Small build for succulents

[ukstripbuilder]

The 280mm Samsung L2 would require 4 Strips running Below ~ 800 mA @ 17.2 Watts max each, 50% of Max rated Amps (max rated 1.6 Amps) with minimal heat sinks...

I'm guessing you're assuming a linear I/V curve here? There doesn't seem to be an I/V plot in the datasheet for the L2 strips?

[PeteR_1]

The 280mm Samsung L2 would require 4 Strips running Below ~ 800 mA @ 17.2 Watts max each, 50% of Max rated Amps (max rated 1.6 Amps) with minimal heat sinks...

I'm guessing you're assuming a linear I/V curve here? There doesn't seem to be an I/V plot in the datasheet for the L2 strips?

No assumptions...
Actually tested the Vesta, BXEB Gen2 and several Samsung LED strips; F, H and V Series...

Samsung and Bridgelux LED Strips run below 50% maximum current require minimal to no heat sinking...
Bridgelux Vesta 2750G... viewtopic.php?f=32&t=5761
Samsung LT-F564B... viewtopic.php?f=32&t=5872

Four 280mm L2 Horticulture strips in a Vivarium... viewtopic.php?p=24466#p24466

[ukstripbuilder]

Four 280mm L2 Horticulture strips in a Vivarium... viewtopic.php?p=24466#p24466

Any idea how that "frame-like" layout affects uniformity (compared to just laying out the strips in rows)?

[PeteR_1]

Four 280mm L2 Horticulture strips in a Vivarium... viewtopic.php?p=24466#p24466

Any idea how that "frame-like" layout affects uniformity (compared to just laying out the strips in rows)?

No idea...
But can do a simple test with some 280mm Strips later this week and report back...

A three (3) strip 560mm (or ~ 6 strip 280mm) 5000K mock-up / test Build, parallel strip layout with measured uniform coverage... viewtopic.php?p=23538#p23538

[ukstripbuilder]

Having thought more about this, I've speced a 1ft Vestas build. Run soft, and with the supposed higher PPF/lm than CRI 80 (0.016 vs 0.014), the efficiency actually isn't too bad. I will run just the 5000K channel.

I'd run 2S6P as follows:

@23.75V / 254mW / 857lm / 142lm/W

Bridgelux Vesta 2750G Strips are;
560mm, 3272 Lm (@ ~ 0.016 PPF/Lm), 52.35 PPF, 24.8Vf, 1.0Amp, 25 Watts

142 Lm/W * 0.016 = 2.272 PPE
160 PPF / 2.272 PPE = 70.42 Watts

857 Lm * 0.016 PPF/Lm (cF) = ~13.71 PPF per Strip
160 PPF / ~ 13.71 PPF per Strip = 12 Total Strips

Driver load in 2S6P would be:
Voltage: 2 * 23.75V = 47.5V
Current: 6 * 254mA = 1524mA

Driver: HLG-120H-54AB

• Constant current range: 27 ~ 54V
• Current Adj. Range: 1.1-2.3A
• Efficiency at load: 70W/124.2W = 56% load = ~93% efficiency

Look reasonable @PeteR_1?

I'm still wondering if the Thrive (CRI 98) spectrum would be better as these are same cost (although single row/single CCT).

[PeteR_1]

@ukstripbuilder ,
The calculations look OK...

The max rated Amps for 280 mm Vesta Gen2 is 1.0 Amps (1000 mA), 50% of Max rated is 500 mA... Those strips can run at up to almost 500mA on the 5000K / a single channel (Or both total) @ ~ 2.2 PPE, before requiring heat sinks. The posted tests show ~ 2.5 PPE at 25% of Max rated Amps.

Can’t comment on the Gen3 Thrive, there’s no available info on % SPD, just the SQD Graphs. It may be possible that the 4000K Thrive could provide adequate and equivalent Blue wavelength percentage as the 5000K 80CRI LEDs, but it’s only speculation.

[ukstripbuilder]

@PeteR_1, another question regarding driver choice - Having read through most of @LEDG's guides, it seems he recommends running drivers in CV mode for strips wired in parallel, rather than CC mode as you've recommended. What's the logic behind your preference?

