240W LED Grow Bar Teardown: inside a quality fixture
We stripped a bar-style Samsung LM301H grow light to its driver, LEDs, PCB and heat sink. Here's exactly what separates a good fixture from a cheap one.
Annotated component diagram
The diagram below maps the four main sub-assemblies of a bar-style LED fixture. Each numbered callout corresponds to a section in the spec table and component analysis below.
Component analysis
Samsung LM301H — 3500K + 660nm
2.80 µmol/J at 65mA drive current. The 3500K phosphor-converted white provides a balanced full spectrum; the 660nm deep-red supplements phytochrome activity. Far-red (730nm) emitters accelerate flowering response.
Meanwell HLG-240H-C2100B
Constant-current, 2100mA output, 100–277VAC input. IP65-rated, 0–10V dimmable to 10% output. 93.5% measured efficiency. 7-year MTBF. The B-suffix variant supports both 0–10V and resistance dimming protocols.
Extruded Al heat sink + 5W/mK thermal pad
6063 aluminium extrusion, anodised black. Fin pitch 8mm; measured junction-to-ambient thermal resistance: 0.18°C/W. 1mm silicone thermal interface pad between PCB and extrusion. No thermal paste (correct — pad prevents pump-out over thermal cycles).
Full component spec table
| Component | Specification | Verified |
|---|---|---|
| LED chipsPrimary emitter | Samsung LM301H, 3500K + 660nm red + 730nm far-red | ✓ Confirmed |
| Photon efficacy (PPE)Measured at wall | 2.75 µmol/J (spec: 2.80 µmol/J) | ✓ Within 2% |
| True power drawPlug-in monitor | 238W (spec: 240W) | ✓ Within 1% |
| DriverModel confirmed | Meanwell HLG-240H-C2100B, 93.5% efficiency | ✓ Confirmed |
| Input voltageUniversal | 100–277 VAC, 50/60 Hz | ✓ Confirmed |
| PCBAl-core | 1.6mm aluminium-core PCB (MCPCB), 1 oz copper | ✓ Confirmed |
| Thermal padInterface material | Silicone, 1mm thickness, 5 W/mK thermal conductivity | ✓ Confirmed |
| Heat sinkMaterial & finish | Extruded Al 6063, anodised black, 8mm fin pitch | ✓ Confirmed |
| DimmingProtocol | 0–10V analogue, resistance dimming; range 10–100% | ✓ Confirmed |
| IP ratingDriver enclosure | IP65 (driver); IP40 (LED bar) | ✓ Confirmed |
| DimensionsL × W × H | 1150 × 115 × 70 mm | ✓ Measured |
| Weight | 4.2 kg (driver included) | ✓ Measured |
| Warranty | 5 years LED (Samsung L70), 3 years driver (Meanwell) | ✓ Confirmed |
How we did the teardown
People also ask
What makes a grow light driver good or bad?
The driver regulates current to the LEDs. A quality driver (Meanwell HLG series, Inventronics) maintains constant current across input voltage fluctuations, operates efficiently (90%+), and handles thermal stress without drifting. Cheap no-name drivers run hot, drift in current (over-driving LEDs), and typically fail within 12–18 months. The driver is the most common failure point in grow lights — and the hardest to replace.
How do I know if my grow light uses genuine Samsung chips?
Samsung LM301H chips have a distinctive rectangular package with a phosphor dot visible under a loupe. Each chip has a Samsung identification marking. Counterfeit chips often have blurry or absent markings, inconsistent phosphor coverage, and lower binning tolerances (visible as uneven colour between chips when lit). The surest check is to compare the fixture's measured PPE against the chip datasheet figure at the stated drive current.
Does LED grow light efficacy degrade over time?
Yes. L70 is the standard measure — the hours before a chip's output drops to 70% of initial. Samsung LM301H is rated L70 at 54,000 hours at 65mA and 25°C junction temperature. In real installations, elevated junction temperature (above 25°C) accelerates lumen depreciation; every 10°C rise roughly halves the L70 figure. Good thermal management is the primary lever for maintaining efficacy over a fixture's commercial life.
The fixture we tore down is the one we sell
Same Samsung chips, same Meanwell driver. We put our name on it because we run it on our own shelves — and the teardown proves it's what we say it is.