1967 Columbia Bicycle Headlight Mod

I am building a bike and the headlights run off of 2 C batteries and use dual e10 1.5V 0.1amp (I think…)
indecent bulbs. Is all working just not impressive. I did buy some e10 3v replacements in 50 and 100lumen range to get me started.
I am curious and looking for advice on 3v and maybe 6v rechargeable battery pack options and getting more output (I have not received the ones I bought). Not really interested in running through lots of C cells (maybe convert to enloops) and more interesting to hear what other might try (even option to charge in place like rc batt packs). Looks like I have some room in the housing. Assume others have better thoughts than mine - just want them to be really bright without burning up the lens (lumens with less temp).

Also what bulbs would be best? e10 just sit nice without ruining the original set up though anything can be placed behind the lens I guess.


Bulbs are in parallel, or series? Each bulb (1.5V) matches the cells (1.5V), so it could be parallel cells with parallel bulbs, or series cells with series bulbs.

If parallel, 1 or 2 26650s should fit, and you could replace the bulbs with LED stars with on-board 1 or 2 7135s, for 350mA or 700mA output, that should run cool enough. Even hotglue a TIR lens if it’d fit in the housing.

If series, same dealy, but just make sure the cells are protected to keep the runt of the litter from draining down too much.

Oh yeh, all this is going to require some soldering no matter what, so if you’re looking for a pure drop-in solution… meh, dunno if that’d work, but you can try.

Not sure if you can find a LED E10 bulb that runs off 1.5v, the lowest i’ve seen are 3V. I used those few times with old type square lights, but they do not focus correctly, since reflector is not made for led., those e 10s are brighter, but you’ll lose focused beam.
Your set up is a parallel bulb, parallel cells, so if you use 3.7v battery and 3v led you should be fine, those led e10 bulbs I used took li ion cell just fine. as far as cells you can use AA sized li ion they are called 14500, you use them with AA-C adapters. (AA cells are the same length as C cells)
You can use 26500 cells if you can find them, you will get much longer runtime, but like I said they are hard to find today. That is what I’d use if I did not want to modify light in any way. You could wire in a USB charging circuit, they are dime a dozen on ebay, and work relatively well.
If you want to gut it and completely redo internals, with modern leds with proper optics, larger cells, than your only limit is your imagination and your skills.

I understand what you are both suggesting. Looks like 266500 cells and a charging solution would allow the 3v bulbs to work. I was curious about running 1.5v chargeable batteries in series (maybe a batt holder suited for this) and/or getting a higher voltage bulb beyond 3v. I dont have any experience to suggest that would be a good plan, that just came to mind before I posted.

What does resonate @alpg88 was getting the optics right. So Id like to explore this vs plug and play if you could help with ideas. I am not versed in components but happy to solder, splice and fabricate as needed. The dual reflector did look good if I made use of it (the space behind repurposed) or I can drop in two modified torches wired together… Just a bit beyond my knowledge of parts to get creative.

Wellp, that’s why a TIR lens hotglued or even epoxied to a LED star would make sure the beam would be pretty clean. Lots of TIR sets come with the “shoe” the lens itself snaps onto.

What you’d do is make sure the star+lens gives the beam you want, then being that the hole for the bulb is probably big enough to fit, you put the lens in from the front, star from the back, and let the hotglue/epoxy set in place.

Without knowing the innards, where the cells fit, how the bulb is held in place, where the switch is in relation to all that, etc., no one could give meaningful advice other than generalities.

Without, say, using Fujik or something to stick on a piece of metal to act as heatsink, I wouldn’t overstress the LEDs beyond 350mA/1W, 700mA/2W at most. Compared to the paltry bulbs they’re replacing, you’ll be getting assloads more light from the LEDs anyway.

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Quick look:

ht tps://www.amazon.com/stores/page/9C5CFA37-6CB6-400F-AA4A-658A763458C5/search?ref_=ast_bln&terms=20mm%20lens

Bunch of TIR lenses, both nekkid and with the holders/spacers.

System mangled the link beyond recognition, so c&p the link and remove the space in “https”.

Yes, TIR is pretty much mandatory in this kind of modification since the bulb reflector would completely ruin the beam pattern. One thing to make sure is to offset the LED forward so the TIR surface aligns with the front of the light. If you make it recessed it would cut off too much spread, making it less useful.

Naw. For fleapower LEDs, you don’t want too wide a beam, because then it’d be so watered down as to be almost unusable.

