…Okay, so not exactly a Tron Bike. But I had a couple of lengths of EL wire to play with and a poor imagination. After a lengthy trawl on Google I decided the easiest way to utilise it would be to outline my bicycle. My partner’s bike was wrapped in EL wire which, whilst glowing like the Blackpool illuminations, didn’t look particularly special in my opinion (sorry, dear). I played about with the length of wire I had and some tape and decided that outlining the frame had a nicer effect than spiralling around it.
The next task involved deciding on a way to attach the wire to the bike. Some “caterpillar” grips had been left with the wire – rubber grips with a sticky backing, into which the EL wire clipped. Unfortunately, despite carefully cleaning the frame with meths before applying the caterpillars they soon detached. I was looking for a method of attaching the EL wire without cable ties, which were messy. I didn’t want anything permanent, or that might damage the paintwork too much should I need to remove the wire for any reason. I settled on Sugru, which claimed to stick to almost anything. It did for a time, but whether I was too stingy with how much I applied or whether the paint was inappropriate as a surface I don’t know, but a good third of the blobs of Sugru soon either detached or broke up.
I then had a stroke of genius. I have no idea where it came from; an overheard conversation? Something I’d read on the internet? But I decided to try hot glue. Now, the internet suggests that EL wire doesn’t respond well to heat and I can quite happily believe the paint or plastic would be easily denatured by hot or prolonged exposure. A brief test on the end of the wire indicated however that the short exposure to the molten resin didn’t appear to have an effect on its ability to glow, or the colour emitted. Given the metal frame would act as a heat sink I was confident that the wire would not be damaged during application. Two weeks later the stuff still sticks and the EL wire still glows, so I appear to have guessed correctly.
Meanwhile, I was trying to work out the optimal way of powering the EL wire. The obvious choice were Li-ion batteries, which are reasonably compact and relatively light (in comparison to a lead acid), but I didn’t know which transformer I had or how much power it would draw. My dad provided the answer; on a rare visit home to my parents we sat down with a multimeter, the EL wire and transformer and an assortment of batteries including some 1.2V AA, a handful of rechargeable and single-use 9V and an old 12V motorcycle battery. We used the mutimeter to measure the voltage provided by the batteries and applied them to the transformer. Obviously the motorcycle battery worked well. To be honest we didn’t even try the AA batteries, as we didn’t have any way of tying a number together. The 9V batteries provided some interesting results, though. The brand-new single use batteries powered the wire nicely, whilst the rechargeable batteries failed to make even a faint glow. Measuring the voltage of the batteries showed around a 0.3V difference between the two groups; the single-use batteries provided around 9.6V, whilst the rechargeables varied between 9.30 – 9.35V, indicating that the wire could be powered successfully from a minimum of 9.6V supply.
The next task was to work out how much current the wire was drawing, and whether this varied between the 1m and 3m lengths of wire I had to hand. In practice there was very little difference; both drew around 0.2A. Coupled with the knowledge that the wire can be supplied by a 9.6V battery, we determined that eight AA batteries would be sufficient to power the wire for, theoretically, anywhere near 10 hours (assuming 2.9Ah batteries were used, allowing for any resistance or wasted energy – the transformers squeal quite nicely at a frequency above 12,000Hz, as my dad was blissfully unaware when I mentioned it). A quick trawl on the internet identified some 2.9Ah AA batteries at around £5 for 4, so I purchased two packs along with a couple of battery holders with built-in switches (about £1 each). I removed one of the switches, wired the holders in series and finished by unceremoniously taping the two together. A terminal block was attached to the two dangling power wires and I inserted the first transformer, switching the power to *on*. Result! As expected, the EL wire illuminated with an eerie glow. I then wondered if two transformers could be run off the same battery pack and added a second one in parallel to the first by screwing an additional transformer into the terminal block. THis gave me an additional glowing wire. Since then, I’ve discovered that you can buy splitters which attach between the wire and the transformer, allowing multiple wires to be powered by one transformer instead of the multiple-transformer setup I have. I may eventually get around to purchasing in order to reduce the number of transformers I’m using. But for the meantime, the entire pack – batteries, transformers and dodgy wiring – fits nicely into my saddle bag with room for a puncture repair kit, my handy set of Allen keys and a couple of nitrile gloves.
And that’s it! The batteries remove easily from the holder and pop into a normal charger and so far I would guess I’ve had around 4hrs use without a charge. I’d like to get my hands on a couple more battery packs, or find a more compact, lighter way of powering the wire (even for a short period of time) so as to completely outline the bike in blue, as I’d like attach two power packs and transformers to the wheel hubs in order to illuminate the rims. It has been done by others before me (google it!) and I’ll most likely lose interest and move onto another project before I get around to doing it (maybe I’ll go back to my Alethiometer table?!). In the meantime it’s fun to think about. Having been through Google images I also like the idea of integrating EL wire into clothing, such as on a motorcycle jacket or corset (something I previously thought about doing with Lilypad stuff and some conductive thread) and maybe if I had the time, money and a slightly less distracted mind I’d do all of this. But for now, I’m satisfied with my Tron Bike!