Mars 900w conversion


He just wants the Ganja!
Aug 12, 2016
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whats up my LED pros!

Looking for some advice here for my first DIY Project. I have a mars 900 that I'm wanting to convert over to a COB panel and I want to get it done in time for the Mephisto grow off.

I've opened up the panel and found 7 drivers that are labeled for 50-100w and 700Ma. I want to keep it simple for the first time and from what I'm reading I want to do two COBs per driver wired in series. I'm looking at the citizen clu48-1212 80cri x14.
Would this be a good cost effective choice for my first build? Is there a preferred vendor for the chips? Also would I want to reuse the three heatsinks already in the panel? Or are there better options that will easily fit inside the mars case?
Looking for any input. Thanks!!
That sounds good to start. Post some pics of the heat sinks so we can tell what they can manage. Also, the 1212s were on sale on, they might be gone now, supplies were dwindling when I got mine. I'd go for the 90 cri tho

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Multiply the wall wattage of the panel by .2 Which is close to 70 par watts. Not including driver and fan losses.

Then multiply the new expected wall wattage by .5 This should be over 170 par watts.

I think you'll be surprised on what your actually putting in there vs what you had. The benefit in these conversions is primarily that it's a cheap upgrade. Typically more light, less wall wattage, less heat and inexpensive.

You are also limited to the frame which is not a good thing either. That's why I always recommend keeping the par wattage close to the original in the panel. 14-25watt cobs in that little box is way to much light. If you wanted to buy 14 cobs I would never ever recommend doing it this way. Build a frame and install the cobs more spread out. Use 5 or 6 of the mars drivers as well as they will blow out and leave you stranded with missing cobs.

I did a few dozen conversions in the past and mainly for fun. If you run the cobs at lower wattage like these drivers push you do not need much as far as heatsinks go. I actually have a light I built on 1/8th inch aluminum without a heatsink at all and with fans in the room it hovers around 110-130 degrees.

Sell the light and buy 2drivers or keep the light and build it with 8 cobs is what I would consider.
Rep man

So when you are multiplying the wall wattage by .2 and then the new wall wattage by .5 that shows the difference in effeciency for the light correct?

In the case of using 7-8 COBs on the panel would I then still use all of the drivers with 1 COB/ driver? Or just remove half the drivers from the panel? This is also a panel wired with VEG and BLOOM switches so o could potentially run a few at 3000k and then a few at 4000k if I wanted to. I want to get the most effeciency out of the upgrade as possible but I'm not gonna have time to build out an entire frame right now. Maybe later on down the road I'll get further into it, but right now I'm really short on time.

Thanks for the good advice gentlemen.
Also my growing space is a 3x3

Here are a few pictures of the light.






You can see where a lot of the diodes are just burning up.
No problem, I'd run
4 cobs on one switch-2 drivers and the same for the other switch. So a total of 8 cobs and 4 drivers. Keep it all at 3500k and use the switches as the plants grow and mature. In early veg just use 4 cobs and later in use all 8.

Epi leds are in the 20% range for efficiency and cobs are 50+% efficient. There are also driver losses as well and a meanwell has just about the highest efficiency.
I'd do this configuration

The center 4 you could do on the bloom switch
The outer 4 could be on the veg switch. This would be the best bet for spacing and layout. Center 4 cobs would be to hot for the plants early on.

That looks like a good way to orient them. I just made my order on COBkits. Unfortunately they are out of 3500k so I grabbed 8 of the 3000k and the rest of the stuff needed for the conversion. I'll get another update posted when the materials get here and I start the process.

Thanks @BigSm0 ! You the man
Ok guys, here's an update on the conversion. Got my stuff in the mail yesterday and spent some time tonight working on the mounting plate.

Cut out my aluminum plate for mounting the COBs


Clamped and match drilled

Cleaned up all the holes and edges with the dremel


I decided to try out the precut thermal pads. If these don't work well I have some of the arctic silver paste to replace it with

Wiped down everything with alcohol and mounted the chips.

Well that's all for today! Hopefully tmmrw I will have time to wire them all up and test her out.