So it’s no surprise the meanwell hlg-185h-cxxxx is one of my favorite drivers. It’s the cheapest cost per watt out of the constant current line, and comes through with an impressive 94% efficiency rating when setup properly. Here is a screenshot of the data sheet page 1.

The Cree cxb3590 is one of the most popular cobs for horticulture. So I see fit to use it as our first example. Here is the chart showing it’s forward voltage at different currents.

Using the 36 volt nominal version, you can see that at 1400ma the forward voltage comes in just under 35 vdc. Using power calculation, (35v x 1.4a) you’ll come up with a 49 watt power consumption at that current. We’ll call it 50 watts. So if we want to run those cobs at 50 Watts with this driver, we’ll need the hlg-185h-c1400. If we find the column for that output current, it lists the dc output voltage range from 71-143vdc. In order to find how many 50 watt cxb’s we can run, simply divide the voltages by the forward voltage of the cob. For the minimum (71/35) you’ll see that the number is greater than 2. That means you’ll need a minimum of 3 cobs to meet the minimum voltage requirement of the driver. For the maximum, 143/35, you’ll see that number is just over 4. Since you can’t get a partial cob, that means the maximum amount of 50 watt cxb’s this driver will run is 4. If you’re looking to run less than 3 or more than 4 at that current, you’ll need a different model.

Now take the 1050ma model. Since it’s still a 200 watt driver, the lower output current means the voltage minimum and maximum will change. In order to get to the same amount of power with less current, we need more voltage right? The voltage range on the 1050ma model is 95-190vdc. Using same math you should come up with 3-5 cobs. So you gain a cob, yay right? Not so fast… going back to our power calculation you’ll see these are just a smidge under 40 Watts, like 37. No surprise, four 50 watt cobs or 5 close to 40 watt cobs both equal about 200 watts. There’s just a little more leftover voltage with that led and driver at 1050ma output.

Going down to the 700ma driver, the voltage range is like 143-286. So 5-8 25ish watt cobs.

There are a few things you need to keep in mind when looking at your different options. Most of the connectors that come built in or as part of the cob holders are rated for around 300 volts. Some are higher, but whatever they are you want to be careful not to exceed them. Also, a lot of the drivers will stay in constant current mode a s couple of volts higher than listed. But it’s definitely a crap shoot. All of the voltages listed on led data sheets are “typical” and if you read the fine print, they always give themselves a range. So if you’re calculating for typical (which is normal) and completely fill or go over your available voltage, and get a couple of higher than typical voltage cobs, I’ll have bad news…