Old lights: conversion to LED???

Rat Rod Bikes Bicycle Forum

Help Support Rat Rod Bikes Bicycle Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
Joined
Sep 5, 2020
Messages
195
Reaction score
164
Rating - 100%
3   0   0
My Gogglefoo didn't work to find a how to on converting a conventional old style front fender light to LED. That would give a useful amount and pattern of light out of a good looking front light. Did I miss an epic thread or was it on, Cough Cough, another forum? Be Well, SS.
 
There are a lot of LED bulbs being made now that are plug-and-play replacements of legacy bulb types. It should say what the type is on the bulb (if you have it). If you don't or it's illegible, you'll have to do some searching to find its type. If it's a screw base, that should be an E type and the diameter in mm should be the number of that type, eg. you have screw bulb with a 10mm base diameter, that would be an E10 base and you'd want to search something like "E10 LED bulb". If it's the type like a male BNC fitting with pins that stick out the sides and that requires a push and quarter-turn to instal, that would be a bayonet type and that's where you'd want to start your search. If you find a replacement LED bulb, but it requires a different voltage, you can either buy a ready-made battery pack in the appropriate voltage that will fit in the provided space or wire standard letter-size 1.5V batteries in parallel and/or series as required to get the right voltage. If you need to go from 3V to 6 and the old bulb used D batteries, you could go to a 2S2P wiring using AA batteries that should fit be able to fit in the same space. Sure, the AAs have less capacity than Ds, but LED power consumption is much lower.
 
Thanks for the info. I just couldn't remember where I saw it and my goggle search didn't help a bit. You guys are great. I have an old carbide lamp that needs a slightly different home. May have to fix that. Thanks again and Be Well, SS/ AKA Packrattusnongratus.
 
I've used a few of those LED replacement "bulbs". One note is the light gets emitted differently. Incandescent bulbs emit light in all directions. Old school flashlights and bike head lights are designed to redirect the light forward using a combo of a dish reflector and a focusing lens. LEDs emit light mostly in 1 direction. Some makers add lenses directly to the LED to help spread it out. I've seen one that has an inverted cone that tries to shine it out the sides in all directions so it will work better with old dish reflectors. But all the models I've used result in a very different light beam. Mostly diffused in very wide pattern as the old reflectors and lenses are just not a optic match. For being seen on a bike, they work fine. Ditto for ambient light in a room when the power goes out or you just want atmospheric lighting. For seeing potholes in the dark, that won't do it.

I will say the batteries do last. My night stand flashlight has been going about 10 years and it's only on it's second set of AAs.
 
Also, if you put some led conversion bulbs with a direct connection to a dc wheel generator or hub generator your led will blink or strobe rather than give you a steady beam.

Good for being seen, not awesome for visibility.

Can get around it by rewiring to include a capacitor in the circuit or getting a more expensive bulb that has a capacitor built into the bulb, but then sizing could be an issue depending on what housing you're putting it in.
 
This is a good point about optics. Even with LEDs, you're going to be looking at needing a good amount of power for a good "seeing" light while "being seen" lights are easy and you can run them all day on low power. For seeing lights, I'd recommend higher voltages and light units designed as LEDs. The 12V not only makes for a more efficient and cheaper light, but also opens up automotive options. For retrofitting a fender light, I would assume a "being seen", particularly where aiming adjustment is minimal.

I have three "seeing" lights, all 12V:
USAAF bike has a 3W/5W rated cone bucket LED headlight sold as being for motorcycles that would be totally inadequate for such duty, but does well for a bicycle. The low beam setting will pick up potholes at low speeds, the high beam is probably good up until maybe 20 mph. I run it off a cigarette pack-sized liIon battery with a 6.5 aHr rating (IIRC) and it lasts about an hour and a half without ever measuring it too well.

Interrobang has an "offroad fog light" of forgotten rating, but it's definitely better than the USAAF's light. Again, I wouldn't want them for a motorized vehicle, but great for a bicycle. This runs on a ~9.6 aHr pack and lasts about the same as the USAAF's headlight. They also have a spotlight version, but as this is a low speed bike, I decided the wider beam pattern would be more suitable. Part of the reason it is better than the USAAF light is because, while the USAAF light is mounted above the front fender, Interrobang's is mounted ahead of and below the top of the front tire and the lower height and forward location definitely helps put light where you want it.

Retro Rocket has a 2006 Mazda3 projector headlight retrofitted to a 27W LED H3 replacement (or whatever size it was) running off a battery pack I cannot recall the rating for, but it's the biggest ready-made one I could fit within the body (somewhere between Interrobang's and USAAF's in capacity) and it doesn't make it an hour. The LED tries to mimic the original halogen by locating LEDs around the sides and at the end of its cylindrical body and, while it definitely puts out a good amount of light, it's not as effective as Interrobang's light despite the higher power largely because of the different beam pattern and lesser so because it's higher up and aiming isn't as optimal as it requires changing the angle of attack of the entire rocket, which is restrained by the seat height.
 
Also, if you put some led conversion bulbs with a direct connection to a dc wheel generator or hub generator your led will blink or strobe rather than give you a steady beam.

Most LED christmas lights don't have any extra circuitry to prevent the strobe effect but since AC is 60 hz, it changes so fast we can't see it. You can see the effect with a digital camera. Take a photo of xmas lights while moving the camera. With regular lights you get lines of lines, with LED's you get dashes of lights. With a bike generator, once you get up to speed, the flashing won't be noticeable by human eyes.


automotive lights! I put a LED semi truck tail light on one of my bikes. Powered by 8 AA cells. Riders behind me were claiming their eyes were burning.
 
I have a beehive truck clearance light as a tail light on Interrobang and a round trailer tail light on the USAAF bike. With the latter, I wired it up to run at brake light brightness. It is effective.
 
