bike lights

Discussion in 'Electrical' started by upgw, Jul 1, 2008.

Tags: Add Tags
  1. upgw

    upgw Guest

    i'm gonna start a lighting project. i was thinking of using those 55 watt halogen headlights you can buy at auto supply stores. do you think it is gonna be too bright. i was thinking of using a dimmer so i can control the brightness. so when it's really dark, i can use the whole 55 watts. and when it's only slightly dark, i can just barely light it up.

    would this save battery power? would a dimmer even work with a halogen bulb.

  2. likearock111

    likearock111 Guest

    One 55W halogen bulb would probably be plenty to see at night, but not a complete waste. I am using two 12V, 35W MR16 halogen bulbs and normal indoor tracklight fixtures for headlights, and I have absolutely no problem riding at night. One 55W would probably also be fine.

    A dimmer is a cool idea. You can use dimmers with 12V halogens, but they need to be specifically "low-voltage" electronic or magnetic dimmers. Personally, I'd just make my own dimmer circuit, because I really enjoy circuit design. Somebody has written up a pretty solid design that should work for your purposes here. This cirucit actually has several key similarities to the turn signal circuit design I posted in a thread earlier. If you decide to go this route and end up having any questions, just let me know.

    In general, a dimmer would allow you to use your lights for longer. The rationale here is that the circuit would require some power to operate. Therefore, if the circuit's power requirements are small in comparison to the power requirements of the bulb (like a halogen), then you'd be using power more efficiently by dialing in the optimal amount of light with a dimmer. However, if the circuit's power requirements are medium-large in comparison to the power requirements of the bulb (like an efficient, low-current LED), then adding a dimmer might not actually be worth it. In your case, though, I'd say it's definitely worth a shot.


    Also, from

    Magnetic Low Voltage Dimmers dim these light bulbs:
    (Magnetic Low Voltage Dimmers are "backward compatible". They can also dim normal, line voltage light bulbs.)
    Low voltage light bulbs - PAR36.
    MR16 - 12V and 24V.
    All kinds of normal bulbs - 120V or 130V.
    R and BR bulbs.
    A lamps.
    line voltage halogens - PAR lamps.

    Electronic Low Voltage Dimmers dim these light bulbs: (Electronic Low Voltage Dimmers are NOT "backward compatible". They cannot dim normal, line voltage light bulbs)
    low voltage light bulbs - PAR36;
    MR16 - 12V and 24V;
  3. upgw

    upgw Guest

    i was also thinking of hooking up a rear trailer light. so should i run it parallel with the headlight wire. i want to be able to turn one on and the other off if i wanted to.

    i also want to be able to flip a switch and have the rear light flash on and off. i think that is a better way of getting peoples' attention when they're whizzing by you at 60mph. i would hate to splatter my blood and guts on someone's windshield. i'd feel bad for the person and of course i probably wouldn't be able to get up to clean up the mess either.

    so how do you get the light to flash anyway?
  4. likearock111

    likearock111 Guest

    Yup - putting the two lights in parallel is the way to go for what you want. Really, though, all this means is that they'd both be connected to the battery independently.

    The flashing light deal is a little more complicated, and it can be done at least a couple of different ways. I would suggest basically building one red "turn signal" in one of the three ways listed below:

    1) Buy a flashing red light somewhere.

    2) Buy the proper type of automotive flasher for your lights (LED vs. incandescent) and wire it into your system. Adamtheha went this route, so you should probably direct questions there. The link is

    3) Make your own turn signal flashers. If you're interested in going this route, you can read more than you'd probably ever want to know at this link:

    Although the title implies that it is for LED lights only, it will handle pretty beefy incandescents (including typical trailer lights) with no problem. I'm not going to lie: it's not as easy as buying pre-made stuff and wiring it in. BUT, if you like circuits or want to learn, this would be a pretty good option for you. If you have questions here, let me know.
  5. upgw

    upgw Guest

    i was also thinking of making a battery pack out of aa or d rechargeable batteries. is this possible? the lead acid battery is very heavy. i want a lighter battery. i think i'll get more mpg this way. the standard 12v 7ah battery weighs 6 pounds.

