Parallel wiring, voltage drop, wire length etc

So I'm wiring up a new Samsung F-strip frame - this will be my fifth one of similar design - and I've always cut my wires the same length to equalise voltage drop. But this time I'm building for a friend and I want to keep everything neat and tidy.

Looking at these Samsung strips - which are 16S x 9P - I'm thinking: why do I even bother trimming my wires the same length (and rerouting them) when in fact the parallel circuits on the strips are already unequal lengths?

That is to say, on a 560mm strip, there is a greater distance for the current to travel from one end of the strip to the other compared to the 200mm18awg wires (the red and white ones below) I'm using.

Considering the voltage drop difference is less than 0.05% between a 100mm and 200mm 18awg solid wire - or 0.024v - surely it shouldn't make any difference? I'm using 48v CV drivers.



The new frame looks like the one above, but with 5 strips instead of 4 running on a 240w driver.

You answered your own question.

I guess I have. Obviously it works, I just wanted reassurance it's not a candidate for thermal runaway - even though the constant voltage driver should take care of that.

When I first started building theses, everyone said "make sure all your wires are the same length" . . . but after building a few, and thinking about it, I figured the small amount of variation in length shouldn't make much difference at all.

However, if anyone DOES see a potential issue with the way I've wired this board, I'd like to hear it sooner than later

Thermal runway is only a problem if you are running them hard. Even then it is caused by a breakdown in cooling.

The driver is probably fluctuating on voltage far more than the losses from the entire circuit, keep that in mind.

Cool. These strips are only going to be running at 40-50% in an air-conditioned environment. However, I've built extra capacity in case my mate wants to up the drivers (I've built two frames for him) from 240 to 320, which should max out around 85% (assuming the HLG-320H-48s will hit 370w as per the Mean Well test report). The 3mm alloy U-channels I've used seem to duct the heat nicely, especially spread out the way they are and with fans running in the room.

A few things I've learned on the way . . . the F strips are a lot easier to work with than the H strips (below), as the connectors are out of the way of the LEDs, they have aluminium backing (H series are fibreglass), and obviously you need fewer of them for the same wattage (though the H series have better light and heat distribution, and were a little bit – but not much – cheaper than the F series). Other than that, it seems to be a good, cheap and effective design.

Prawn Connery said:

assuming the HLG-320H-48s will hit 370w as per the Mean Well test report

Click to expand...

depends on the voltage of the load. look at max current on the test report instead of max wattage

Did do - 370w (assuming 48v).