DIY Bright Rechargeable Taillight?- Mtbr.com
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  1. #1
    Lost in the Trees
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    DIY Bright Rechargeable Taillight?

    I've been looking everywhere for a bright rechargeable tail light. The closest I have come to finding one is the DiNotte QuadRed. It is basically what I want, but with half the battery life. I'd build my own if it can be done with common tools.

    Here's my requirements:
    One or more red LEDs.
    High quality Li battery.
    USB rechargeable.
    8 hours life on high, steady.
    High power is 200 lumens.
    Lower power settings of perhaps 50% and 25%.
    Mountable on a standard rack 50mm or 80mm spacing, but easily detached for charging.

    From previous reading, I would guess that the USB charging and the case would be the biggest hassle.

    Is this doable with a reasonable effort?

    -Bob
    -Bob
    Tucson, AZ

  2. #2
    www.hahntronix.com
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    Unless you have a lot of the components lying around, it's probably cheaper to buy a dinotte tail-light.

    There aren't a lot of good waterproof cases that would be large enough for a decent sized battery without being pretty bulky. Finding some kind of waterproof usb jack would also be a challenge.

    If you'd consider a separate battery pack and light, you might find it cheaper to build. Since you want to rack mount it, that might work.

    -Mark
    Nimium est melior!

  3. #3
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    First a couple of other commercial options - Designshine DS 500 US $229

    Nightflux RedZone 8 AU$149 - can meet most of your specs, but not all at once.

    In terms of DIY, most of what you want is easily do-able.

    Start with the LEDs - 3 x Cree EP-E2 from P3 bin running at 0.5A gives you 200+ lumens (it is theoretically 312 but that won't happen in the real world) - eg LEDSupply US$11.50

    Pick an optic - I use a deodorant ball as a diffuser, you may want to use a conventional optic such as the Carlco elliptical spot US$1.50

    Put those into an easy2led 20mm housing US$12

    Use a GoPro mount from Vancbiker see this thread and his store US$12

    Here is just one idea- there are more ways to skin this cat.

    Wire the 3 leds in series - at 0.5A this will mean ~6.9V.

    Use an lflex driver US$25 & a decent 2s2p battery say 6200 mAh like this one US $33.95 should give you a comfortable 8 hour run time.

    Need to have a think about the USB charger though - 5v 1A is going to take a long time to charge that pack

    Parts so far are $95.95 + postage

  4. #4
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    Quote Originally Posted by find_bruce View Post
    Here is just one idea- there are more ways to skin this cat.
    This might work, you'll need to get a mounting plate made for the LEDs.

    KD dual XML light + battery. You can program the three current levels to be XPE friendly.
    https://www.kaidomain.com/product/details.S023858

    Cree red XPE triples on 20mm boards and optics to match.
    Cutter Electronics, Supplier of lowest cost leds on the internet
    Cutter Electronics, Supplier of lowest cost leds on the internet




  5. #5
    Lost in the Trees
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    Another option

    Thanks! OK, there are several interesting things to check out. I realized another way to do this however. The are numerous "portable chargers" on the market. These are essentially just battery packs that are charged from USB and they will in turn charge other devices through USB. Why not use one of these as the battery pack for the light? The light would then become a tail light head driven through a USB port.

    A USB port can deliver 5V and up to 2A and 10W. I am sure most of these portable chargers will not be able to deliver 2A/10W, but perhaps several W.

    So the question is, can a "tail light head" be developed that is driven by 5V USB power that achieves 200 lumens from 1 or more red LEDs? If so, how many Ws would be required from the battery? Lastly, there should be a way to reduce the power requested so that lower power settings can be selected.

    This has one great advantage. Now the battery pack can be detached and charged from a multiport USB charger. I would of course have to figure out a way to attach the battery pack so that it is easy to remove from the bike but is protected from water.
    Last edited by rjcarlson49; 02-01-2015 at 10:49 AM. Reason: More info
    -Bob
    Tucson, AZ

  6. #6
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    Instead of the USB you should just use a regular Li-ion battery pack. Sure the USB battery packs seem convenient and all, but you will suffer low efficiency in power usage. The Li-ion pack in the USB battery pack drives a regulator circuit to drop the nominal 7.4V of the LI=ion to the 5V for USB. Most regulator circuits operate with about 10% or higher loss. Then you have another regulator circuit to drive the LEDs. Now you have another 10%+ loss. To compensate for the wasted energy means you will need a larger capacity (heavier) USB battery to achieve your desired run time.

