100W of Cree XM-L build thread. A slow start. - The Planted Tank Forum
Reply
 
LinkBack Thread Tools Display Modes
post #1 of 32 (permalink) Old 10-19-2011, 06:11 PM Thread Starter
Algae Grower
 
PTrader: (0/0%)
Join Date: Oct 2011
Location: UK
Posts: 87
100W of Cree XM-L build thread. A slow start.

My LED's arrived today.
So I thought it time to start this thread.

Aim: a stylish 100W light fitting to fit my 6'x2'x2'. It should replace and supercede either of my current T5 fittings (either the 4x35W or the 2x80W luminaire.)

Design: a watercooled aluminium bar with 10 x 10W Cree Xml LEDs suspended with a reflector.

The Cree's:


I'm now waiting on the driver and a few plumbing bits...

More to come soon.

create random acts of beauty...
silvawispa is offline  
Sponsored Links
Advertisement
 
post #2 of 32 (permalink) Old 10-19-2011, 08:53 PM
Planted Tank Enthusiast
 
h2oaggie's Avatar
 
PTrader: (22/100%)
Join Date: Feb 2011
Location: Cypress, TX
Posts: 688
Mmmm, water cooled, very intriguing! I assume you are running them at near max current (3 A)? I look forward to watching this build.
h2oaggie is offline  
post #3 of 32 (permalink) Old 10-19-2011, 09:55 PM Thread Starter
Algae Grower
 
PTrader: (0/0%)
Join Date: Oct 2011
Location: UK
Posts: 87
The cooling bar, cleaned up and sprayed gloss white. It deserves another couple of coats tomorrow I think, as it will be partly on show above the tank.

And yes, high power, the driver is apparently set for 2.8A.



Almost everything sourced and ordered except the folded aluminium sheet for the reflector, but I have 3 or 4 leads on that.

(Note to self, source hanging wires.)

create random acts of beauty...
silvawispa is offline  
 
post #4 of 32 (permalink) Old 10-19-2011, 11:09 PM
Wannabe Guru
 
PTrader: (0/0%)
Join Date: Aug 2010
Location: Wake Forest NC
Posts: 1,121
Is painting the tube a good idea where they will be mounted? Seems to me like it would interfere a little with thermal transfer.

Otherwise I'm looking forward to this!


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
redfishsc is offline  
post #5 of 32 (permalink) Old 10-19-2011, 11:51 PM Thread Starter
Algae Grower
 
PTrader: (0/0%)
Join Date: Oct 2011
Location: UK
Posts: 87
Hence the masking tape stuck to the bottom of the bar! It's clean bare alu under there

create random acts of beauty...
silvawispa is offline  
post #6 of 32 (permalink) Old 10-31-2011, 01:39 AM Thread Starter
Algae Grower
 
PTrader: (0/0%)
Join Date: Oct 2011
Location: UK
Posts: 87
The kids are of school for a week now, so progress has been slow.

The driver arrived, so it was time to mount the LED's and solder them.
All went reasonably smoothly. If slightly messily, especially since I've ended up having to use silicone sealant in the screw holes.We'll see how that idea holds water next week. Literally.



You can see the power socket ready to mount into the reflector unit.
All the wiring will be taped/glued down and hidden in the gap between the cooling bar and the reflector. (the bar will sit in the groove of this reflector.)



So heart in hands I throw the switch..

...and let there be light. and lots of it, but only briefly. Notice the bare 12W cfl for comparison.I ran it for a few seconds at first, then realised it was thermally OK, so...




It is ridiculously bright, and not as hot as feared. Without liquid in the pipe, chip temperatures stabilised at 48ļC, measured where the LED chip meets the star mount board, after 5 minutes the heatsink bar was getting warm too. So after a voltage reading across an LED (3.2V) I thought I needed to take a current reading.

This is probably where I made a stupid error. To measure the current I put the meter into the circuit in the same way as I have before, (but I haven't done it with an LED driver.)
The driver went bang and died. No obvious damage. What did I do wrong? (Apart from buying a cheap driver!)

So I have a slight setback, but nothing I can't get over.

Now waiting on a new driver, but at least I can get the plumbing sorted!

create random acts of beauty...
silvawispa is offline  
post #7 of 32 (permalink) Old 10-31-2011, 02:52 PM
Wannabe Guru
 
PTrader: (0/0%)
Join Date: Aug 2010
Location: Wake Forest NC
Posts: 1,121
Quote:
Originally Posted by silvawispa View Post
This is probably where I made a stupid error. To measure the current I put the meter into the circuit in the same way as I have before, (but I haven't done it with an LED driver.)
The driver went bang and died. No obvious damage. What did I do wrong? (Apart from buying a cheap driver!)

So I have a slight setback, but nothing I can't get over.

Now waiting on a new driver, but at least I can get the plumbing sorted!

Did you hook the multimeter inline with the LEDs such that current had to flow directly through it to get to the LEDs (or, after the LEDs, before it reached the driver...... same thing)?


It's also possible that you were already on the max voltage output for the driver, and the resistance added by the fairly thin wire of the multimeter just put the driver out too much.


Now if you had just touched the + and - terminals across the driver as you would for voltage, you would have shorted it out badly, and almost certainly caused a problem.


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
redfishsc is offline  
post #8 of 32 (permalink) Old 10-31-2011, 03:38 PM
Wannabe Guru
 
hbosman's Avatar
 
PTrader: (2/100%)
Join Date: Oct 2006
Location: Leesburg Virginia
Posts: 1,741
Yeah too easy to forget, current is measured in series.
hbosman is offline  
post #9 of 32 (permalink) Old 10-31-2011, 08:35 PM
Planted Tank Enthusiast
 
Naekuh's Avatar
 
PTrader: (1/100%)
Join Date: Oct 2011
Location: Los Angeles
Posts: 884
nice!

i love led projects! its what got me back into this hobby!



ive tried playing with a standard reflector and with the led's and noticed its not that great of a improvement.

the LED's arc isnt behind or 180 degree's sideways so the reflectors actually end up being usless on LED's.


