What's the difference between the "LRS" and the "HLG" models? Seems the LRS's are cheaper than the HLG series?
Any 72v drivers?
The difference is that the LRS are much cheaper, but the HLG are dimmable and slightly more efficient.
Why would you need 72v drivers? I am guessing that you are thinking for some reason that three qb120s at 24v each need a 72v driver? Or two qb132s at 36 volts each equals 72v? That's not how it works. When wiring in parallel, for the qb120s, you need a driver with the model number ending in 24, and for the qb132s, which are 36v, you need a driver ending in 36. You don't add the voltages together for multiple boards unless you are using constant current drivers, which I will explain in a minute.
The qb120s are rated at around 60 watts each. So, for one board you would need the hlg-60h-24a. The "60" is the wattage. Two boards would need the hlg-120h-24a, the "120" is the wattage. Three boards (180 watts) would need the HLG-185H-24A, or you could get away with the LRS-200-36 because 200 watts is not much higher that 180. Four boards would need the hlg-240h-24a.
The "a" means that driver has a dimming pot installed. If there is a "b" instead, that means there are extra wires on it for you to install your own dimming pot. The reason someone might want the b version, is so they could install their own dimming pot on long wires to make it more convenient to dim the lights from a distance. With the a version, you have to have the driver in your hand to dim it, so that might be inconvenient to get to.
The qb132s are 36v and rated at 75 watts. So, one board would need the hlg-75h-36a, or lrs-75-36. Two boards would need the lrs-150-36 or hlg-150h-36a. It doesn't have to be perfect. For four qb132s at 75 watts each, that adds up to 300 watts. But, since it's cheaper, I use the lrs-350-36 because they don't make a 300 watt version.
I do know that some people run four qb120s with the LRS-350-24, even though four qb120s add up to only 240 watts, but I think that runs them a little too hot. A better fit for that driver would be to run five or six qb120s. Five qb120s at 60 watts each equals 300 watts, six would add up to 360 watts, so the 350 watt driver would be a good match.
These are all examples of drivers that you would wire in parallel, or constant voltage drivers. Note that with constant voltage drivers, the model number has the number of volts at the end, like LRS-350-24. The voltage of the driver must match the voltage of the board.
With constant current drivers, you would wire in series instead of parallel. With constant current drivers, the amperage is at the end of the model number, not the volts, such as HLG-240H-C2100A (the "C" means "constant current"). You would try to match the amperage with the amperage of the board. And with constant current drivers, they don't have a fixed voltage, they have a fixed amperage, not voltage. Instead, they have a voltage RANGE that the total number of volts of the boards added up must fall into.
For example, the qb132 is 36 volts and are rated at 2000 amps. So, if I want to wire 4 of them in series to a constant current driver, I would look at the HLG-320H-C2100A because 2100 is close to the qb132's rated 2000 amps. The voltage range on the data sheet for that driver is 76v-162v. Four qb132s at 36v each adds up to 144v, which falls within 76v-162v, so that would work. Note that three qb132s (108v total) would also work, but 320 watts would be a little too much for three boards because they are rated at 75 watts each for a total of 225 watts. Four boards, though, at 75 watts each would be 300 watts, so it is a good fit because that is closer to 320 watts.
It is ok to push these boards over their rated wattage. Ledgardener did a torture test with the qb288 which is rated at 135 watts. He pushed 600 watts into it and it was running fine...hot, but fine. When he got around 700 watts it burned up. So, these boards can take 4 times their rated wattage without burning up. It's just that the hotter you run them, the less efficient they are.
The qb120s are rated at 2800 amps. It is hard to find a matching driver for 2800 amps. The hlg series doesn't go that high in amperage until the 320 watt model (HLG-320H-C2800A) and at 60 watts each, you would need five qb120s to get in that wattage range.
If you wanted to power two of them at 120 watts, the HLG-120H-C1400 is as high as the 120 watt driver goes at 1400 amps. So if you ran two boards with it, you would not be getting max power use out of them. That is why I like to wire in parallel with constant voltage drivers instead. It is much easier to find a good match. Plus the affordable LRS series drivers are only constant voltage.
