Mini Maglite

[Ant]

i have just built a 7 led white flashlight using the deign based on Phantomas2002 mini maglite he used 3 N cells , i have 7 led in parallel and 3 AA 1600 mAh Nickel Metal Hydride batteries ,the voltage is 3.8v under load and the amps start at 200 but rise to 300 in less than a min , and the leds start to get warm , do i need to use a resistor or when i use (they are on order ) 3 2/3 AA 600 mAh will that not be such a problem


Ant

 

[vcal]

Ant-is the LED brightness diminishing, OR becoming more "bluish" after 1-2 min. of operation?-if so, you're probably overdoin' it...
BUT,-if that's the case, then how am I getting away with running 4>2/3AA Nimh batts. in my Lightwave 2000 (only 4 Nichia 5600s-in parallel), right?

p.s.-thanks again for that great link on the NimH batts!

 

[Ant]

the light looks ok ,,, maybe it is my test meter i will have to dig out my old one and check the results ...


i think that the first link that i have found before some one else has ,,, lol


Ant

 

[Go Go Gadget Flashlight]

If the current goes up over time, you're prolly heating up the LEDs. Shouldn't take much resistance to get it back to a good level.
I used a 0.3 ohm resistor in a bank of 20 parallel LEDs and that was perfect to keep them from thermal runaway. Got to make sure you're resistors can handle the current tho. Mine runs at 700 ma.

 

[**DONOTDELETE**]

Hi Ant!

I hope you didnt encounter too many problems with the plans...

I use either 2 Lithium AAs or 3 N cells in my Mini Mag. How do you get 3 NiCd AAs in? Do you use not a regular MiniMag but a 3AA light?

If there is a raise in current, I would strongly recommend a resistor to keep the current below 200 mA. My MiniMag runs on about 170 with 3 N cells and gets slightly warm, so I think 200 mA would be a reasonable level.
Measure the voltage at 200mA of the LEDs using a Lab Power supply and a resistor. Then subtract this voltage from the voltage of your 3 NiCd AA cells (about 3.6 V) and calculate the resistor.

I hope you have fun with your light!

Bye,

 

[Ant]

i did use a standard Mini mag , but did not have any 2/3 AA to use so i just wired 3 full sized AA together for testing , i am now have 3 2/3 AA 600 mAh rechargeable Nickel metal hydride batteries and form the testing tonight it looks if a resistors must be used, starts at 200mA 3.85V and a rises a little slower than before but still gets to 300mA in two mins , that's when i stop testing , also measured the temperature this time, it got to 30C (86F) .....
......... just done some testing with a variable resistor and a value of 0.4 Ohm gives me 180mAh steady if i go to 0.3 ohm it starts at 190mAh but starts to rise very slowly .

many thanks for the help

Ant

 

[**DONOTDELETE**]

Hi Ant!

I would risk it and try how high the current rises if you dont stop at 2 minutes. I would suggest to stop at 500 mA, but I think it wont come so far. I think you could live with a current of about 70 mA per LED, though this will reduce lifetime by far.

I still dont have an idea, where you could place a resistor in the minimag, I thought perhaps of a thin slice between two batteries.
I dont know how long your batteries are exactly, but could you fit a disk of about 1.5mm between two batteries?

Bye!

 

[Ant]

Hi Phantomas2002
i had to use a spacer in the mag light as the 3 2/3 AA bateries were not long enought the gap is 9mm so i have loads of room for a ressistor , or maybe some thing else.

i will have test to see if the the current does get to 500 mA

Ant