Fixing this cheap but great headlamp

Other Types of Lights LED Headlamps
1

I need some help in fixing cheap-but-good headlamps.

Background
I live off-grid, and spend a lot of my time outside, even in the dark. I cook outside except when the rain is too heavy, and I don’t let darkness stop me.

LED headlamps have been the best tool ever for this, and they are amazingly cheap.

My first find was these Q5 headlamps, using 3XAAA batteries. They last a long time between charges, and despite being cheaply-made they are amazingly durable. At US$6.90 a piece, they are a fraction of the price of the grossly inferior lights available in the shops, and cheap enough to keep a stash of them to give them away as presents. The AAA batteries allow the use of alkalines, or nice safe NiMH rechargeables.

A few months ago I discovered some Cree XM-L headlamps for only about US$15. These are astonishingly bright. On their lower setting, they are like as bright as I could possibly want for cooking, and at full power they turn an unlit shed into daylight. The heads are fairly tough (survived lots of bumps), and the whole thing fits comfortably on my head. When they work, I couldn’t want better (tho a low-output mode would be a nice tweak).

The problem
The XM-L lights have a design flaw in the battery carrier. The contacts are not springs at either end, just thin metal folded downwards (which you can see it in the pictures on the advert, below).

So after several changes of my NiMH batteries, the folded metal contacts start to fatigue, and then break off, killing the light. Part of me says that this is to be expected with such cheap lights, but the rest of me says that there must be some way of fixing this one weakness in an otherwise excellent headlamp.

The best idea I have had so far is to break off all the folded metal contacts, and replace them at each end with springs. However, after breaking off the folded metal, the total clearance between battery ends and contact board is only about 6mm … and the smallest spring I have found so far are these 7mm diameter/10mm height springs from FastTech. Trying to squish a pair of 10mm springs (one at each end) down to 6mm seems to me to unworkable. :frowning:

So I’m not sure what to do. Buy the 7*10mm springs and cut them down? Find smaller springs from another source? (Where?)

Alternatively, any suggestions on where I could buy a separate 4XAA battery holder with built-in switch and driver?

2

Hi, Bean! Do you know for sure the driver is in the pack? It seems like it would be easier to replace the pack for one with springs, but you’ll need a switch too. FastTech also have a 4 AA pack with a little switch.

3

I have that headlight too and really like it. I have not used mine enough to wear out those battery contacts, but am interested in a "fix" too. I agree, it is the weak point of the light.

-Garry

4

Good point, I just presumed that the driver was in the pack, cos that’s where the switch is. But on second thought, that seems unilkely, cos there is no heatsinking in the plastic pack. If I can find my jewellers screwdrivers, I will try some dismantling.

However, I don’t think that your suggested battery packs will be viable. The pack part of a complex plastic moulding which includes the strap holders. Unless any new pack replicates those functions, I can’t see any way of attaching it.

5

Duct tape or rubber bands to hold the pack? Kind of just kidding :)….

What about if you used velcro straps, on the head band, and the some of those sticky backed velcro strips on the back of the new battery pack? If you also connectorized the pack-to-light connection, that’d also have the advantage that you could have several backup battery packs, or maybe even use a different pack maybe that takes a 18650 (assuming the voltage was matching)?

6

I saw the rubber(?) over case in the pictures but didn’t realise it had other roles. It is difficult to make out. I thought it would just clip on. Is it waterproof/splashproof too?

7

tale apart the pack, carefully saw out the portion that holds the batteries with a keyhole saw or serrated pocket knife, then jb-weld in a 1x18650 holder from DX, solder up the wires, throw in a fenix 2600mah protected 18650 and you should be laughing (good to go).

this method allows you to retain the “shell” of the original battery holder, but modifies it with a 18650 ‘upgrade’ module, retaining the original switch and functionality. I have done this many times on cheap headlamps and portable electronics (even modded my tv remote to use a 18650 to be more eco-friendly)

The Fenix 18650 is just an option, use any brand you like, I just happen to have a dozen or so Fenix cells on hand, and they have stood the test of time, hence why I recommend them.

8

http://dx.com/p/3-7v-1-x-18650-battery-holder-case-box-with-leads-100999 (Battery holder)

http://www.newegg.com/Product/Product.aspx?Item=9SIA1JX0NF2487 (Fenix 2600mah 18650)

9

Thanks for that suggestion. It’s an interesting idea, and I may give it a try with one of the headlamps to see how it goes. Just playing around with an 18650 against the existing batt holder, it looks like it will be a rather ugly repair, and I wonder how waterproof it will be. (I live in one of the most rainy parts of Ireland, which is a generally rainy country to start with).

However, I see that the same style of light unit is available with a twin 18650 batt holder, for only US$17.09. That seems like a battery option than a botched mod, so I’ll start by getting one of them and see how I like it.

10

Id try adding the spring to just the negative end of the holder. The spring should compress enough to allow the positive end to slide in. Having springs on just one end will provide pressure for the positive end as well. Just a thought, based on how decent battery holders tend to be configured.

11

You could also use some tiny magnets to fill the space if only using one spring, e.g.:
http://www.fasttech.com/products/0/10001047/1090500-rare-earth-neodymium-nib-disc-magnets-20-pack

12

for waterproofing, you could seal the seams around the battery holder with clear rtv silicone (automotive product so it should be easy to find). I’ve used it for years for quick0fix waterproofing. and I know what you mean. Here in louisiana it rains a lot too. good thing though, cause on a clear day the temps can get as high as 130 (F).in the sun.

13

Yes, that is how decent battery holders tend to be configured. (Rant: it amazes me that anyone would try to save a few pennies by making a battery holder any other way).

However, in this case the backing plate at each end is recessed behind plastic, so I will need 1mm or 2mm of something there to get a contact. Probably best to just use a blob of solder at the positive end, with the spring at the negative … but spaces will be tight.

14

If you do switch to 18650 check these out $11.66 for 2

http://www.fasttech.com/products/0/10001980/1141102-panasonic-ncr18650-rechargeable-2900mah-37v-18650-

15

One spring is the way to go. It should work out. Flatten the other contact slightly and reinforce the bend area with solder to make it more solid.