Mars Hydro FC-E4800 Review

The New Mars Hydro FC-E4800 may be the perfect 4’ x 4’ grow light. It is exceptionally efficient, generates more than enough light, and the design allows for the best possible distribution of light. I think they made a lot of smart choices in designing the FC-E series fixtures. I appreciate the high diode count, the adjustable bars, the way the diodes are distributed along the bars, and the simple elegance of the build. The Mars Hydro FC-E4800 is an innovative high-quality fixture, and micromole per micromole, it costs about 50% less than most competitors.

I tested the larger Mars Hydro FC-E6500 when it came out in Spring 2021 (Test Report) (Video). It was among the highest efficiency fixtures that I have tested. The FC-E6500 is perfect for 5’ x 5’ grow spaces. The smaller FC-E4800 is ideal in a 4’ x 4’ space.

The FC-E series fixtures are an incredible deal. At only about $457, the Mars-Hydro FC-E4800 has a cost efficiency of only $0.42/ µmol. That is one of the very best prices for any light on the market. For the best deals, shop Mars-Hydro.com and use code: CCFC.

The Mars Hydro FC-E series are the first bar array fixtures that I have seen with adjustable bar positions. This is a feature that I often wished other grow lights had. Many fixtures are made with even bar spacing, which creates a hot spot in the middle. The adjustable bars on the FC-E series allow you to reposition the bars anywhere along the frame. They suggest two bar arrangements with arrows along the frame pieces. Both suggested arrangements move bars away from the middle and towards the ends.

Along each bar Mars-Hydro also moves diodes away from the center and toward the ends. At each end of the bars, the diode concentration is very dense, toward the middle of each bar there are relatively fewer diodes. This diode distribution along each bar coupled with the ability to adjust the bars allows the Mars- Hydro FC-E4800 to produce a very even spread of light across a 4’ x 4’ canopy.

I really like the elegance of the design and how the fixture comes together. It consists of two sleek, light-weight aluminum frame pieces and six LED bars. It is possible to mount the driver on the LED bars. They provide a driver mount with adjustable width to accommodate the fact that you may reposition the bars. However, they also provide plenty of cable, which allows you to locate the driver elsewhere. Assembly is required, but it is pretty simple. Watch the video review to see the complete assembly process.

The design of the FC-E series fixtures is simple and efficient. Being able to reposition the bars is great. The disassembled fixture can also fit in a much smaller box which saves considerably on shipping. I have tested several LED bar arrays that fold and several that disassemble. I firmly believe that disassembly is a superior solution.

The components that Mars Hydro incorporates into the FC-E series fixtures also help keep the price low. The Mars Hydro SP and FC series use Samsung diodes, but the FC-E series use diodes by Bridgelux. Many growers may not be familiar with Bridgelux; however, it is a USA based company. Test reports show that the Bridgelux diodes are comparable to the Samsung diodes. I questioned whether they would perform as well in my tests, until I tested the FC-E6500. Using Bridgelux diodes, the FC-E6500 recorded the highest efficiency of any production model grow light that I have tested!

One reason that Mars Hydro is able to achieve such a high efficiency is the number of diodes used. The FC-E series fixtures use almost twice as many diodes as most of the competition. The FC-E4800 has a total of 2646 diodes. The power draw is listed at 480 watts, which means there are over 5.5 diodes per watt. I usually consider 3 diodes per watt to be a good number. Some grow lights use fewer than 2 diodes per watt. The 5.5 diodes per watt on the FC-E4800 is really exceptional.

They include diodes with 5 different spectra. The full spectrum diodes are a mix of 3000k and 5000k. They also include UVA diodes near 410nm, red diodes at 660nm and far-red diodes around 730nm.

The FC-E series fixtures feature drivers by Moso. This is the third fixture that I have tested with a Moso driver, and they all performed well. Along with the Bridgelux diodes, the Moso driver saves cost without sacrificing performance.

The performance of the FC-E4800 is quite impressive. I ran it through three different PAR tests with two different bar positions. It is very efficient and produces an excellent quantity of light for a 4’ x 4’ grow. The innovative design with diode distribution and adjustable bars allows it to distribute the light very well across the canopy.

First, I set up the FC-E4800 with the bars aligned along the arrows on the frame (Position 1) and ran our official test. In our official tests, the Maximum PPFD is always 1000 µmol/m². The Mars Hydro FCE-4800 delivered a maximum of 1000 µmol/m² at a hanging height of 32.5cm (13in). The hot spot was considerably off center because of the way that the diodes are distributed.

The PAR map was so good with the fixture in Position 1 that I really had to think about what I could change in subsequent tests. There is a huge area in the center of the map in the maximum production range of 700 to 1000 µmol/m². The edges and sides of the map are also in the prime photosynthetic range with most PPFD values in the 600-700 µmol/m² range. The corners are the only place where the PPFD is below the 500 µmol/m² threshold.