    The USB connectors on the USB battery I looked at were just standard USB. Not waterproof. Not even weatherproof. Long term reliability would be really poor.

    Since you are considering a remote battery pack, you should look at the tail light version of the Amoeba light. Built for many years now by MTBR forum user Scar.
    GoPro adapters for bike lights http://www.pacifier.com/~kevinb/index.html

  7. #7
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    I'm terribly saddened no-one remembers my totally awesome square tube rear light

    http://forums.mtbr.com/lights-diy-do...ss-797655.html

    I've since added a parallel wired triple red XP-E (crazy bright) and at some point in the future I'll convince someone on BLF to write me some Dinotte emulating firmware for a driver (you can get the same from DrJones, I'm just tight and don't want to spend the $9 ) so that I can change the switch out.

    Lasts forever, very eyecatching and bright, easy to recharge whenever I remember.

  8. #8
    Lost in the Trees
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    I perhaps should have said why I am sticking with USB charging. This is for bike touring. I have several devices that have to be charged and I have a pretty compact 4 port USB charger that plugs directly into the wall. Whatever rechargeable light I use, I want it to fit into this recharging system. With the profusion of portable chargers out there, I can just get a larger one.
    -Bob
    Tucson, AZ

  9. #9
    Lost in the Trees
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    Interesting and educational, but probably beyond my DIY limit. Thanks!
    -Bob
    Tucson, AZ

  10. #10
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    Quote Originally Posted by mattthemuppet View Post
    I'm terribly saddened no-one remembers my totally awesome square tube rear light

    http://forums.mtbr.com/lights-diy-do...ss-797655.html

    I've since added a parallel wired triple red XP-E (crazy bright) and at some point in the future I'll convince someone on BLF to write me some Dinotte emulating firmware for a driver (you can get the same from DrJones, I'm just tight and don't want to spend the $9 ) so that I can change the switch out.

    Lasts forever, very eyecatching and bright, easy to recharge whenever I remember.
    The only reason I didn't mention it was because then people would remeber where I got my ideas from - well that & Ofroad'bent's Crazy-bright little rear vent-light

    Have you (or anyone else) come across a USB charger for 8.4V rather than the 4.2V you used ?

  11. #11

  12. #12
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    I was just going to mention that!

    Quote Originally Posted by mattthemuppet View Post
    I'm terribly saddened no-one remembers my totally awesome square tube rear light

    http://forums.mtbr.com/lights-diy-do...ss-797655.html

    I've since added a parallel wired triple red XP-E (crazy bright) and at some point in the future I'll convince someone on BLF to write me some Dinotte emulating firmware for a driver (you can get the same from DrJones, I'm just tight and don't want to spend the $9 ) so that I can change the switch out.

    Lasts forever, very eyecatching and bright, easy to recharge whenever I remember.

  13. #13
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    usb charging for tail light

    Quote Originally Posted by rjcarlson49 View Post
    Thanks! OK, there are several interesting things to check out.
    I think browndoggadgets have a usb charging circuit or 2 that may do the trick.
    See: Parts | Brown Dog Gadgets

    Savvas

  14. #14
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    that's crazy - they sell one exact same standard USB li-ion charging board for the same price (more actually) that I can get 10 of them for off eBay. You can even get ones that have built in battery protection for not much more.

    Same goes for most of the other things I can recognise - they must make a tidy profit buying stuff super cheap off Alibaba, putting an enthusiastic spin on it and selling it at a 95% profit margin. Wish I had the energy, I'd do the same

  15. #15
    EAT MORE GRIME
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    Quote Originally Posted by mattthemuppet View Post
    that's crazy - they sell one exact same standard USB li-ion charging board for the same price (more actually) that I can get 10 of them for off eBay. You can even get ones that have built in battery protection for not much more.

