Tesco Cree LED Helmet mounting - GEEK ALERT!

Mikey joe

Apologies in advance for another Tesco Cree thread and also the geek content of this post.

Read on at your peril.


I modified my tesco cree so I could mount it on my helmet in a similar fashion to that posted by forgotrafe a few weeks ago. I added a few things which may improve the design.

Firstly a few observations:
1. I think the light is great for a dark commute but not good enough for night time off roading.
2. The modification reduces the wight of the torch by about 40g an also spreads the wieght around a bit better which makes it more comfortable to wear on your head.

This is how I did it:

Materials:
torch
2 x AA battery box with switch
heat shrink tubing
Old 26"x2 inner tube
Old bracket for a rear light or similar
Some velcro
Silicon sealant
solder and iron
cable tie
Araldite or urethane glue

Firstly I made waterproof bag by cutting and folding a piece of cut inner tube to the correct shape. Think of a bag with a fold over lid. I glued this at the base and used velcro so that the fold over lid could close. I pierced a hole in the top of the rubber bag. This was a nice snug fit for the battery box.

1. removed the head piece of the torch (the bit containing the LED module.)
2. run the wires from the battery box through the heat shrink tubing.
3. Put the battery box in the waterproof bag and run the heat shrink covered wires through the hole you pierced in the top of the bag.
4. I unscrewed the head unit and threaded the wires from the box through the metal casing.
5. Remove the spring from the LED module with a wire cutters. Solder the wires to the LED unit. (Remember to do this the right way round. posituve to positive etc. )
6. Reassemble LED unit and head unit.
7. Fill back of head unti with silicon to waterproof headunit

8. To attach to helmet I used very strong velcro to hold the battery case to the helmet.
9. To attach the LED /head bit I cut a band from an old inner tube and used that as a shim and used the old cateye bracket to attach to the helmet with velcro and a cable tie.

Works like a dream for me.


Photos here

http://www.flickr.com/photos/9311482@N0 ... 001729970/

cougie

That is very impressive.

I just went for the slacker approach - hairband and a bit of rubber underneath to cushion the torch.

moggy82

nice work, while it was apart, did you try over volting it by using 3 batteries, it would be good if we could know how it affects the light. because then you could run 3x2 batery pack in your bag.

FSR_XC

A bit concerned on how high above the helmet the light is.

I would have mounted it further forward and angled the bracket accordingly. Similarly, with the battery pack - why not mount it at the back of the helmet.

I am being quite picky here. I do think it's an excellent job and a darn sight better than what I've done:

Mikey joe

cheers

Hi moggy - no i didn't as I didn't want to burn the LED - but could you not wire the batterys up so that you could use either 2 x 2AA boxes or a 4xAA box and run the light for twice as long without over volting it.?

The way I figured was that it was neater and easier for me to carry the spare batteries in my pocket. Also the 2xAA box fits into an inner tube so well it would be a sin to not use it.

It's been running for about 2 hours now on the original tesco alkaline batteries and going well! I'll stick some 2100 mAh Hybrios in it when these are dead.

As an aside this mod eliminates the problem folk have had with rechargeable batteries not fitting well.

WRT FSR's comment. This is a fair point. The reason was that these were the points where the surface was the helmet was "flattest" and so gave the best point for attaching via velcro. It'd be a simple enough job to move them. The light increases the height of the helmet by 65mm. I rarely go under anything low enough where I'm glad of that much extra clearance. .

Steve_b77

Not a bad job even if I do say so myself, but please tell me the picture is miss-leading because it looks like you've pierced the polystyreen shell to feed the cable tie through.



Correct me if I'm wrong, but if you've done this I really hope you never land on your head as you've seriously affected the integrity of the helmet :shock:

Mikey joe

Hi Steve

Yep I have pierced the polystyrene. There's a gap of about 2-3 mm. I'm not overly worried though. My way of looking at it is that while it would invalidate any warranty etc I don't think it will affect the inegrity significantly as it is polystyrene. It's not a hard shell helmet. The effect of me landing on my head would be 27mm of polystyrene cushioning as opposed to 30 mm, which might make a difference just not a huge one (I hope).

AFAIK (and I'm often wrong) the structure of polystyrene is not as critical to its function in the same way as for example. carbon kevlar. I have a carbon kevlar kayaking helmet and wouldn't dream of doing anything to modify it lest I affect its function.

interested to hear opinions on this

Steve_b77

I have been told that as soon as you undermine the integrity of a polystyreen shell it should be replaced.