Even the nominal 5° TIRs give more like a 20°-30° beam, just because the LED chip is a square and not a point-source.

Only in bigger lenses like for the Catapult Mini where the lens is way bigger than the chip, do you get a more concentrated beam.

That 5° TIR lens that comes with the shoe/holder would be about perfect, and it could sit flush at the base of the reflector without any of the beam being obscured.

would a power bank work as the battery holder? I have the one in the link and the outputs are 5v 2A, 9V 2A, 12V 1.5A. It takes 2 x 21700.

TY for the help. What I interpret: the TIR is a lens and that 22mm maybe is the similar size to the hole of a e10. If I get a 5 deg beam spread it should fit within my existing reflector allowing me to add 2 of them and have a nice retrofit. The led could sit in front with the black plastic shoe in back held by hot glue.

The only option Amazon option I found: (has some odd complaints)
Amazon.com (thank you @Lightbringer)

My next question would be which led? I heard not exceed 700mA/2W. Then figure out the wiring. (Newb confusion - assembly might be easier than selection)

That rechargable pack looks like a good option. I guess I am trying to figure out now what 2x led 700mA/2W would require. All in all sounds like a fun build.

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The e 10 hole is smaller than 22mm, (e10 base is 10mm diameter) Tir lens IS the reflector, you do not need yours for tir to work. leds must be mounted on an aluminum or a copper plates, the mcpcb (aka star) that led sits on, need to be attached firmly to a AL, or CO plate which will be the heatsink, hot glue is definitely NOT what you need to use. either use screws with thermal paste between the star and a heatsink, or a special thermal epoxy. it needs to be big enough to dissipate the heat leds make.
You need to use a driver to drive the led, or a resistor, to make things simpler use a linear driver, and wire leds parallel, or drive each led with it’s own driver.

Again thank you all for your time. I did some research on bike headlights which helped me to realize that there are many options to get the optics right out of the box and positioned properly. What I would like to do is get the light working and as bright as possible (bad optics) for visual appeal to complete the bike.

I received my leds and like to make these work:

  1. GutReise AC/DC E10 Bulbs, 10pcs 3 Volt Warm White E10 Replacement Bulbs Miniature Screw LED Lamps 0.5Watts 65Lm
  2. Ruiandsion 2pcs E10 Base LED Upgrade Bulb 3V COB 2W 150LM Replacement for Flashlights Torch LED Conversion Kit, White

I looked into 26500 and $36 for 2 batts and another $30 on a charger is not cost effective for my visual use case.

@alpg88 I reviewed the 14500 and the AA-C adapters - I see 2500mah LI-ON options (a few 750mah). This is easy off the shelf hope its same brightness (I can swap batts easy enough if they last an hour)

I got curious about 26650’s and any other batt pack ideas (solder). Plenty of play in the housing to bend smaller larger for 26650 if better than 14500… Just want to power best I can. Option 1 is .5W and option 2 is 2W so little confusing if that matters selecting batts.

Any advice as to which way to go and I can get them on order. Thank you again!

14500 can not be 2500mah, is you see 14500 cells that say more than 900, it is a scam. 750 is what they usually are. If you plan to stay with bulbs, get those that work with alkaline 3 cells, cuz your current bulbs will instaflash if powered by li ion. if you using e10 led than it is ok, you will lose focus but increased brightness will somewhat compensate. in any case you are not doing anything irreversible at this stage.

@alpg88 I already bought 2 types and plan to use one (replacing original e10 bulbs):

  1. GutReise AC/DC E10 Bulbs, 10pcs 3 Volt Warm White E10 Replacement Bulbs Miniature Screw LED Lamps 0.5Watts 65Lm
  2. Ruiandsion 2pcs E10 Base LED Upgrade Bulb 3V COB 2W 150LM Replacement for Flashlights Torch LED Conversion Kit, White

I am as you say doing drop in nothing irreversible. I am not going to use 26500 (its too much and will buy a bike headlight in addition).

I understand your point 14500 is ~750mah.

Should I go 14500?
I was asking now that I know these led bulbs above specifically whats the best battery? I thought 26650’s might be an option @Lightbringer mentioned so was hoping you could let me know which way to go please.

26650 has same voltage but more capacity, it will not fit without modifications to your light. they are 65-68mm long, If you modifying the light then yea, go with 26xxx, 21700, or pretty much any size, but without modifying it, 14500 is the only option for reasonable price