In the official test, the average PPFD was 751.2 µmol/m², which is excellent. The Usable PPF was 1081.8 µmol, which is more than enough for a 4’ x 4’ space. The power draw during the test was only 471 watts. That means the Usable Photon Efficiency is an impressive 2.3 µmol/w. These are all excellent numbers that rival the most expensive high-performance lights on the market.

After analyzing the map from the official test, I felt the alternative position that Mars Hydro recommends is too radical. The distribution in position 1 is nearly perfect. However, I decided to make my own slight adjustments. In Position 1 the spacing between bars is 12cm, 19cm, 18cm, 19cm, 12cm. I adjusted the bars so that the spacings were 10cm, 20cm, 20cm, 20cm, 10cm. I adjusted the bars while the fixture was hanging in position after the Position 1 test, and I was careful to make no other changes.

I ran a second test with the fixture in the modified position. The changes that I made moved the bars very slightly towards the edges. Two of the bars were moved by 2cm and two were move by 1cm. This should help produce an even more even PAR map, but there is a tradeoff. When we put the sources of light closer to the reflective walls more of the photons will reflect off the wall rather than hit the canopy directly. It improves the distribution of light, but somewhat less light will reach the canopy. The changes that I made to the fixture were minor, but we can observe a slight improvement in the PAR map and a slight reduction in the Usable PPF.

In the Modified position, the corner PPFD values are all higher than in the Position 1 test. The perimeter values overall are improved with higher values along the top and bottom and similar values along the two sides. In the middle of the map the values are slightly lower. However, the amount of area above 900 µmol/m² does not change. The maximum PPFD went down to 980 µmol/m² and the minimum PPFD went up from 433 to 443 µmol/m².

The changes to the distribution are minor but I think they are an improvement. However, I also predicted a lower Usable PPF. In the Modified position, the average PPFD fell very slightly to 749.1 µmol/m². Therefore, the Usable PPF also ticked down to 1078.7 µmol. The power draw remained the same at 471 watts. So, in the Modified position, the FC-E4800 had a Usable Photon Efficiency of 2.29 µmol/w. If we continued to move the bars closer to the walls this pattern would continue. I think the Position 1 arrangement is nearly perfect. The modified position that I tested may be slightly better, but I think going further would be counterproductive.

I decided to run a final test at a higher hanging height. Raising the fixture will produce the same effect: the distribution improves, but the Usable PPF goes down. If you place priority on an even distribution and want the corners to be above 500 µmol/m², then raising the fixture is the best option.

I set the fixture back in Position 1 and I raised it to 41cm (16in) above the sensor. At this height, the values around the perimeter are the best and all but one of the corners are above the 500 µmol/m² threshold. The two sides saw the biggest improvement, and the top and bottom of the map remained relatively unchanged. However, in the middle of the map the values are marginally lower. The maximum PPFD fell to 920 µmol/m², but the area of the map in the maximum production zone of 700-1000 µmol/m² is basically unchanged.

In the raised test, the average PPFD was 731.5 µmol/m², which is still well above our recommended level of 700 µmol/m². The Usable PPF was 1053.3 µmol, which shows that raising the fixture cost about 28 micromoles in reflective losses. The power draw ticked up to 472 watts during the test, so the Usable Photon Efficiency comes in at 2.23 µmol/w. These tests show that there is a comfortable growing range for the FC-E4800. I would run it between 13 and 16 inches above the canopy during flower.

I tested the dimmer with the fixture in Position 1 after the official PAR test. The dimmer is continuously adjustable with a knob. There are markings at 25, 50, and 75%. As you can see in the graphic above, the dimmer is pretty accurate with the PPFD percentage consistently just under the dimming percentage. However, I would expect most growers will run the FC-E4800 on full power through most of the grow.

Finally, the ambient temperature during the tests was between 25.4 and 26.0C (77.7 -78.8F). I measured a maximum temperature on the LED bars at 51.2C (124.2F). The driver was located outside of the test area and hit a maximum temperature of 50.9C (123.6F). These are all well within the expected range.

I really like the Mars Hydro FC-E series. I love the quantity of diodes and the way they are distributed along the bars. I also really like the ability to reposition the bars along the frame, but without a quantum sensor, I recommend sticking to the two set-ups that I tested.

I am impressed that they are able to make a fixture with so many cool innovations and offer it for such a low price. 42 cents per micromole is so cheap that I double checked my math and then highlighted it in my notes. If you need to light a 4’ x 4’ space, I think the Mars Hydro FC-E4800 is possibly the perfect fixture. The FC-E6500 is an excellent option to light a 5’ x 5’ grow space. The smaller FC-E3000 should perform brilliantly in a 3’ x 3’ space. For the best prices remember to use discount code CCFC on the Mars-Hydro website.