Quote:
Originally Posted by silvawispa View Post
Design: a watercooled aluminium bar with 10 x 10W Cree Xml LEDs suspended with a reflector.
EDIT:

OH wait 10W CREEs? :O

And is u using the tank water as the coolant or you going to have the watercooling on another closed loop?

Watercooling is actually my forte... :P
Naekuh is offline  
post #10 of 32 (permalink) Old 11-01-2011, 06:32 PM Thread Starter
Algae Grower
 
PTrader: (0/0%)
Join Date: Oct 2011
Location: UK
Posts: 87
Quote:
Originally Posted by redfishsc View Post
Did you hook the multimeter inline with the LEDs such that current had to flow directly through it to get to the LEDs (or, after the LEDs, before it reached the driver...... same thing)?

Yes, exactly this, I know better than to short out a circuit to measure current. (But only because I had read the instructions on the multimeter, electronics isn't my strong suit.)

voltage across one led was 3.2v, i have since realised there can be a bit of variation in LEDs but even so the driver is rated for 36V so I should have had some headroom.

@Naekuh, The reflector isn't so much for improving lighting efficiency as for shielding the room from the harsh glare and looking really cool

I'm using tank water for cooling (or leds for tank heating, take your pick...)

Still no news on a new driver

I wish I had the knowledge to follow O2surplus's designs for homebuilt drivers. I think it'll take me another year or 2 before I get even half a handle on understanding those systems.

create random acts of beauty...
silvawispa is offline  
post #11 of 32 (permalink) Old 11-01-2011, 07:31 PM
Planted Tank Enthusiast
 
Naekuh's Avatar
 
PTrader: (1/100%)
Join Date: Oct 2011
Location: Los Angeles
Posts: 884
OK some things about using the tank water as the coolant...

i actually pondered on the idea however alu is a really bad material especially in fish tank.

Its just too risky to use because if you have a metal which is reactive, copper is one, the alu starts to literally melt, or possibly some impeller shafts could effect it galvanic-ally.
(the risk is too great with alu + electronics without the presence of a corrosion inhibitor.)

If you are going on this route, i would recommend u cool the alu bar via waterblocks attached to it... and the waterblocks you should use are these guys:

http://www.koolance.com/water-coolin...product_id=115

As they are entirely made of acrylic and plated gold.
And almost nothing reacts to gold.

Unless u intend to run a titanium pipe inside and try to get the pipe to abosrb the heat?
Naekuh is offline  
post #12 of 32 (permalink) Old 11-01-2011, 08:35 PM Thread Starter
Algae Grower
 
PTrader: (0/0%)
Join Date: Oct 2011
Location: UK
Posts: 87
Quote:
Originally Posted by Naekuh View Post
i actually pondered on the idea however alu is a really bad material especially in fish tank.
I thought about this too.

One thing is for sure, there is no other metal in my water. My impellers are all ceramic, and the wiring had better be waterproof! (also, any copper would kill my snail population, I had this once when a piece of hat wire was caught up in a plant bunch. It did a remarkable job of clearing some algae too. )

In fresh water galvanic effects are limited as the alu oxide layer is fairly stable. It becomes a real issue in salt water. (I've been sailing boats in fresh and salt water for nearly 30 years, I understand a little about the process.)

The DC current will have a very limited induction effect within the aluminium, so the electrical driving force for corrosion will be low, theoretically! If any current is escaping onto the cooling bar I'll track it down and stop it.

I'm still concerned about using bare alu though so I think I'll coat the inside of the bar with acrylic paint (I'll literally just fill it and pour it out) and have an extra barrier at the cost of a slight loss in the heat transfer. (it will also make it salt water safe if I ever need a reef light...)

P

create random acts of beauty...
silvawispa is offline  
post #13 of 32 (permalink) Old 11-01-2011, 08:40 PM
Planted Tank Enthusiast
 
Naekuh's Avatar
 
PTrader: (1/100%)
Join Date: Oct 2011
Location: Los Angeles
Posts: 884
i think u just putting a open gap in the centertop... then attached a cross blower to the hole, you could get a better cooling solution without having to use the aquarium water....

a cross blower is something like this:
http://www.overclockersonline.net/im...large/pc21.jpg

Cooler Master should make one also.

the pipe then would work like a wind tunnel, forcing cool air in the center... and then hot air would shoot off the sides.
Naekuh is offline  
post #14 of 32 (permalink) Old 11-02-2011, 02:04 AM Thread Starter
Algae Grower
 
PTrader: (0/0%)
Join Date: Oct 2011
Location: UK
Posts: 87
Naekuh, you're missing half the point, I want a more efficient tank set-up.

I already have water and pumps. I'm also wasting heat from my lights at the same time that I'm running a heater.

There's a really graceful solution and I'm following it. Your concerns on the alu have convinced me to coat the interior of the bar with a neutral substance, but the overall system design doesn't need expensive computer parts just yet!

P

create random acts of beauty...
silvawispa is offline  
post #15 of 32 (permalink) Old 11-02-2011, 05:25 AM
Planted Tank Enthusiast
 
Naekuh's Avatar
 
PTrader: (1/100%)
Join Date: Oct 2011
Location: Los Angeles
Posts: 884
Quote:
Originally Posted by silvawispa View Post
Naekuh, you're missing half the point, I want a more efficient tank set-up.

P
just helping ya think out of the box.. :P
Naekuh is offline  
Reply

Tags
None

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the The Planted Tank Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome