how does dimming work in relation to efficiency and drive current?

Lets assume over 4sq ft:

Setup A:
(4) cxb3590 36v 3500k CD on (1) HLG-185h-c1400B dimmed to 50%

Setup B:
(4) cxb3590 36v 3500k CD on (1) HLG-80h-c700B at 100% power



1. These setups pull approx the same wattage amount from the wall, correct?


2. Is Setup A just as efficient as Setup B? Same PPFD? Same heat emitted? Same Par W? obviously setup A has the potential to run a higher PPFD if run at more than 50%.



Also, what is the difference between a 0-10V dimmer and a pot? When running either of these on Setup A, are you altering the drive current with the dimmer? Or just lowering the wattage?

If the dimmer doesn't alter the forward voltage and therefore Setup B would be more efficient up to a certain point, would it be wise to configure a setup with these 4 cobs, and mount BOTH drivers on the fixture, and with the quick switch of some wires be able to run a higher efficiency during veg and early flower, and then change the driver for upping the ppfd into the 1000+ range?

Setup A well be very similar to setup B when dimmed down but allows you to run at higher currents if desired. There may be a small efficiency penalty for not maxing out the driver but it won't be much. No need for two drivers.

The forward voltage changes as the current changes. Check the data sheet pr the Cree PCT for the actual numbers.

Setup A will perform less efficiently than setup B. Reasons. Setup B is designed to be 64% efficient, while setup A is designed to be 56% eficnet. Dimming setup A does not change the amount of current or amps, you draw, just discards half of them through the potentiometer, 100k, that is its job to waste current at a given resistance.

Setup B is more efficient and will perform more efficiently drawing the same amps for the duration of its existence, as 2was designed, while setup A will discard half of all of its amps decreasing the efficiency to maybe 28% through heat losses, called resistance. if you have to keep your fixture dimmed to 50% change the driver to the lower rated driver and be happier, and watch your power bill go down too. it is not watts we are seeking, it is lumens at the most efficient rate we are seeking. New ballgame, new rules. peace.

BTW, I run 4 CXA3590 5000k, 72v, with a HLG-185H-C700B, very efficient and bright too.

The dimmer is a 0-10 v device, reducing volts from 10v to 0v. You must place a 1000 ohm resistor on the positive side to keep the CoB from goping to zero,a s i was told that is a no-no. A 1000 ohm resistor and a 10k dimmer switch/pot are what is needed with a B model mean well. you can get both at mouser.com or other reliable vendors on the internet, where you purchase your CoB's most likely. peace. You are not changing the AC side of the driver you are effecting the DC side of he driver with a dimmer switch, reducing voltage to the LED's not reducing voltage draw from the wall outlet, that requires less amps to reduce voltage draw. V=I/R, Volts = Current/Resistance. The C1400 draws twice as many amps and half as many volts made available. peace

In theory....Can a dimmer make a light be like, say, 80% efficient if it's dimmed down really low?

tstick said:

In theory....Can a dimmer make a light be like, say, 80% efficient if it's dimmed down really low?

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dimming has the oppposite effect of what you are thinking. it creates inefficiencies through heat loss. peace

what you want to do, is control the amount of current draw to be the lowest, and the lumens to be the highest. that is lighting efficiency. peace

VegasWinner said:

Setup A will perform less efficiently than setup B. Reasons. Setup B is designed to be 64% efficient, while setup A is designed to be 56% eficnet. Dimming setup A does not change the amount of current or amps, you draw, just discards half of them through the potentiometer, 100k, that is its job to waste current at a given resistance.

Setup B is more efficient and will perform more efficiently drawing the same amps for the duration of its existence, as 2was designed, while setup A will discard half of all of its amps decreasing the efficiency to maybe 28% through heat losses, called resistance. if you have to keep your fixture dimmed to 50% change the driver to the lower rated driver and be happier, and watch your power bill go down too. it is not watts we are seeking, it is lumens at the most efficient rate we are seeking. New ballgame, new rules. peace.

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Are you sure the potentiometer wastes off energy? Are you talking about putting the potentiometer on the dimming wires or the led leads?

I ask because when I dim my B model meanwell the Kill-a-watt shows it pulling less watts from the wall. This contradicts what you are saying

watts are not volts. less watts means less amps, not less volts. Voltage remains constant based on load, plus additional loads, resistance of wires and devices. use a voltmeter to measure volts and amps, but do it in parallel, and if you do not know what you are doing, do not do it, you can hurt yourself measuring in parallel. The drivers being used are constant current, amps, whatever you start with, it dra2ws that same level of amps no matter what, dimming just reduces the volts to the CoB's is all. The Cob's start out at or around 12 volts and the dimmer reduces it to near zero volts,not near zero amps. it is amps that kill not volts. a C700A/B uses 0.700 Amps while a C1400A/B uses 1.400 Amps, twice as many amps at the same volts 110v. peace

VegasWinner said:

watts are not volts. less watts means less amps, not less volts. Voltage remains constant based on load, plus additional loads, resistance of wires and devices. use a voltmeter to measure volts and amps, but do it in parallel, and if you do not know what you are doing, do not do it, you can hurt yourself measuring in parallel. The drivers being used are constant current, amps, whatever you start with, it dra2ws that same level of amps no matter what, dimming just reduces the volts to the CoB's is all. The Cob's start out at or around 12 volts and the dimmer reduces it to near zero volts,not near zero amps. it is amps that kill not volts. a C700A/B uses 0.700 Amps while a C1400A/B uses 1.400 Amps, twice as many amps at the same volts 110v. peace

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you clearly have absolutely no idea how drivers actually work and i fear for the safety of anyone who takes anything you've said in this thread seriously. you're not just wrong, you're dangerously wrong.

VegasWinner said:

dimming has the oppposite effect of what you are thinking. it creates inefficiencies through heat loss. peace

Click to expand...

Sorry man, but you are quite incorrect.

OK Just to clarify which efficiency I am speaking of...

SETUP X: @ 56.3%
(4) CXB3590 3500K CD 36V @ 1.4A (49W ea) on (1) HLG-185H-C1400B
4*49 = 196 dissipation W *.563 = 85.7W heat///// 110.3 Par w
110.3 total Par W / 4ft² = 27.575 Par W / SQ FT = ~1236 PPFD

SETUP Z @64%
(4) CXB3590 3500K CD @ 700mA (23W ea) on (1) HLG-80H-C700 (lets just pretend it can run all 4 at full 23w for this, i know supra's chart says only 3.9)
4*23 = 92 dissipation W *.64 =33.12W heat ///// 58.88Par W
58.88 total Par W / 4ft² = 14.75 Par W/ Sq FT = ~660 PPFD


SO my question is if I took Setup X and I used either a 0-10V dimmer or a pot (i still dont understand the difference) in order to lower the dissipation W from the wall down to match the dissipation W of Setup Z (92w) , is it still running at 56.3% efficient? or is it now seeing 64% efficiency?



So the difference would be like this:


Setup X dimmed down to ~47% of Max ( .47 * 49w = 23.03w ea)

@56.3% = 4x23 = 92 dissipation W *.563 = 40.204w Heat.///// 51.796 Par W
51.796 par w / 4ft² = 12.95 ParW/sqFt = ~ 580 PPFD

As a general statement and I say general because dimming characteristics are dictated by the drivers capacity to dim and its relationship with a particular dimmer and that can vary from driver to driver. Efficiency can degrade but is often offset by the reduced current increasing led efficacy and it can alter harmonics and power factor, I would say its intuitive that driver performance across a dimming range is never likely to be consistent
Cheers
Mark

VegasWinner said:

watts are not volts. less watts means less amps, not less volts. Voltage remains constant based on load, plus additional loads, resistance of wires and devices. use a voltmeter to measure volts and amps, but do it in parallel, and if you do not know what you are doing, do not do it, you can hurt yourself measuring in parallel. The drivers being used are constant current, amps, whatever you start with, it dra2ws that same level of amps no matter what, dimming just reduces the volts to the CoB's is all. The Cob's start out at or around 12 volts and the dimmer reduces it to near zero volts,not near zero amps. it is amps that kill not volts. a C700A/B uses 0.700 Amps while a C1400A/B uses 1.400 Amps, twice as many amps at the same volts 110v. peace

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I understand what watts are (volts x amps) and how to measure them.
Constant current drivers with dimming adjust the current (amps) while allowing the voltage to "float". The cobs start out around 34 volts and will increase in voltage as the current goes up. Please edit or delete your "advice" so someone doesn't get hurt or destroy their equipment

How extreme can you go with the "dimming" by connecting additional leds to the same driver?

Example 42v 1.5amp driver can drive 1 CXA3070 or as I am currently testing 2 in parallel, when does the bottom drop out and the driver will no longer power the led's. I have not seen a forward current limit or lower voltage limit for that matter.

VegasWinner said:

Setup A will perform less efficiently than setup B. Reasons. Setup B is designed to be 64% efficient, while setup A is designed to be 56% eficnet. Dimming setup A does not change the amount of current or amps, you draw, just discards half of them through the potentiometer, 100k, that is its job to waste current at a given resistance.

Setup B is more efficient and will perform more efficiently drawing the same amps for the duration of its existence, as 2was designed, while setup A will discard half of all of its amps decreasing the efficiency to maybe 28% through heat losses, called resistance. if you have to keep your fixture dimmed to 50% change the driver to the lower rated driver and be happier, and watch your power bill go down too. it is not watts we are seeking, it is lumens at the most efficient rate we are seeking. New ballgame, new rules. peace.

Click to expand...

doesnt work like that at all (or there would never be a reason to dim unless you were stressing your plants to death)

the driver reads the resistance value from the pot. all the current doesnt go thru the pot. think how hot that pot would be burning up 90% of the energy of a driver!!!!!

that said, dimming works by reducing current. cobs see what the cobs see, so the cobs in example A are identical efficiency to example B

difference is in driver efficiency.

185H-C series @ 115V is 93% efficient all the way down to 50% load*
80H-C series @ 115V doesnt crack 91%

*there are people that say that 'total load' is determined by % of driver utilization at 100% (no dimming), and this efficiency is maintained dimming all the way down. others say if you dim an array using 100% of a driver down to 40%, you read the efficiency at 40%. moot point in this case as the excellent 185H-C driver is 93% efficient at 50% as well as 100%

SSGrower said:

How extreme can you go with the "dimming" by connecting additional leds to the same driver?

Example 42v 1.5amp driver can drive 1 CXA3070 or as I am currently testing 2 in parallel, when does the bottom drop out and the driver will no longer power the led's. I have not seen a forward current limit or lower voltage limit for that matter.

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look at teh datasheet, the answer is in the CV/CC curve. and how it matches the voltage and current requirements of the load

the 42V drivers should go into constant current mode, which means voltage will drop. eventually the V will be too low to drive the cobs