My understanding is that even for the same model of strip, ordered at the same time, strips can have slightly differing forward voltages (Vf). If these strips are wired in parallel, the current that flows through each individual strip will vary, regardless of whether driving with a CC or CV driver. How these currents vary differs for CC and CV modes as follows:

In CC mode:

• The total current provided to the strips in parallel is constant
• The current provided to each strip depends on all of the strips IV curves, where they must satisfy the relationship where, for the drive voltage, the currents derived from all the IV curves must sum to the total (constant) current. (This is probably explained better in section 1.1 of this document).
• Any potential thermal runaway occurring for a single strip, resulting in it failing open (no current passing) means that the total constant current now applies to less strips and could potentially cause a cascade across all the strips in parallel.

In CV mode:

• The voltage provided to the strips in parallel is constant
• The current provided to a strip only depends on the strip's own individual IV curve. The total current is the sum of each strips current derived from its IV curve at the fixed voltage.
• Any potential thermal runaway occuring for a single strip, resulting in it failing open (no current passing) means the total current reduces, but no other strip in parallel is affected.

If I am correct, I think the closer balancing of currents in CC mode is probably preferred, but the failure profile seems worse as a strip failure results in current increases to the remaining strips, potentially causing a cascading failure that cannot happen in CV mode.

Thoughts?

[PeteR_1]

@PeteR_1, another question regarding driver choice - Having read through most of @LEDG's guides, it seems he recommends running drivers in CV mode for strips wired in parallel, rather than CC mode as you've recommended. What's the logic behind your preference?

My understanding is that even for the same model of strip, ordered at the same time, strips can have slightly differing forward voltages (Vf). If these strips are wired in parallel, the current that flows through each individual strip will vary, regardless of whether driving with a CC or CV driver. How these currents vary differs for CC and CV modes as follows:

In CC mode:

• The total current provided to the strips in parallel is constant
• The current provided to each strip depends on all of the strips IV curves, where they must satisfy the relationship where, for the drive voltage, the currents derived from all the IV curves must sum to the total (constant) current. (This is probably explained better in section 1.1 of this document).
• Any potential thermal runaway occurring for a single strip, resulting in it failing open (no current passing) means that the total constant current now applies to less strips and could potentially cause a cascade across all the strips in parallel.

In CV mode:

• The voltage provided to the strips in parallel is constant
• The current provided to a strip only depends on the strip's own individual IV curve. The total current is the sum of each strips current derived from its IV curve at the fixed voltage.
• Any potential thermal runaway occuring for a single strip, resulting in it failing open (no current passing) means the total current reduces, but no other strip in parallel is affected.

If I am correct, I think the closer balancing of currents in CC mode is probably preferred, but the failure profile seems worse as a strip failure results in current increases to the remaining strips, potentially causing a cascading failure that cannot happen in CV mode.

Thoughts?

I thinks there is just some confusion in terminology.
The "Constant Current Range" of MeanWell LED Drivers refers to the Voltage range where 100% of max rated Current / Watts is available. My recommendation has always been Parallel wired < 60 Vdc SELV rated circuits which are usually CV Drivers, "Modes" are sometimes specific to the manufacturers. CC Drivers can be wired to Parallel circuits but the output is usually reduced well below the maximum rated Current / Watts.

LED Strips are not individual Diodes, strips consist of multiple Series and Parallel circuits, this reduces the chances of Thermal Runaway in any adequately designed fixture with heat tranfer and LED Driver with their "Limiting" Current / Watts. CC and CV LED Drivers are made for specific Maximum "Limited" Current / Watts Output which can be adjusted up or down with their optional internal or external manual adjustments. Properly Sized and Selected LED Drivers will eliminate the possibility of Thermal Runaway due to their “Limits”.

LED strips from the same manufactured batches are rated within specified ranges usually less than 1.0 Vdc. The small Possibility of Thermal Runaway increases when the strips are normally operated at their max rated Amps, a single failure may put them over the max rated Amps / Current. Operating Parallel wired LED strips “Softer” will not only eliminate this possibility, it will also increase their lifespan and Efficacy.

Properly selected Series wired LED Strips with CC Drivers eliminate the possibility of exceeding the “selected” maximum rated Amps, at the cost of High Voltage Circuits, but don't usually allow for much flexibility of adding or removing strips as with Parallel wired circuits with CV Drivers.

CC Drivers;

• Maintain a selected fixed Current e.g., 225, 450, 700, 1000, 1200, 1400 mA, etc.
• The voltage varies based on the sum total Vf (forward Volts) of all the connected Series wired Strips and can be high as 600 Vdc.
• Complete failure or disconnect of a single Strip will prevent all strips from operating, keeping the light Off.

