Hi all

29/9 : I have been looking around at getting some decent lights for night riding but have been scared off by the costs...anything from R1500 (2nd hand) to R7000 (top of the range brand new). This has got me thinking of making my own.  I have looked around on the net and see a few people have tried this before.

So here goes..I will get the thinking cap on. Obviously I would like to keep costs down as much as possible. I am looking more at functionality that aesthetics here..so don't expect a plush looking set of lights lol. Also going to investigate both bar mounted vs helmet mounted. Please feel free to join in and make comments/suggestions or just tell me I am on the wrong track !

30/9 : After lots of googling and searching, I have realised that this DIY business is more detailed than assumed. Still going ahead though..its fun. Have a look at these 2 links and you will see whats possible :

www.thehubsa.co.za/forum_posts.asp?TID=22510&PID=410823#410823

www.thehubsa.co.za/forum_posts.asp?TID=33357

It was about 2 months ago that I first started thinking about making my own lights. At that stage it was just something to do when it was raining outside. I got myself the following :

- 1 x 50w halogen globe (downlighter type)

- 1 x pvc 45 deg elbow

- some glue

- some wire

- a 12v motorbike battery

- a toggle switch

I thought that this would be easy...cmon..just glue the globe into the pipe, connect the wires and switch to the battery and its done. And it was...easy. I had a serviceable light ...for like 20 min ! I didnt know about Volts vs Amps or battery life vs brightness or anything else that I should have. My "bright" idea suddenly got a lot dimmer ! The following pics are of the first attempt...

Now here we have to start getting mathematical (not my strong point ! )

To determine how long a battery will last and how bright the light will be, we have to look at Wattage (W), Amperage (A) and Voltage (V). Wattage is the strength of the globe..the higher the wattage the brighter the globe.  Voltage is how much power the battery puts out..but higher voltage doesn't necessarily give better light. Amperage is how much power the light will draw from the battery...the lower the amps the better. Because Voltage is not guaranteed or constant, a 12V battery is calculated at 10V.

I was using a 12v 3 A battery with a 20W halogen globe.  The formula W/V = A is used to calculate how many Amps the 20W globe is pulling from the 12V battery. Therefore...20W/10V = 2 A. This is therefore the load that the 20W globe is pulling from the battery. The load will determine how long the battery will last. If I want the light to run for 2 hours, this means that the battery must be rated at at least 4 A (load x time ie 2A x 2 hours = 4 A). The battery is rated at 3A..therefore pulling 2 A, a 20W Halogen will last 1.5 hours before being dead..but also remember that the light will just get dimmer and dimmer until it goes dead, so in fact I would hopefully get just over an hour of light out of the battery. This is assuming that the battery is fully charged and resistance is minimal. Kinda sux hey ! A 20W globe gives some decent light up front but doesn't really shine far enough to identify terrain about 10 meters away. The weight of the battery is also pretty hefty and would either have to be securely mounted on the bike frame or carried in your hydropack. Also worth noting is that once the air temp drops below 25 deg C, battery output also diminishes (and since its night riding this easily happens).

Increasing the Halogen bulb to a 50W makes a big difference to the brightness of the light but also increases the Amps drawn and drastically decreases the lifespan of the battery (50W/10V = 5 A and using a 3A battery means I would be lucky getting 30 min of usable light)

So this is where I find myself at the moment. I have now been looking at LED lights as they pull a LOT less Amps and have much longer lifespans (which either means lighter batteries or longer battery time). There are disadvantages though..they are more expensive, have to have dedicated controllers (buckpuck) and take more modifications to turn into MTB lights. The best source that I have found so far is www.rabtron.co.za. I am thinking of a monster set up like show in the links at the beginning of this article ...:)

01/10 : Found another article that looks interesting wrt helmet mounted lights.

http://www.thehubsa.co.za/forum_posts.asp?TID=22510&PID=459293