flood light 1 xml or.2 parallel?

[nicko42004200]

With 1 xml t6 it pulls 3.3ish amps directly driven on a 18650. I added a second one, and my Amps through the switch are 3.0 amps. Are both getting 3.0 or is that split in half? I think they are both getting 1.50. How do I get them to 3 amps off 1 18650 or if I run 2 parallel 18650's will they pull full 3 amps? May wana go three xmls. But Gota figure out 2 first. Please help. Also battery gets warm off 2 but stay cool running 1 ???? Idk.

 

[Mattaus]

On 1 xml t6 pulls 3.3ish amps dd 18650. I added a second one and my Amos through the switch are 1.75. Are both getting 1.75 or is that split? I think there both.getting 1.75. How do I get them to 3 amps off 1 18650 or if I run 2 parallel 18650's will they pull full 3 amps? May wana go three xmls. But Gota figure out 2 first. Please help. Also battery gets warm off 2 but stay cool running 1 ???? Idk. Please help

Firstly I can tell you typed this up on a phone. Fixing your spelling, grammar and punctuation may help people understand what you're trying to do...

You've written "On 1 xml t6 pulls 3.3ish amps dd 18650". I'm assuming the 'dd' stands for direct drive, in which case I suggest you don't use direct drive and instead just purchase a cheap as chips driver to do the work for you. There are several drivers on DX or KD that will power 3 series connected XM-Ls but these typically need 12V input. The other option is to buy a TaskLED driver that does around 9A+ output and just wire them in parallel.

Anyway - fix your post and I'm sure you'll get better informed help 🙂

- Matt

 

[nicko42004200]

I am sorry. I am on a phone and it does mess up with auto correct even after I change things. But I redid my readings. On one 18650 bypassing switch I get 3.2 amps. I added a second battery in parallel and my amperage went up to 4.5 amperage draw. Now this number is split between the two led's correct? If i change to 2 18650's in serial and change led's to serial also. Would this give me the 3.2 amp draw to both led's. I thought I read somewhere that in series the amps are cut in half because of the higher voltage. So would it draw say 1.6 amps off of 8.4 volts but be running at around 3 amps output???? And I do apologize for my bad grammar . I am not the greatest at proper English.

 

[Mattaus]

I am sorry. I am on a phone and it does mess up with auto correct even after I change things. But I redid my readings. On one 18650 bypassing switch I get 3.2 amps. I added a second battery in parallel and my amperage went up to 4.5 amperage draw. Now this number is split between the two led's correct? If i change to 2 18650's in serial and change led's to serial also. Would this give me the 3.2 amp draw to both led's. I thought I read somewhere that in series the amps are cut in half because of the higher voltage. So would it draw say 1.6 amps off of 8.4 volts but be running at around 3 amps output???? And I do apologize for my bad grammar . I am not the greatest at proper English.

That's alright man - just helps us help you 🙂

In series you voltage will double but current will stay the same, in parallel voltage will stay the same but your current will double. Same principle for providing power and using power.

2 series connected 18650 batteries will give you 8.4V (freshly charged, 7.4V nominal) but only supply roughly 3A (note this current depends ENTIRELY on what type of 18650s you use).

2 parallel connected 18650 batteries will provide only 4.2V (3.7V nominal) but theoretically could supply double the current (6A).

Whatever you do you must match your LEDs to your batteries. So if your batteries are series connected then your LEDs should be as well. If you connect parallel XMLs to an 8.4V battery system they will break.

Parallel batteries means parallel LEDs. You can connect parallel batteries to series LEDs, but the voltage likely won't light the LED up, but at least they wills till work with the proper voltage.

I still don't think it's a good idea to be direct driving XMLs with 18650s because 4.2/3.7V is well above their standard operating voltage and you will probably damage them or at least significantly shorten their life.

 

[nicko42004200]

But there is the resistance in the switch,writing,and battery box. On fresh charged 18650. I do get 3.35 fv and it.pulls 3.4-3.5 amps. I use smaller wire at the led to slow the current down. But what about my amp reading? Is that number divided by the number of led's I have paralleled? So my 1 battery, say 3amp pull, is it 1.5 amps to each led????? That is what I'm trying to figure out.

 

[Gunner12]

You can test the resistance of the switch, turn the switch on and measure the resistance across it with the DMM.

If you are using thinner wires to try to reduce the current, then the wires can also get hot since they will be acting as resistors (depending on how thin the wires are)

Parallel meas you split the current and series means they get the same current. So 4.5A across 2 LEDs in parallel means the LEDs get 2.25A each assuming they have matching Vf.