I have three "seeing" lights, all 12V:
USAAF bike has a 3W/5W rated cone bucket LED headlight sold as being for motorcycles that would be totally inadequate for such duty, but does well for a bicycle...
... I run it off a cigarette pack-sized liIon battery with a 6.5 aHr rating (IIRC) and it lasts about an hour and a half without ever measuring it too well.
Got any illuminating pics of your light and wiring setup @Duchess?

What kind of battery would you suggest to get like 6-8 hours?

I'm think about running 5.75 led motorcycle headlight and repurposing turn signals as tail lights, but would like to avoid lugging a wheelchair battery around if possible :bigsmile:
 
This is old—the USAAF bike (middle) has yellow film over it now. There is no flash or extra light in this room, it was taken at night and entirely lit by the bikes with the cheapest ~2015 iphone and its tiny light sensor.

Three Bikes Lights.jpg

Three Bikes Lights side.jpg

Interrobang Commons.jpg


Keep in mind that I am not an electrician, so this is what I've picked up trying to learn and it is hopefully correct, but I can't guarantee it. If anyone out there knows I'm wrong, please correct me.

I don't know what you're using for lights, so you have to figure out capacity yourself. It's not as straight forward as the simple formula: W=A*V, but it might be the only set of numbers (hopefully not too exaggerated) you'll get to work with and it should get you in the ball park. You might also get a C rating, which is the rate of charge or discharge the pack can handle, but for small LEDs, I don't think that's too important. That said, feel free to look up battery C ratings. The lesser the power of the lights or the higher the capacity of the battery, the closer it should be to matching the AH rating (I believe) since there will be less heat loss to discharge. I think that's why Retro Rocket's headlight runs on a shorter time than the advertised capacity of its battery would suggest, but my less powerful lights are pretty close. So, say you have a 12V 3W light you want to run for 2 hours. 3(W)/12(V)=0.25(A). One hour of run time would be 0.25 AHs, so to run on 2 hours, you'd want a battery of at least 0.5 AH rating or the more likely published conversion of 5000 mAh. The battery I use for Interrobang is about 9600 mAh and it's about the size of my hand with outstretched fingers. I think I paid about $30. If you get cheap li-Ion, keep in mind that they are cheap, so I wouldn't leave them charging unattended as I don't really trust their BMS and thermal runaway is a potential issue (Tesla's most important advantage is that their battery management is really good—possibly the best—and they can run the batteries down further than most because of it, increasing range as well as managing rapid high-power discharge, increasing power delivery). LiFePo (lithium iron phosphate) are a little less power dense and more expensive, but are much less prone to thermal runaway. For the motorized kayak I'm building and electric bike that will follow, that's what I'm using as power usage is much higher, but for bicycle lights I use the cheap stuff.
 
Awesome info thanks.

So a $30 LED "motorcycle headlight" from amazon claims it runs low beam at 40w, then a 18ah 12v kids power wheels replacement battery, will give me about four and a half hours of light (rounding down for poor efficiency) for about $60 and 11lbs.

Worth it? Maybe :39:

Now I'm searching to find the cheapest looking headlight that definitely doesn't meet DOT requirements or put out as much light as it claims.:21:
 
That might be the same headlight my USAAF bike has, though I thought it was lower wattage. But, it also makes sense that it would be higher than 3/5W as it's much too bright for that. Could have been a victim of translation, but anyway, it's a good light for a bicycle. It's not even that heavy as the shell is really thin. I put an external 3-position toggle switch for low/off/high beam and ran the wires to a li-ion battery pack that fits in a small saddle bag a little larger than a cigarette pack.

Anyway, that power wheel battery is lead acid, so it's heavy and longevity is poor, but they're also cheap, so whatever matches your priorities. However, if you want to put something together, you could get more capacity from a lifepo for a lot cheaper. These are small and light, each pack has their own BMS, and a $25 pack of 20 would get you 22 AH if you parallel-wired five sets of four packs wired in series. You'll also have to figure out a charger, but that shouldn't be too hard to figure out (that's my next step, myself): https://batteryhookup.com/products/lithium-polymer-3-7v-4-4ah-16-28wh-w-bms-1.

IMG_7675.JPG


You can't read the LCD, but it's 8lbs. 9.6 oz. for a 12V 44AH pack (40 cells) including the case. It's not wired up yet, but this little thing should theoretically be able to run the kayak at full power for close to 2 hours (not that I'd run it like that). However, I will find out. They have all kinds of other batteries, too, so you can figure out if something else would be better for you, but these little flat packs are a really space efficient package.
 
I run a small 12v 2600ma battery. Driver 900ma and 3 x10w leds . I get 3 to 4 hrs.
 

Attachments

  • EC610FB6-A884-4325-8B75-5D322BC2AAA8.jpeg
    EC610FB6-A884-4325-8B75-5D322BC2AAA8.jpeg
    271.5 KB
  • 8071311B-891C-4C2F-BD03-4E31025BF03C.jpeg
    8071311B-891C-4C2F-BD03-4E31025BF03C.jpeg
    209.8 KB
  • AA96E7E4-3C79-45AD-973E-EFCD819F394C.jpeg
    AA96E7E4-3C79-45AD-973E-EFCD819F394C.jpeg
    215.1 KB
  • 34368DF4-50FF-417E-B71B-6BBF8DC6E9B4.jpeg
    34368DF4-50FF-417E-B71B-6BBF8DC6E9B4.jpeg
    176.1 KB
  • 9E7E472D-24EB-44A0-9847-1B6654F0B6ED.png
    9E7E472D-24EB-44A0-9847-1B6654F0B6ED.png
    884.9 KB

Latest posts

Back
Top