Driving multiple XP-G2 triples?

Flashlight Modding and DIY Parts
1

Question. Say i wanted to use 3 or 4 of the triple XP-G2 on copper…These guys

http://www.mtnelectronics.com/opencart/index.php?route=product/product&product_id=83

I am not 100% clear on the series-parallel relationship when getting into series/parallel stars, and then the voltage requirement of triples.

Could you take say, a 9A SST-90 driver, set all the stars to parallel, and run all 9-12 emitters?

Can each star get 2.25A(4 triples) or 3A(3 triples) each, and each emitter getting 1/3 of that?

How would it be wired? Would it work?

2

Parallel - Voltage stays the same, Amperage increases.

Series - Voltage increases, Amperage stays the same.

3 in parallel @2.25A each would be, 6.75A just for the three.

If you wanted 9 in parallel @2.25A each, you would need a 20.25A driver.

I don't know of you could do series/parallel. Well, I guess you could. I would think it would be better to wire the leds on the stars in series and then wire the leads coming off the 3 stars parallel.

If you used 3.7V as the target per led, then series/parallel as described above would mean 11.1 Volts and 6.75 Amps.

I would need to make a drawing up and post it. It will take me a few minutes.

If you are going to do that, then I would spend the bucks and buy a good dependable driver like the taskled.

3

If it's all in parallel, the voltage requirement is the same as a single XP-G2 emitter and current will be divided by the number of emitters you have.

To wire it, think of it in two sets.

  • Wire the LEDs on each individual star in parallel using solder blobs.
  • Wire all positive ends of the stars together.
    The wire all the negative ends of the stars together.
  • If you read for ten minutes on basic electronics on nodal analysis, this means that all the positive poles of the LEDs are connected to a single node and all the negative poles connected to a separate single node.
Keep in mind that if a single LED shorts, all the LEDs will stop working (all the current will bypass the others through the short).

You would be able to run this config off a single battery (with VERY high current capabilities) through a buck driver, a lot of batteries in parallel config.
If you wire the boards in parallel with each other and the LEDs on each board in series, only one LED will fail if there's a short across it, but the increased voltage on the other two LEDs on that same board will increase the current significantly and will burn them out if not rectified in time.

Wiring the boards in series and the LEDs on each board in parallel, in the event of a single LED short, would cause that particular board to fail as the other LEDs on that same board would be bypassed.
4

p1

For Parallel LEDs on the star

s1

For series LEDs on the star

p3

For Parallel Stars

s3

For Series Stars

So you could use Parallel LEDs on the stars and then wire the stars to the driver in Series.

Or however you want. There are pros and cons for everything as ramblings discussed in the 2nd post.

5

So i would run each star in series, and wire all positive and all negative together to the positive and negative of the driver, effectively running the stars in parallel

And a parallel setup could use a high amp driver… correct?

I do not have an objection to buying a quality driver and programming via PC.

My idea is to run this off three batteries - And currently the carrier is setup to be in series so 12.6V.

Taskled drivers seem like the ticket, just not sure i have 35mm of space however.

6

This would be great for a King. SRK would hold three stars I believe. Change the four batteries to series. That would hold a taskled driver!

7

SRK will fit four with room to spare, just barely short of enough room to squeeze in a fifth one in the center.

8

So any standard driver will work with series stars in parallel?

Are you looking at the taskled hbflex?

9

A 3XP configured with LEDs in series requires the same voltage as multiple 3XPs configured with LEDs in series connected to the driver in parallel. Think of each board as a single 9v LED.

The voltage required will drop a bit with each series board you add in parallel, as the current will be divided among them, and lower current requires lower forward voltage, but it's not a huge difference. Check out Match's Vf graphs for a single LED, then extrapolate from that.

~3.1v for one at 1A, so 9.3v for three in series (a single 3XP unit). For three series 3XPs in parallel, you'd need 3A at 9.3v.

~3.3v for one at 3A, or 9.9v for a single series 3XP, and a driver capable of 9A at 9.9v.

These Vf numbers will fall as heat increases, but on copper boards it'll be fairly minimal.