DIY LED light unit

Just finished the new light unit and am really happy with the result. Here are some pics:






Now with the problems
The LEDs are brighter towards the side where it conects with the PSU and are running hotter. The PSU I got exceeds the LEDs requirements, it has 6 Amps, while both LED strips require ~1.5 Amps each. Would this be of any concern and can the PSU damage the LEDs? It can be seen from the above pic that on the far side the LEDs are brighter.
The pelxiglass is 1-2 mm longer than the intended space and sits on top of the tank instead of falling into the groove. Apart from filing it, what other method can I use to shorten it as I'm afraid of damaging the wood or the silicone?

Hi m4r10,

hopefully addressing some of your questions and concerns, not necessarily in the order you raised them

There is no risk of the PSU damaging the LEDs based on it being over-rated for the LED strips unless it has a higher voltage than that required by the LED strips. The 6A output is the max rated for the PSU, however given that the LED strips will only draw 3A in normal operation, then the PSU will never run at full load.
The advantage this gives you is that the PSU will never run excessively hot. The voltage is constant from the PSU and the current drawn from it depends on the impedance of the load you connect to it, so you are safe in that regard

With respect to the LEDs appearing brighter closer to the PSU, this may well be the case and often occurs with Strip LEDs. The problem is due to them being in long strips, the further from the PSU, the less power available to drive the remaining LEDs. The only way around this is to determine if the strips can be split into shorter strips, if the specification detail for the LED strips states that it can be done, or if it stated that the LEDs have individual drivers (resistors), then you can make lots of short strips and split the PSU feed to the strips. You will not overload the PSU in doing tis as the total current demand is still only 3A but the power is more evenly distributed across all the LEDs. Hope this makes sense
Given that you have sealed the LEDs behind the acrylic sheet, I am not sure if you want to go to the trouble of opening it up again to try this.

Finally on the acrylic being 1 or 2mm too long, you could use a router to trim it a bit. If you use a router with a round over bit, then you can run around the sheet using the wood edge as a guide and it will leave you with a nice bevelled edge which will sit into the top of the tank no problem. If you are going to try this, you need the router at high speed and go slowly around the sheet of acrylic to minimise the risk of chipping it. Alternatively, you could use a sheet of sandpaper on a solid block to achieve the same result. Start with a relatively course paper like 120Grit and progress down to perhaps 600grit to achieve the final smooth finish.

Cheers,

Bill.

Thanks Bill for the advice.

You're right in saying I'm not in the mood of opening the unit again to make another connection on the other end. I could've done that before sealing it as I have a 2 way connector for it, but rushed to finish it. I guess the difference in the brightness it's more obvious as I connected 2 strips, so there's 10m in total. With the first opportunity, I will split it in 2.

About the cutting, I don't have a router, so the sandpaper route is the only option I have. It will be messier but have no choice.

You have open a whole new box of ideas for me......... Thanks m4r10 and well done on the lights.

Very interesting topic... Where did you get the components for this project

The LEDs and PSU off ebay.

Howdy!

The reason the strips at the end of the chain look dimmer is because the cumulative resistance of the strips and connectors is too great.
3A is usually too much current for the individual wires in the first strips to handle.
Normally, the (reputable) manafacturers of these strips recomend that no more than 4 strips (i.e. 4-5m length) are daisy chained.
What you need to do (soon!!) is to remove the linkage at every 4th strip (or 2nd!!) and start the wiring for the next 2/4 strips directly from the PSU again.
Otherwise, the heating at the start end you are experiencing (the main conductor wires getting hot) will lead to molten plastic, dead fish (plastic fumes BAD!!!), possible vapourised copper (dead inverts) and a fire.
Hope this helps.

Hi Murph. Cheers for the "reassurance"! Just found out that the PSU is underrated for the total length I have, so another one will be on the way soon and have no choice but open the unit again.
Regarding splitting the strip in shorter ones, will they run cooler as they draw enough current to satisfy their needs? If this is the case, will a 4 split cable be in order to use as it will be connected to the same PSU?

Hi,
What I meant was the little U linkages at the end of the strips you have, in the first picture. Only link 4 of your strips like this. Then start the next 4 with a new connection from the PSU, etc. Theoretically, they should run cooler like this (they certainly won't be a fire hazzard!).
It should be easy enough to adapt the left-over links to join to the psu (cut and screw!).
If your current PSU is under-rated, get a second (or third) one and allow more control options.

Another PSU is on the way and a split cable. I'll see how it goes when split in half, if still hot then I'll break them even more every 2 strips, just to be on the safe side. Thanks again for the input.