 

[AnAppleSnail]

LEDs that see less current are more efficient. LEDs at lower current will run at a lower voltage. So if you use 2 LEDs in place of 1, they run in parallel at a lower voltage, which means a battery can deliver more current. You might imagine a battery as an infinite-capacity source of current at some voltage (1.5v, 3.7v, etc), and not be too far off for small loads. In reality, the battery has "Internal resistance" which accounts for its delivered voltage dropping at higher current. This also helps calculate how much the battery will heat up. An imaginary battery of 1 ohm internal resistance (Very high!) delivering 3A will drop its voltage by (V=IR) 3v. This means that a lithium-ion cell with 1 ohm internal resistance would only deliver 0.6v!

It's hard on batteries to run them hard. Sipping power lets them last longer, and is more efficient, and running hard has few benefits. I'll bet you an internet dollar most people can't see the difference in output between a 3 Amp and a 2 Amp XM-L dropin without a side-by-side comparison...and any difference quickly goes away as the 3A dropin heats up faster and dims because of hot LED. The 3A one will have much worse runtime, though.

 

[bigchelis]

6~9A off a single IMR 18650 will not give you the best results since they do sag under load.

Just cause IMR 18650 cells can take 9~10A doesnt mean they perform best at that current.

At 5A you should be good and seeing great OTF lumens with those Cells.

bigC

 

[nicko42004200]

I'm thinking about adding a third t6, and running 3 separate circuits with 3 switches. So I can turn them on individually. Have one no reflector,one a 10 deg., and the last a 45-90, 3 batteries . I do have green imr cells I got out of a laptop. So they are money. I have the room so I think it will be a great every needed task light. Flood, beam, and in-between. All on separate switches. The no lens like they are now flood my house awesome. I killed all the lights it was pitch black , kicked it on and I could see the hole house confront of me and even down the halls directly beside me. I think its awesome. i will post some pics when I get it all done. I was just curious about the amps being split between multiple immeters. Thanks ya'll!!!

 

[alpg88]

i build camping light, with 2 xml u2, wired parallel, running from 1 8xamc7135 driver, each sees 1,4 amps. they run cooler, more efficient than 1 driven at 2,8A.
don't see nothing wrong with running 2 parallel dd from 1 li ion cell, did that before, as long as current isn't higher than 6A from the start, there is no need really to use driver. i tried my light in dd before, 2 parralel xml do not pull more than 5a in dd even from imr26650, i also tried 18650, and 32650.
if you add third in parallel, even better, less load on each, more efficient, and runs cooler. i added driver to mine so i could run it from almost any battery, up to 36v, but if i was running it on 18650 only, i would not bother with driver, leds are running in safe voltage\current range.

 

[nicko42004200]

Exactly my thought 😉

 

[hellokitty[hk]]

Hi.
I would put the batteries in series then use a 8xAMC7135 driver with the LEDs in series.
You will have to arrange the circuit so that the first LED is connected to the batteries before the driver so that it will drop the voltage of the 2s batteries by ~3.3. Then goes your driver, and the next LED, all in series.
Circuit would look like this Vbatt -> LED -> AMC7135 -> LED

For 3 batteries and 3 XM-Ls, I would take the same approach but of course you'd have to put 2 LEDs in front of the driver to drop the voltage, and one behind the driver. Again all in series.
Vbatt -> LED -> LED -> AMC7135 -> LED

This will ensure even current distribution even with different vf of the LEDs, which may lead to uneven power distribution if you simply parallel the LEDs.

 

[alpg88]

this is what i build in few days from stuff i had available. didn't care for looks.
2xml parallel, 1 8xamc7135 heatsinked both sided, and voltage regulator, also heatsinked,
i didn't even use the regulator, , i don't need it with 6v lantern battery (big one with screw terminals), ran 2 nights it pbly did dim closer to the end, but there was always enough light over 12ft table and around it as well. the driver's radiators didn't even get warm, but when tested from 12v car batt, for few hours, radiators from both driver and voltage regulators were hot.

no optic, frosted polycarbonate, the round holes are about 1 1\2in

http://i876.photobucket.com/albums/ab324/alpg88/1111.jpg

 

[alpg88]

in the back, type m power jacks from radioshack.
http://i876.photobucket.com/albums/ab324/alpg88/2222.jpg

putting leds in parallel, was bad idea with cheap 5mm leds of inconsistent quality, cree xml, and cree in general, are way ahead of those quality\consistency wise, so no worries there, plus you don't go over the speck for single led, with 1 18650, even if one led fails, the other one can handle all current. did it before never had problems.