Two obsevations:

1. The 672C is advertized as a 45W panel with continuous color temp change between 3200 and 5500 deg K. There are intermixed LEDs of warm and cold LEDs (color wise) in the panel, and a knob changes the relative energy between the two types to control the color. BUT you get the 45Watts only at about 4500 K - when both types are fully on. Going either way - to the colder or to the warmer end - will diminish the output of one type, and near the extremes you will get just about half of the overall light intensity. So if you want light output commensurate with 45W at 5500 K, the 672C will not give it to you - only the 672W (or the 672S)

2. The thermal design is OK, but keep in mind that due to the specific passive cooling design the panel must be positioned at close to vertical (upright) position as possible to benefit from the natural convection through the opening slots in the plastic body. I tested the 672C lying horizontally on a table (LEDs facing up toward the ceiling) in a room at ambient 23-24 deg C, and after 25 minutes of continuous full power the thermal cutoff got engaged, cycling 1/8 of the LEDS on one side on and off on a 20 seconds cycle. Rotating the panel to vertical stopped the power cycling.

I only have one problem with these lights. If I leave the batteries attached to the body they get completely discharged after one day. That happens even if the switch is set to off (0). Did anyone have the same issue?

I have used these lights quite a bit over the past year and half. I can confirm the two major issues with these lights - that they have thermal issues - usually when horizontal (think hair light) or with softbox when vertical, and that the batteries will discharge on the light when not plugged in when in the off position. I talked to Ted (the US rep) for the company a few months back at Photo+ and he acknowledged the overheating issue. He suggested removing the slide in diffusion panel to help with cooling. If I remove this, I can successfully use the lights on full power for hours without heating issues, even with the softboxes. So it's been a rather minor issue for me, and I just only use the slide in diffusion if the lights are not at full power or being used for a long duration. The battery discharging issue hasn't really been an issue for me, as the fact that you can charge the batteries in the light with included AC power supply is a huge plus for me. The price, compact size, and quality of light are really hard to beat in this range. Yes, they could be built out of metal, have a yoke, yadda yadda... but being able to get 3 of these in a case, with batteries, power supplies, reversible studs and umbrella adapters (basically a hinge for the light) plus 2 remotes for around $700 is a pretty sweet. I am able to fit 2 smaller LEDs (312 and 190) in the case as well, making for an uber portable battery/AC 5 point light kit. Mix in some Kupo or Mathews inverted compact light stands and you're good to go under $1000.

Softboxes

How does HR672S mix with TRI-8S and LS 1S? Willl I get tint issues, so the other light looks purplish and other greenish?

Thanks. It seems that TRI-8S and LS 1S are practically identical. HR672S is little different but looks very similar. I don't know from the chart that would I see the difference of HR672S and other two in practice.

Ah and I took the chart from HR672c, not S. Have you tested HR672S?

@kob wrote

"The 672C is advertized as a 45W panel with continuous color temp change between 3200 and 5500 deg K. There are intermixed LEDs of warm and cold LEDs (color wise) in the panel, and a knob changes the relative energy between the two types to control the color. BUT you get the 45Watts only at about 4500 K - when both types are fully on. Going either way - to the colder or to the warmer end - will diminish the output of one type, and near the extremes you will get just about half of the overall light intensity. So if you want light output commensurate with 45W at 5500 K, the 672C will not give it to you - only the 672W (or the 672S)"

Are you sure about this? The stated lux difference at 1 meter is 2080 lux (W) vs 1920 lux (C) giving a rather small difference.

Its clear that only half the LEDS will be used when usind at the coldest color temp setting, but this seems to be compensated by driving the remaining LEDs harder?