    i also have a bunch of 18v batteries from power tools. would i be able to use those or would the voltage be too high? is there a way to lower the voltage.
  6. adamtheha

    adamtheha Member

    If you're looking for a simple 12 volt battery solution, here are a few:
    1. Wire 2 lantern batteries together in series. 2 x 6 volt = 12 volts - Caution, very low amperage, won't run too many items together.
    2. Find an inexpensive "burgler alarm" battery with charger, typically 20-30 bucks at Home Depot or elsewhere. Rechargeable and more amperage.
    3. Buy a dedicated motorcycle battery with charger and trickle charger. This will give you more power for more lights, but don't overdo it, those batteries are not cheap! If you go with mostly LED tail lights, you could wire in a 35-55w headlamp without drawing too much power. I wouldn't bother with 18v batteries, they would blow any LEDs you have, and possibly other lights too. Also would be harder to wire up a battery like that, you'd have to solder directly to it.
  7. likearock111

    likearock111 Guest

    I wouldn't go for AA or D batteries. If energy per weight is what you're looking for, go lithium. Again, the lighter the battery, the shorter the battery life (a vast over-generalization, but roughly correct). Assuming you want to run a 12V 55W halogen and nothing else, and using P=I*V (which is being generous), we're talking on the order of 4.5-5A continuously. Therefore, assuming a perfectly-charged battery, you'd need 5 amp-hours just to have light for an hour. Also, if you go the SLA battery route, you really don't want to be running them down completely (harms the battery), so a 7AH battery might be reasonable to power JUST your 55W halogen for an hour.

    You shouldn't use 18V batteries as-is. That is a baaaad idea. If you're really serious about using these 18V batteries (I wouldn't recommend it), you will definitely need a voltage regulator capable of handling the amperage you need. All voltage regulators do is convert an input voltage of V1 (18V) into an output voltage of V2 (12V in your case). ALL voltage regulators introduce some level of inefficiency into the system and waste power to some extent. Therefore, you should try to get one that is as efficient as possible. "Switching regulators" are probably what you should investigate. Check out (best place online for circuit components, period) and (limited selection, but some unique components). If you have questions here, let me know, and I'll get back to you in a couple of days (currently visiting family). My suggestion is to not go the 18V route.

    One of the few areas I'm willing to accept a significant amount of weight addition for my bike builds has been the battery. I ride at night, and I want a serious lighting system. You may only need it for early dusk riding. If so, maybe a less powerful system is in order. If this is the case, I would suggest going with a smaller wattage halogen (some people have used down to ~20 W for this type of riding and had positive results). Also, consider the net weight difference. Say another battery pack would weigh 2lbs. The net difference is 4 lbs. I don't know about you, but I'm a big enough guy that 4 lbs is only about a 2% weight change, not counting the weight of the bike and motor. I think there could be much worse ways to spend 4 lbs of weight, especially considering the potential safety impacts (seeing/ being seen at night).

    Let us know if you have any more questions.
  8. upgw

    upgw Guest

    lithium ion sounds good. do you know where i can get a rechargeable 12v li-ion battery for cheap. they give more power and weigh less right?
  9. likearock111

    likearock111 Guest

    I haven't used lithium batteries for my projects, so I can't recommend a good source. Yes, lithium has one of the best energy to weight ratios out there right now.
  10. datz510

    datz510 Member

    I am working on my own solution to the lighting question right now.

    Check out these 9 LED flashlights for sale on Amazon for dirt cheap:

    I ordered 2 of these to mount on my handlebars, With 18 high power LEDs, they should be extremely bright. I may have to take them apart and do some soldering internally to improve vibration resistance, but othr than that, for $10 and a little ingenuity, these should make for a kickass headlight setup.

