Can this lantern be modded?

So I just purchased a really cheap lantern on the recommendation of my colleague and at MYR10.90 (about USD 2.8) it isn't really all that bad. Diffused light is way better than my generic cheap 3D cell lantern and it runs on 3xAA cells, which means I can run my eneloops in them (single eneloop costs more than the light though so might just use cheap alkaleaks hahaha)

This is the lantern, brand Tengjun model number TJ-F11


Opened up


The reflector (its just cheap coated plastic )


Anyway, opened it up and as expected it's screams cheapness. Basically it's just wires connecting the batteries to switch to...is that a driver board?, btw it measures at 35mm so was wondering whether anyone have any advise for some cheap mods to make this light better. Can I just replace that board with an LED star and solder the wires?



Although in terms of heatsinking it is practically non-existent though, so not sure if that might cause issues, anyway, I'd like it to be 50-60 lumens with the longest possible runtimes on 3xAA (nimh or alkaline)

If there is any link to a beginners guide somewhere about simple mods kindly let me know. Did read through the Beginners Guide To Modern LED Flashlights but didn't help in this particular application, or perhaps my understanding is inefficient.

Thanks everyone!

Board looks direct drive, perhaps a limit resistor only.

This is a mixed blessing. Plus side is you'll have long runtimes with tapering output... getting dimmer towards the end.

Going to a real driver would regulate you and give constant brightness.

Also, this:http://www.candlepowerforums.com/vb/showthread.php?394834-battery-efficiency-increased-runtime-mod
You could add a few switches and have different resistors in and out of the circuit for cheap, possibly scavenging the resistors and switches from some broken item.

great info, thanks more_vampires. I'm testing the runtime now with 3 x 1900 eneloop, so far still going strong at 6 hours 33 minutes, had to stop as was going to sleep (woken up by baby crying for milk though). Will continue the runtime test later at work. If it runs for 12 hours with usable brightness I guess I don't need to do anything to it.

Although the light is rather bluish so will have to tackle that problem first.

Doesn't look like a bad lantern at all, really. Looks like you've got lots of room to grow!

Gook luck, please post your mods if you try any. I love this stuff.

To get 60 lm out of a good modern LED should take less than 1/2W. If the LED is around 3.0V (which it would have to be to run off 3 NiMH cells), 1/2W takes 187 mA. If you round to 190 mA, that should theoretically give you 10 hours from 1900 mAh cells. A good low-dropout linear regulator should do the trick.

If the LED voltage is much higher, you'd need a buck-boost driver, which would considerably cut the efficiency.

Oh, and at that power level the star it's mounted on is enough heatsink, if there's some air around it.

Yeap, can't beat in terms of pricing haha.

So I found out something really interesting, I stopped the runtime test at exactly 7 hours, took out my eneloops and placed them in my C9000 to do a discharge to find out how much juice is left. Surprisingly, 20 seconds after i pop them in and select discharge modes the charger reports 'done' on all 3 batts, and all 3 registered at 0.9V.

Thing is, the lantern was still giving out really usable light when I stopped the runtime test, and they were doing this with practically depleted cells?....seems like a awesome vampiric lantern

I will try with regular alkalines when I have the time, probably with GP Ultra+ batts since they are cheaper in a 10 pack.

DIWdiver said:

To get 60 lm out of a good modern LED should take less than 1/2W. If the LED is around 3.0V (which it would have to be to run off 3 NiMH cells), 1/2W takes 187 mA. If you round to 190 mA, that should theoretically give you 10 hours from 1900 mAh cells. A good low-dropout linear regulator should do the trick.

If the LED voltage is much higher, you'd need a buck-boost driver, which would considerably cut the efficiency.

Oh, and at that power level the star it's mounted on is enough heatsink, if there's some air around it.

Click to expand...

Can you point me somewhere where I can procure these things?, fairly new at this stuff so I'm not sure of how to even search for the correct LED for this application.

When I first got this, I tried to measure current draw, I think I did it wrong, because it registered 4A and then I smell wire burning. Fortunately it wasn't fried haha.

I modified it before.
http://www.candlepowerforums.com/vb/showthread.php?391786

the 3.3V converter also drives a Neutral White 5050 LED [1S3P] very well.

Illum said:

I modified it before.
http://www.candlepowerforums.com/vb/showthread.php?391786

the 3.3V converter also drives a Neutral White 5050 LED [1S3P] very well.

Click to expand...

NICE!, thanks for the link to your thread, very detailed and informative....I guess this will be my small mod project now....and i can't believe over there they're selling it for 5 dollars

can I use this star?

http://www.fasttech.com/products/1609/10003889/1682002-cree-xm-l2-t4-7b-260lm-3000-3200k-led-emitter

10W / 2.8-3.7V / 700mA

Click to expand...

Direct drive? Yeah, but runtimes won't be so "hot." 3 cells in series would do it. You'll start having to worry about heat since it's a plastic host with no ventilation.

With driver? Yeah, depends on what you pick. Output could be almost anything.

So I had some more time to give this a lookover, initially abandoned the xm-l2 idea due to runtime and heat issues if direct driven like was mentioned.

I noticed that I have some SK68 clones lying around, I know from testing that the driver running those are 3 modes and the low mode pulls about 350ma...could I cannibalize the driver (soldering the wires directly to driver contact plates) from that and use it with my intended xm-l2 build? with the lantern?, of course it will be intended to be used as low mode only.

Tried finding a 1x7135 driver on fasttech but they were sold out :shakehead