Mikey joe

Hi Steve,

I've heard that too. but I'm an awkward so and so - I tend to look for reasons in why folk say that. I understand that some materials gain strength from how the material locks together carbon fibre for example. However I thinkpolystyrene is used in helmets because it is very light and strong for it's weight but essentially I understand that its just there as cushioning. So that if I land on my head the polystyrene will compress and protect my head. My kayaking helmet on the other hand will not compress (much). What that does is absorb the impact and spread it around the surface of the helemt lessening the pressure. There is also some cushioning in it but that's only to help out it's not the main thing. So if there is damage in some part of my kayaking hlemet it will impair its ability to spread the force around the helmet. With the bike helmet this is not so important as there is no "communication" through the nmaterial around the helmet.

The crux of your point is valid. By removing 3 mm of material I am reducing the amount of force I can tolerate at that point. But I don't thinkk that it affects the integrity of the helmet as awhole.

By the way I am not a material scientist etc. This is only my opinion. I am happy to be proven wrong.

Mj

moggy82

I may burn the led out but its only a bit of a project for me as i have a mte18650 and hope V1. i like to play with lights, have you had any joy with adjusting the beam to give a slightly broader beam pattern. Im planning on modifying a C cell one rather than a AA one once i get a bit of free time. I'll keep you posted.

forgotrafe

Glad I was some inspiration

Mikey joe

It'd be good to hear how you got on moggy.

Yeah it was your plan forgotrafe - I only tweaked a few things.

Cheers

forgotrafe

Mikey joe - No worries, glad someone appreciated me taking the time to post some pics. Good tweaks though I like the battery box cover. I can see me using that idea

marks65

Here is my modification to the Tesco 2xAA bike torch.

Remove the head and base and bin the central barrel.

You'll need:
DC connector and plug - http://www.maplin.co.uk/Module.aspx?ModuleNo=1407
Araldite
Wire, Soldering stuff.


Prepare the base

---

Remove the switch from the base (use pointed pliers to unscrew the switch and its circuit board)
Bin the switch.
Drill out the metal switch plunger thingy to the same diameter a DC power connector.
Push fit (+ bit of super glue) the DC connector into the plunger. Araldite the plunger back into the torch base (avoid getting Araldite into the DC connector.)

Prepare the head

---

Without the battery to push the LED it rattles in the head. So, unscrew the head and Araldite the LED in place. (Just a bit at the contact points around the round aluminium base of the LED and the white plastic head should be all that's needed to hold it in place)
Cut the spring down to only a few mm - just enough to solder the wire to.
Wire the DC connector (-) to the remains of the spring and the (+) central contact point.
Use heat shrink at all ends to ensure no shorts.

Now Araldite the head and base together. Check the thing works before doing this as once its glued together, that's it!

Alternate idea(and maybe my next version!)
Dont get rid of the switch, wire this in and run a lead out of a new hole in the side wall.

Battery

---

I'm using 3xAA NiHM (3.6v) to run mine – nice and bright!!!. Used it for a few hours without it going bang!. According to Cree, the LED will take 3.6v happily. I know fully charged 3x NiMH are more than 3.6v, but I assume under load they drop and things should then be OK??

I've soldered 3 batteries together (to get a triangular shape) and then sealed them in an inner-tube housing. With a short wire with a DC plug on it, it sits beneath the stem quite happily. Check the web for soldering batteries – dead simple. To charge them in-line, you'll need a charger that can do this. Alternately, Maplin do a 3xAA holder that you can take the batteries out of to charge.




Have fun!



more at

http://s450.photobucket.com/albums/qq222/mark65_album/

Northwind

Did a bit of lateral thinking today and discovered that these work pretty well:

http://www.dogcamsport.co.uk/head-camera-mounts.htm



They're designed for bullet cameras, which are smaller, but the tesco aa torch still fits. I have to say it doesn't feel massively secure, which in some ways is good, if I fall off it's going to come loose on impact. I don't think it'll fall off, but I'm not 100% confident in it. Thing is, once you start spending money on this the £10 torch starts to make less sense! But I had it lying around anyway, and it's an easy fix for the less imaginative/practical.

forgotrafe

marks65 Nice bit of DIY and a nice write up. If you have two units and wired them in series you could run them off a radio controlled car racing pack which are 7.2v and come in sizes up to 4000mAh so would last hours.

FSR_XC

forgotrafe wrote:

marks65 Nice bit of DIY and a nice write up. If you have two units and wired them in series you could run them off a radio controlled car racing pack which are 7.2v and come in sizes up to 4000mAh so would last hours.

I was considering using something like this, but won't it be over volted?

Also shouldn't running x2 sets of 2500mAh AA in parallel last longer?



Should have some pics to post soon. I have a work in progress.

In the mean time anyone got any ideas on a waterproof case / cover for battery carriers?

FSR_XC

This is where I'm up to:

The lights:



On the helmet:



The battery carrier:


The back of the light unit has a solid ruubber bung, tight enough to make it waterproof (as is the wire hole).
Mount is from my Hope LED 1 helmet mount. Using 2 relector clamps to hold the heads.
This makes a lightweight light unit.

