... Looks like an early 90's model I think? I have a 1999 Specialized rockhopper myself. Used to have an older steel framed rockhopper, which was really nice, but it was stolen... twice...

Correct! It is an older bike but perfect as a loaded touring bike. I put 7,238 miles on it last year. I have 5,793 so far this year. I always reset the odometer Jan 1, as the odometer will not clock over 9,999 miles.

While I think the schematics you posted might come in very useful, and you have a very nice setup on your bike, it's hardly 'exactly what I'm wanting'

I'm not going to power a taillight from the hub/li-ion setup, as the bike came with a battery powered taillight that has some good bright 5mm LEDs that will run forever on a set of batteries.

I also run Blinkies front and back as additional "be seen lights". My system needed the taillight to use some of the current not used by the headlight so I could keep the excess current recharging the batteries to the suggested slow recharge rate of 120mA. You could purchase one of the new Luxeon Rebel LED's that produce 80 lumens at 350mA and can be operated at up to 700mA of current. This eliminates the need for the taillight. It also eliminates the battery as an excess current sink but your headlight will go out when you stop moving or your going very slow like up a steep hill.

I have thought of a similar setup as yours, but I want to use a P60 style LA or LED drop-in to make upgrading easier and it would also add the option of keeping a spare available, instead of soldering in a new LED. It might be harder to set up at first, but the ease of being able to toss in a different LA whenever I want is worth more to me.

I purchased my Luxeon 1-watt LED and it's matching optics from this link.
http://www.luxeonstar.com/index.php
I used hot glue to attach a heat sink made from scrap copper sheet metal to the optic lens holder. The LED star is held in place by pressure between the heat sink and holder legs. It's very easy to simply pull the hardened hot glue from the heat sing and remove the LED for an upgrade. The plastic PVC pipe coupling cost me less than $1 at the hardware store. Here is a photo showing what the holder, star, and heat sink look like assembeled.

My heat sink is round and just fits inside the PVC pipe coupler.

And another thing, I don't think a setup with lots of exposed electrical bits will work very well in the dutch climate, it gets kind of wet here all year round.

Thanx for your help!

Everything is low power so there is no problem with the connections getting wet. Also it's just passive components so none of it will be damaged if it gets wet. My Headlight however is sealed up pretty well. I've been caught out riding in some serious downpours and every thing got very wet. I did turn on all my lights so traffic could see me and everything worked just fine while being drenched with rain from above and below from the pavement.