DIY bike light battery options.////Picture heavy///

[photorob]

So here is my take on the DIY bike light that is so popular recently. Hopefully this will help with the heat dissipation.



The Nflex fits perfectly. On the opposite side there will be ample room for the momentary switch and battery terminal.





The heatsink was provided by a local computer repair store. They basically just gave me a few left over used heatsinks.


Here is the parts rundown:
N Flex driver
3X Q2 stars
3X optics
Heat-sink piece from old computer heatsink

With this current setup i believe I'm going to have to run atleast 11V but I am torn with the many battery options avaliable. I have compiled a small list of available battery dealers. Hopefully others can help extend this list.
LINK 1
LINK 2

 

[AndyTiedye]

Added to Bike Light Thread Links

 

[sfCyclotourist]

Nice. How did you make the cuts in the square Al tubing? I just finished my light using a similar housing design where I did all the fabrication by hand using a hacksaw and files, and my results weren't as square and clean as yours appear to be.

 

[photorob]

I basically just used a hacksaw and a file. Slow and steady. Patience always pays off. I am still confused on what to use for my battery. Well maybe a little more confused on which connections to used. I would love to have a female jack on the body but I also would like it to lock in.

 

[photorob]

Any connection ideas out there?

 

[sortafast]

For Connectors, I would Just go and get the bike light wiring kit thing from batteryspace. It seems like a decent deal. And its weather proof. I got some sample splash proof connectors for a bike light project I am trying to get going. They arent quite the same, but the work pretty darn good.

 

[nightrider]

Nice job photorob! I hope the heatsink is worth the effort of the extra cuts and reduced space to put stuff in the light body. If you keep moving air over the light (like ride your bike while the light is on) it is really unnecessary. But a cool look, and innovative alteration anyway!

I use a female, size M connector from Radio Shack and it's male counterpart on the battery wire. I've never had it fall out. Don't know how waterproof it is, but I've ridden in light rain several times without problems.

You're gonna need more than 11v with the 3x Cree and the nFlex. I'd go for 14.4v NiMh or 14.8v Li-Ion pack. Either one of these will work great.
BatterySpace
All-Battery

-Allen

 

[photorob]

BatterySpace

What do you think the runtime difference will be between this battery and that battery.

LINK

Also is the supplied 4 foot cord enough to get from my head to the bottom of my camelbak, or do I need an extra 4 feet.

 

[aljsk8]

hi

i too am building this light...

i need to know if 14.4v of 2200mah aa cells would be ok for this setup?

what could i expect for runtime?

thanks

Alex

 

[chris_m]

You need at least 11.5V to 12V (depending on the Vf of your LEDs) to keep an nFlex in regulation with 3 Crees. This doesn't mean a 12V pack, since that is the nominal mid charge figure, and such a pack will be only 10V when it is run down, hence out of regulation. As already mentioned either a 14.4V NiMH or 14.4/14.8V LiIon will work fine, since either of those runs down to 12V.

Of course the alternative is to use a boost driver instead, in which case you can use a much lower voltage battery (eg a 7.4V LiIon). Either a Fatman, or if you want something similar to the nFlex you'll have to wait until George fixes his Maxflex (in the meantime I'm rolling my own uC controlled boost driver - not taking orders though, as it's strictly small scale production and I also don't want to step on George's toes).

14.4V of NiMH will be fine. Expect about 2 hours at 700mA, 1h20 at 1A from 2200mAh (I recommend the former, as I'm not convinced the small increase in brightness is worth the decrease in runtime).

Oh, and I like the added heatsink - the cooler you can keep the LEDs the better.

 

[aljsk8]

sorry to keep hijacking

would there be much difference in 2 cree at 1000ma
and 3 cree at 700ma

thanks

 

[RustyKnee]

Nice looking light. The heatsink will definir=tely be handy when stationay for any period.

sorry to keep hijacking

would there be much difference in 2 cree at 1000ma
and 3 cree at 700ma

thanks

Looking at my speadsheety 3 at 0.7 should be about 20% brighter than 2 at 1amp and have the same overall power

Stu

 

[eebowler]

Any connection ideas out there?

Just found THESE at batteryspace.com

 

[photorob]

BatterySpace

What do you think the runtime difference will be between this battery and that battery.

LINK

Also is the supplied 4 foot cord enough to get from my head to the bottom of my camelbak, or do I need an extra 4 feet.

Just to reiterate.

 

[RustyKnee]

Just to reiterate.

In this case the 2nd bat will run 5200/4000 times longer 1.3 times

estimated run times

4000mAh

14.8V*4Ah= 59.2WattHours

5200
14.8*5.2=76.96

3 Crees at 700mA is about 7.5Watts

59.2/7.5=7.9Hours

76.96/7.5=10.26Hours

this ignores efficiency of the driver....for 80% multioply times by 0.8

Stu

 

[nightrider]

Just to reiterate.

Rob, I get about 5 hours with the 4A, so you'll prob get another 1.5 hours with the 5.2A. (approx 6.5 hrs) assuming you run your LEDs at 1A. Note: you won't get full LED brightness for the total amp-hour rating of your battery... from my experience.

Yes, the 4 foot battery lead is perfect from the helmet light to the Camelback.

 

[nightrider]

hi

i too am building this light...

i need to know if 14.4v of 2200mah aa cells would be ok for this setup?

what could i expect for runtime?

thanks

Alex

Should get you about 2.5 hrs.
Yes, that would be fine if that's enough runtime for you.

 

[aljsk8]

is there anyway of waterproofing and electricly isolating the circuit boards before you put them in the tubing - water will get in and the circuit touching the alloy cant help

some ideas i had were cut a balloon and put the circuit in then glue it closed (around the wires)

melt wax all over it

or is there some kind of spray?

let me know if any of this would work

Alex