CV Drivers;

• Maintain a selected fixed Voltage e.g., 12, 24, 36, 48, 56 Vdc, etc
• The current varies based on the sum total Amps (Watts) of all the connected Parallel wired Strips.
• Complete failure or disconnect of a single Strip will cause the current to flow equally to all other connected strips, only slightly increasing the current of each LED Strip, light will remain On.

[ukstripbuilder]

I thinks there is just some confusion in terminology.
The "Constant Current Range" of MeanWell LED Drivers refers to the Voltage range where 100% of max rated Current / Watts is available. My recommendation has always been Parallel wired < 60 Vdc SELV rated circuits which are usually CV Drivers, "Modes" are sometimes specific to the manufacturers. CC Drivers can be wired to Parallel circuits but the output is usually reduced well below the maximum rated Current / Watts.

Given my intended 2S6P wiring layout (at 47.5V/1.5A), am I right that this means I can't run any of the HLG-120H models in CV mode?

options.png (34.36 KiB) Viewed 2263 times

HLG-120H-48

• I can put the driver into CV mode by adjusting the Voltage pot down to 47.5V whilst leaving the current pot unadjusted (or lowered to just above the desired 1.5A).
• At 47.5 volts, I'm at the very top end of the 24-48V "full power" range with no room to increase / allow for unexpected inefficiencies

HLG-120H-56

• I can't put the driver into CV mode as the Voltage pot only adjusts as low as 49V and I want 47.5V
• The driver can be put into CC mode by setting the Current pot to 1.5A

Given you recommend CV over CC for strips in parallel, is there a more appropriate wiring arrangement / driver to achieve this? I thought about wiring solely in parallel (1S12P), but this doesn't help as the Vestas are so close to 24V you have the same problem, just with a lower voltage/higher current version of the HLG-120H.

[PeteR_1]

Given my intended 2S6P wiring layout (at 47.5V/1.5A), am I right that this means I can't run any of the HLG-120H models in CV mode?

options.png

HLG-120H-48

• I can put the driver into CV mode by adjusting the Voltage pot down to 47.5V whilst leaving the current pot unadjusted (or lowered to just above the desired 1.5A).
• At 47.5 volts, I'm at the very top end of the 24-48V "full power" range with no room to increase / allow for unexpected inefficiencies

HLG-120H-56

• I can't put the driver into CV mode as the Voltage pot only adjusts as low as 49V and I want 47.5V
• The driver can be put into CC mode by setting the Current pot to 1.5A

Given you recommend CV over CC for strips in parallel, is there a more appropriate wiring arrangement / driver to achieve this? I thought about wiring solely in parallel (1S12P), but this doesn't help as the Vestas are so close to 24V you have the same problem, just with a lower voltage/higher current version of the HLG-120H.

Those HLG-120H- series Drivers are CV “Mode” Drivers. They have fixed SELV voltage ranges for any Parallel or Series/Parallel Wired Circuits. The Voltage, Vf is still within the CC Region or Voltage Range of the LED Driver. For example you could make 4-Series / xx-Parallel Circuits with 12 Vdc LED strips, for 48 Vf.

• -48xx Driver has a 24 - 48 Vdc “CC Region", no adjustments needed
• -54xx Driver has a 27 - 54 Vdc “CC Region", no adjustments needed and is the best selection for your 2S/6P Circuit @ 47.5 Vf.

The HLG-120H-C series Drivers are CC “Mode” Drivers. They have fixed Current ranges with High Voltages for Series Wired Circuits. To power your 12 strips (in Series) needs a minimum (12 * 23.75 Vf) 285 Vdc LED Driver at the appropriate selected mA / Current.


The “Mode” terminology is confusing, it’s either;

• CV (Parallel or Series/Parallel wired) Driver or
• CC (Series wired) Driver.

The MeanWell CV + CC "Mode" Drivers are simply CV Drivers with internal circuitry that automatically adjusts the "CC (Voltage) Region" to output the maximum rated Watts, but it's still a CV Driver there is no actual "Mode" selection, just CV or CC Driver Selection.


BTW, Older technology CV LED Drivers' Outputs were relative to their Rated Current, for example a 120 Watt, 48 Vdc Driver with a 24 - 48 Vdc range, Rated 2.5 Amps produced;

• @ 24 Vdc * 2.5 Amps = 60 Watts max.
• @ 48 Vdc * 2.5 Amps = 120 Watts max.