Cat 5e cable for dynamo lights?

[syc]

I was thinking about switches for controlling dynamo lights, and the cabling necessary to support it. Cat 5e networking cable is pretty easy for me to get, and it has 8 wires arranged as 4 twisted pairs. It would be very handy for wiring to switches.

Looking at the spec, it is 24 gauge wire, conservatively rated for .577 amps - which is right about the current put out by your garden variety hub dynamo.

How conservative are these ratings? Would it be reasonable to use cat5e cabling for running a cable to a multi-pole switch? (for example, up a steerer tube)

It looks like Cat6 is made up of strands of 23 gauge, which is rated at .729 amps - though I don't know how easy it will be find cat6.

 

[Morelite]

Cat 5 should be fine. If you need to carry more current you can always double-up the wires (use two as one) and that will double the current rating.
I use pieces of cat 5 for building light engines with loads close to and slightly over 1A without any problems, though my wires are usually less than 2 inches.

 

[unterhausen]

All the cat 3/cat 5 wire I've seen is solid. I wouldn't use it because it will break. I'm using zip wire, and it works fine. I don't know what I would do about needing multiple pairs. I have some 2 and 4 pair stranded wire, but all the shielding makes it bulkier than needed.

 

[markus_i]

I wouldn't use it. I use either Schmidt cable (from the manufacturer of the SON) which is a thin (~ 5mm) flexible coaxial cable with a larger cross-section than standard RG-174 or plain RG-174 (the latter for the rear lights, since it's cheaper - and you get a variety of reasonable connectors).
If I need more conductors, I'd suggest quality microphone cable ('stage quality' cable is usually mechanically rugged, although that includes a higher overall diameter) or sensor cable (there is a family of M5/M8 sensor connectors from Hirschmann which can be had molded to a 5 meter length of very nice PU isolated, robust, highly flexible, multi-conductor cable - but that basically mandates to use also these connectors. Not a problem in itself, but that stuff comes at an appropriate price.).
The cat 5 cable would be ok for a test setup - but just because it's rated for 500 mA doesn't mean that it won't drop half a Volt over the length you're using, and there's little sense in using Schottky or FET rectifiers on the one hand in order to save some precious voltage and then using that voltage to heat the cable...

Bye
Markus

 

[Christexan]

Cat-5 can be either stranded or solid (stranded is typically for "patch" cables, solid is used for "in-wall" cables, although both work either way, stranded is much more flexible typically).

Stranded Cat-5 would be great for power usage, but I would definitely double up the strands for the positive and negative (lower overall resistance = higher efficiency). That leaves 6 strands for other uses (signaling, etc).

If not needed for other uses, use all of them for best efficiency.

 

[pe2er]

Using Cat-5 cable is no problem. I Used a flexible patch cable for the connection between my charger and battery pack.

There are four pairs of wire in there. Each pair was used for either the positive or negative lead to one of the battery cells. Charge current is 1 Amp, so the current through each wire is 1/2 Amp. Voltage drop for the 1.5m cable was around 50mV, including connectors

For detailed info, click the picture above.

On the other hand, Cat-5 cable is quite thick. On my bicycle, I prefer thinner cables. So on my bicycle I use (round, black) microphone-type cable, or red/black loudspeaker cable, both bought from a local shop.

 

[n4zou]

I use telephone line and RJ-11 connectors. It's cheap and quite adequate considering the short cable lengths required. Here is a photo of my current setup.

The box is a standard telephone jack box with a RJ-11 connector.
It contains 4 rectifier diodes and the wires are connected so the red and green wires are rectified DC and the yellow and black wires are raw AC from the dynamo. This allows me to attach any number of accessories too it. A standard AC dynamo taillight, DC LED taillight, or even batteries and a USB device. Here is a photo of the cover removed.

I also have screw type wire connectors for connecting two LED headlights currently connected to them. The single black connector and yellow wire is connected to the bottle type dynamo.
Here is a drawing of a switch selected headlight and USB circuit.

The RJ-11 connector is not shown in the above drawing. It's located between the switch and batteries. When I want to recharge a USB device I just plug in the batteries and USB connector which connects to the USB cable for the device. The 4 Ni-MH batteries regulate voltage and current for the USB device.