1 year later: Inside the Mars Hydro 300w (60x5w) LED light

It’s been just over a year since I started using the Mars Hydro 300 watt grow light. Taking a look inside it clearly needed a quick disassembly…

Mars Hydro 300W melted blue LED's

A few LED’s were visibly melted/burned. To be specific, 4 of the blue ones towards the center. I’m not sure if there’s something different about *those* particular 4 (compared to the other blues in this unit), but needless to say, these ones were toast. Before anyone asks, I did check to make sure there had been thermal paste behind them, and there was.

Mars Hydro 300W melted blue LED's - closeup
Mars Hydro 300W melted blue LED's - closeup #2

I ended up replacing them with a few cheap white LED’s that I had kicking around, along with some fresh thermal paste.


As to other internals, I found out where the fruitflies had started going once my fly tape was full:

Mars Hydro 300W - fried fruit flies, yum!

Air compressor took care of things there. I was tempted to replace the thermal paste behind the heatsink (5 screws to detach heatsink from PCB), but the existing thermal paste had it glued on pretty good so I decided to leave things be.


Looking at the fan and drivers…

Mars Hydro 300W - fan and drivers

This had stayed pretty clean and dust wasn’t an issue. I gave it a quick shot with compressed air afterwards since I had it open anyway.


With the new LED’s soldered in, I plugged it in and was up and running….

…except for 1 other white LED that I’d missed.

Mars Hydro 300W - blue led's replaced - 1 more to go!

I pulled it apart later and swapped out that final LED. All was now well!


Thoughts After 1 Year of Ownership

This grow light’s seen various degrees of usage over the last year. Periods of running 24/7, periods of sporadic use on a timer, and periods where it hasn’t been in use at all.

I’m a bit disappointed that 5 LEDs went.┬áIt’s generally been well ventilated (ambient temps of 18-24 degrees C), and I really wouldn’t have expected LEDs to start dying. If Mars Hydro cheaped out somewhere, I’d guess it was in the LED brand/quality.

I do really like the rest of the unit itself though. The fan is fairly quiet, I haven’t had a power supply (LED driver) die yet (despite losing a few other drivers in other systems), the thing has a heatsink against the PCB, bypass diodes are used to keep the good LEDs running when an LED dies, and some of the “little things” are there too (bushings to electrically isolate PCB from screws that go into unit, cables nicely zip tied, ample thermal paste used, easy disassembly, etc).


February 2019 Update

A number of years later here… half the LEDs in the unit stopped lighting up. My first thought was a dead driver. However, I swapped drivers around and it turned out both drivers were fine! I pulled out the bench power supply and found 5 of the white LEDs out. Replacing the LEDs had the unit up and running again.

As to why the LEDs being out stopped the whole string from working? Two guesses here:

  • It’s possible one of the zeners (bypass diodes) run in parallel with a dead LED also happened to die.
  • It’s possible the sheer number of dead LEDs pushed up the required voltage so high that it ended up out of the driver’s max output voltage (since the zeners are undoubtedly higher voltage than the white LEDs).

In any case, if half your LEDs go out on this panel, before assuming it’s the driver, swap the drivers to make sure you aren’t simply losing half the string due to a number of dead LEDs. For those who do need a driver (a couple have asked), I did come across eBay listings for 50W/60W 600mA 54-105V drivers which would likely work as a drop-in replacement around the $15USD mark. You may have to search around a bit as high-voltage drivers aren’t super common, but they do seem to be out there.