    Same goes for most of the other things I can recognise - they must make a tidy profit buying stuff super cheap off Alibaba, putting an enthusiastic spin on it and selling it at a 95% profit margin. Wish I had the energy, I'd do the same
    that is how it works (almost)

    you need to physically visit shanghai, visit the electronics expos, make a deal for 10,000-50,000 unit run

    then slap it all together put a name on it and sell it. they will even give you generic boxes and headlamp straps.

    all these cheap lights are done the same way. those that are actually built well enough to last, bubble to the top eventually, like magicshine

  16. #16
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    Hi Matt,
    You are no doubt quite correct. I guess I was just pointing out that USB charging boards with sufficient output are available. I have tried trawling the net myself to look for cheaper alternatives and it all gets a bit overwhelming. I guess that's part of what BDG offers - easy access and reassurance that 'this will work with that'.
    Very inspired by your light-jiggery by the way, as well as znomit's. I've been straying off, lost in dynamo-light territory for a while which has been fun...
    For the OP, I can vouch for the effectiveness of the Design-Shine approach to side lighting - the use of a thick, projecting lens is quite effective. Also for the suggestion that you look at something made by Scar - I love my Amoeba! However neither of these lights have USB charging, self-contained battery etc...
    FWIW, my own fiddling about has favoured a much simpler approach using U-channel extrusion that leaves the whole LED/lense assembly visible from the side. I've mounted the electronics - driver or dynamo rectifier etc - either in a bit of alu tubing screwed to the back of the channel or in a separate pill canister. For tail lights I've tried various covers - pingpong balls, deodorant rollers and the translucent screw-tops off large detergent bottles. All work well with power-LEDs behind them. There doesn't seem to be any point in chasing an all-in-one design unless you want to be able to remove the light for security or for USB charging (as indeed the OP sought). Which makes most of my comments irrelevant I s'pose.
    It's probably worth remembering that - for urban riding at least - over 60% (Australian stats) of bike/vehicle collisions occur from head-on or the front quarter. We shouldn't overlook the value of front running lights too...

    The Nightflux Redzone 8, also mentioned in a previous post is an intriguing design, made up the road from where I live here in Adelaide. From a light-jigger's p.o.v it's quite a do-able approach - plastic tubing etc. I'm very attracted to it's simple engineering. It's USB charging and super bright. There's a front version as well. Could be just what the OP is after if DIY all gets too hard!

    Savvas.

  17. #17
    Lost in the Trees
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    I posted this originally because I was looking for a light bright enough for daylight for a coast to coast tour. Well, we finished the tour on Aug 30 and had a great time. DIY looked too complex so I went ahead and bought a Dinotte rechargeable light for each of us. At $189 it was very expensive, but we really appreciated having them. Every mode except Hi/Steady would run 8+ hours on a charge. It was quite bright enough to see in full daylight. The downside is that they provide about 6-8 different plastic mounts, but not one fits a normal rear rack. I had to jury rig the smallest diameter mount with layers of rubber to mount them properly. Once mounted, the lights slid easily on and off the mounts. This is really important since you need to take them off and charge them every day, at least for touring.
    -Bob
    Tucson, AZ

  18. #18
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    Bob,
    The Dinotte brackets look just like the ones that came with the old VistaLight tail lights and I've always assumed that's in fact what they are - just remanufactured, maybe using the same tools. This may explain why Dinotte don't offer a rack-plate mount. AFAIK Vista never did and it may just cost too much to tool-up anew to provide one. I have seen a simple and secure back-of-rack mounting point for these 'vista-like' brackets. It just consisted of a bit of plastic tube zip tied to the rack's mounting plate with the bracket then clamped around it. I've tried this myself with the old Vista brackets and it's very effective and lightweight if slightly agricultural. However I've also replicated the little arm bit of the Vista bracket using both alloy and stainless steel decking strip suitably drilled and mounted vertically to the rack's rear plate. Works very well - maybe this would work for the Dinotte too. It's a good trick if you are using a dyno tail light and want to supplement it with a daylight battery light. I've just made the arm extra long and bolted it on behind the dyne light using a flush-fitting bolt.

    Savvas.

  19. #19
    Lost in the Trees
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    Thanks. I will probably do as you suggest. I do already have dyno tail light mounted there.
    -Bob
    Tucson, AZ

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