MarsHydro 300w COB conversion....kind of!

Discussion in 'Lighting' started by HotBunz, Apr 16, 2016.

  1. What I have is a year old MarsHydro 300w "old model" LED fixture. This is the "real" "old model" with the 180w output rating. Plugged into my Kill A Watt watt meter it is using 173w of power. At just a couple of months over being a year old she has lost a couple of diodes already. With information gathered here and other internet sources my plan was to just do a "standard" Cree COB conversion. But like many of my 'plans" things get turned around and expanded on as I dig into them. Now instead of using the Mars housing and just swapping out the diode panel for COBs I am going to use just the guts. I dug up an extra heat sink I had laying around from one of my salt water reef tank projects. It is 7"x 15.75". This version of the MarHydro 300w fixture uses 4 55v-100v .55-.6A drivers to power the diode panel. I will be using one of these drivers to power 2 Cree cxb3590 3000K 36v CB Bin COB's. I had a lapse in thinking and should have just bought a pair of 72v cxb3590s as they were the same price but the 36v versions will work fine for now. I am also using the 12v1A power supply to power either a 140mm fan or 2 of the factory Mars fans though they are a little loud. I was going to draw up in CAD a quick program to drill the COB mounting holes on the heat sink but as luck has it the desk top computer that runs my SolidWorks and Mach3 that powers my CNC milling machine has took a dump....this sucks because I was needing my milling machine to do a couple other things with the heat sink. I guess I will have to work around this and still get the job done. So this is the basic layout on the top side of the heat sink and a look at the inside of the stock MarsHydro 300w.

    Mars300oldmodel.jpg basiclayout.jpg
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  2. I was able to enjoy a day off from work today and spent my free time working on getting this light together and powered up. I must say it was just to easy to do. First I wanted to strip the black anodizing off the bottom of the heat sink. But I just didn't want to have to mix up a batch of my anodizing stripper(real nasty stuff) so I just broke out some medium grit wet sandpaper and went to work. I then layed out my COBs using Ideal COB holders, Ideal reflector adapter and the Ledil Angelina reflector. I drilled and tapped 2 holes for each COB held with 4-40 machine screws. I then sorted out where I wanted to mount the 140mm PC fan, the PC fan power supply and the LED driver. I had to drill a few other holes to mount them. I pulled out the power cord plug from the MarsHydro fixture and made an easy little mount so the power cord comes out the side of the new fixture and not out the top like on the MarsHydro unit. I never liked the top mounted cord on the factory unit. A little quick wire work and 5 minutes with the soldering iron and it was done. The COB holders are great as you don't have to do any soldering to connect the wires to them. I powered up the new fixture and confirmed everything was running as it should. I then connected it to my Kill A Watt watt meter and she is only using 42 watts of power! It is sitting here 5 feet from me running for the last 2 hours and I can't even hear the fan and there is almost ZERO heat coming from the unit. Frankly I doubt I even need the fan and will do a test run to see how if runs without the fan. I love this thing already. Now if my Mephisto Genetics seeds get here soon I can start my next grow.

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  3. thanks for doing this write up. I plan to do something similar in the future with some old mars guts.
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  4. Very cool man, I know one day my lights will break down and this is a cool idea.
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  5. Hey very kool write up. Question. What if one were "hell bent" and wanted to use the entire guts except the diode board? Would you be say able to run two 72v Cree versions only or would you have to step down to something like a Citizen 1212 because of the flimsy heatsink? Could i get away with four Citi 1212s?
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  6. Did you rewire the whole unit with 18AWG and solder those to the driver? My unit has 22AWG wire which is quite flimsy

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