The plan is to use x2 battery carriers, attached to the back of the helmet with a velcro strap.

Just the switch and waterproofing of the battery pack to go. . . .

forgotrafe

FSR_XC wrote:

I was considering using something like this, but won't it be over volted

I don't know! Depends what voltage regulation is on the Cree chip!

FSR_XC wrote:

Also shouldn't running x2 sets of 2500mAh AA in parallel last longer

Yes, but I'm not sure there would be any real advantage in either solution.

Nice work so far with the dual lamp setup though!

FSR_XC

I have a added a switch and the battery carriers are in a poly bag so I can test it properly tomorrow night.

I am hoping to get a couple of hours use from 2x2 2300mAh AA's.

One light has the collumator removed, so I can get some spread of light. Testing in the garden it seems to work pretty well.

Compared to my Hope LED 1, the brightness is somewhere between setting 2&3 on the Hope and spread is a little wider.

The real test however is out on the trail.

BoardinBob

Numpty alert

Can someone clarift exactly where you should solder the wires for the external battery pack?

One on the spring on the LED unit (cutting the spring back, but where should the other wire be attached to? And is it the +ve or -ve that should attach to the spring?

Off to buy 3 x AA external battery packs at lunchtime.

fury21

FSR_XC wrote:

In the mean time anyone got any ideas on a waterproof case / cover for battery carriers?

Cheapest way I know of is a plastic vitamins/tablets tub or bottle with a 'mouth' wide enough for the battery pack. Punch a small hole in the lid for the wires to pass through and mount the whole thing upside down, so the lid (and wiring hole) are at the bottom. Simply unscrew the lid when you need to change batteries.

May not be to everyone's tastes though

BoardinBob

In the mean time anyone got any ideas on a waterproof case / cover for battery carriers

I'm planning on using a Specialized saddle bag. It'll be mounted under the stem and should be fairly waterproof. I've certainly never had any water ingress in all the time it's been mounted under the saddle.

FSR_XC

BoardinBob wrote:

Numpty alert

Can someone clarift exactly where you should solder the wires for the external battery pack?

One on the spring on the LED unit (cutting the spring back, but where should the other wire be attached to? And is it the +ve or -ve that should attach to the spring?

Off to buy 3 x AA external battery packs at lunchtime.

Centre is positive - spring / outer is negative

Mikey joe

Boardin Bob

I found it a pain in the arse to wsolder to the spring so I cut it off and sodlered to the outer silver disc which is also negative. the inner silver bit inside the green ring is positive

hope this helps

BoardinBob

Cheers guys

FSR_XC

FSR_XC wrote:

I am hoping to get a couple of hours use from 2x2 2300mAh AA's.
The real test however is out on the trail.

Actually managed 3 hours and they were still working, but not at the same strength.

Anonymous

how much have these set ups cost and how do they compare to other setups available?

FSR_XC

sheepsteeth wrote:

how much have these set ups cost and how do they compare to other setups available?

As I mentioned previously. A 2 light setup (as pictured) is similar to setting 3 (of 4) on my Hope LED 1.

I would guess that would make it around 180-200 lumen, but I would not use them as a bar light as the beam spread is not good enough. It is good as a head torch though (one unit with collumator removed).

My setup has currently cost:
x2 torches - £20
x2 battery carriers - £1.38
x2 connectors (for carriers) - £1.38
some wire
Switch - £1.50
Mount - bits from reflectors already had.

Total - £24.26

BoardinBob

Did the cut and shut job on two of my torches. First one took about 3 hours but the second one was done in about half an hour once I knew what I was doing.

I removed the switch from the end cap and removed the plunger. I drilled a hole for the wires at the point where the little wrist cord would loop through the end piece. It's relatively thin here so the drilling is minimal and drilling at an angle gives the wire an easy route ouit.

After I'd soldered the wires to the LED I ran the wire through the tailpiece and out the hole I drilled. I then epoxied the head to the tail piece and I took the plunger, reversed it and epoxied it into the hole where it sat when the switch was in place.

I couldn't see any inline switched in maplin so i just connected the wires from the LED to a snap connector for the 3AA battery box which means I have to attach it to the battery box to switch it on but it's no big deal.

The battery boxes are housed in a small saddle bag which is attached to my steerer and top tube with velcro straps.

The light output from the 3AA battery pack is far superior to the light when using two internal batteries. A quick test with the multimeter last night showed I'm getting 4.2 volts when the batteries are fully charged.

I've got a 3rd one to do and I'll take some step by step photos for anyone that's interested in seeing the exact process. I've never done anything like this before and it was great fun!

Mikey joe

Is there a danger you could burn the LED if using three AA batteries. 2xAA alkalines will give you 3V, 2xAA rechargeables will give you 2.4V. What can you run a 3W LED on without overvolting and burning it?