    I'll post up some photos once I get the lights to compare them to known brightness lights.
  11. vegaspaddy

    vegaspaddy Member

    hi upgw,

    this is the sort of setup i use on my bike, i didnt want to mess around with the small lead acid batteries either, nowhere to mount it was my main problem.

    I already had a 14 volt battery type very simular to the one in the link although you can buy the straight 12 volt setup.

    With the battery i am able to power a double headlight 40watt 25watt combo, a rear trailer light which i use for my brake light, just as bright as any car light, i even have a scotter horn wired in. LOUD!!!!

    i commute 5 nights a week around 10 miles, my return is in the afternoon and the setup has been invaluable too me as the roads here are crazy....
    Last edited: Jul 5, 2008
  12. upgw

    upgw Guest

    that looks pretty affordable. but their li-ion batteries are expensive. they cost more than my bike with the motor. (ok almost.) so you can run a 14 volt battery on a 12volt light without frying the bulbs?

    i don't think led flashlights are gonna give me enough light. i already tried a few and they're pretty much just for being seen.
  13. worker1

    worker1 New Member

    Electra Bullet Headlight LED Chrome with Visor from amazon
  14. sparky

    sparky Active Member

    Not the Coast P7. Review is here with pics:

    Ya gotta scroll down to the last beamshot! That's why I bought this light, but it was $95 on eBay. I also bought a Coast 7732 for my mom to keep in her purse for like $32 or so, because any order over $100 from the seller knifeandlightoutdoor got free shipping. It was a pretty good deal, IMO, considering I've used Coast LED flashlights before and LOVED them. That new P7 just came out, but I'm not sure about the battery life. If I can get 3 hours at max brightness from 4-AAA batteries... I'll be more than happy with the purchase.

    I'll be posting a review when it gets here next week.
  15. sparky

    sparky Active Member

    Are you using that?? Looks pretty nice. Wish I could see some beamshots!
  16. sparky

    sparky Active Member

  17. bikejohn

    bikejohn New Member

    upgw, one of the best websites on do-it-yourself bike lighting systems that I've seen is:

    It seems to have some pretty good ideas for less-expensive and commonly available materials, and answers a lot of questions.

  18. sparky

    sparky Active Member

    I'm really enjoying the LED Lenser P7 for $95. I left the battery on overnight and it's still pretty bright. I'm expecting this to stay reasonably bright for way more than 30 hours.

    And the beam is wide. I like it a lot. The Cateye EL530 I have is not good at all for a MB. Worst $40 I ever spent in my entire life.

    The Fenix L2D and L2T are the only other lights you should consider other than the Coast Lenser P7. I like the beam pattern of the Coast light, and how the battery will last a good bit longer than the regulated Fenix lights.
  19. sparky

    sparky Active Member

    As much as I enjoy the light, I hate myself for not mounting it two days ago. I was riding at night with my crappy Cateye headlight, and totally missed this huge pile of gravel directly in front of me while turning.

    I wasn't going fast by any means, but the lower halves of my palms are torn up, my right shoulder has a nice scrape maybe about 2 inches wide (and it definitely affected both muscle and bone movement... hurts pretty bad), and a little knick right above my right eye.

    I already have scars on my face, so I'm not worried about my looks one bit. The shoulder thing effected my sleeping quite a bit, and I have to sleep on my stomach, and can't move my hands in many directions since they're wet with neosporin. Not being able to use my hands freely is the biggest killer.

    If there are any two things you should learn from this thread it's:

    (1) Get a really good headlight with great visibility for *you*, and use it!! (Golly, that ticks me off I didn't mount it right away)
    (2) Use gloves!! I see "Don't forget your helmet" all the time here, but I've seen mention of gloves like once, maybe twice. Something I'd never think about until too late.
  20. likearock111

    likearock111 Guest

    Ouch! Sending good thoughts your direction - hope the mend goes quickly!