• Here is a link to the full explanation: https://rollitup.org/t/welcome-back-did-you-try-turning-it-off-and-on-again.1104810/

can you 'trick' a constant current driver with parallel strings?

BOBBY_G

BOBBY_G

Well-Known Member
what if you took a hlg-185-c1400 that was maxed out with (4) 3590s, and put 2 parallel strings of (4)3590s.

i would imagine it would meet the voltage spec but max out on current and not deliver above 700ish mA. but they might not light at all. or the voltage might rise due to the paralle strings- perhaps you could only run 2 strings of 3

and please dont tell me to just buy a 700mA driver- the idea was to be able to start with a 1400mA driver and still retain full use of it as cobs are added and current dropped to improve efficiency
 
kmog33

kmog33

Well-Known Member
BOBBY_G said:
what if you took a hlg-185-c1400 that was maxed out with (4) 3590s, and put 2 parallel strings of (4)3590s.

i would imagine it would meet the voltage spec but max out on current and not deliver above 700ish mA. but they might not light at all. or the voltage might rise due to the paralle strings- perhaps you could only run 2 strings of 3

and please dont tell me to just buy a 700mA driver- the idea was to be able to start with a 1400mA driver and still retain full use of it as cobs are added and current dropped to improve efficiency
Click to expand...
Technically should work with 2 parallel strings. But I'm not 100%


Sent from my iPhone using Tapatalk
 
mc130p

mc130p

Well-Known Member
BOBBY_G said:
what if you took a hlg-185-c1400 that was maxed out with (4) 3590s, and put 2 parallel strings of (4)3590s.

i would imagine it would meet the voltage spec but max out on current and not deliver above 700ish mA. but they might not light at all. or the voltage might rise due to the paralle strings- perhaps you could only run 2 strings of 3

and please dont tell me to just buy a 700mA driver- the idea was to be able to start with a 1400mA driver and still retain full use of it as cobs are added and current dropped to improve efficiency
Click to expand...
the short answer is no. the driver can only deliver so much power to a circuit. a constant voltage power supply will be appropriate for a parallel circuit of COBs, which is not recommended by the manufacturer.
 
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BOBBY_G

BOBBY_G

Well-Known Member
well im not trying to deliver more than 200W. im trying to deliver the same 200W to more COBs

also can you elaborate on "a parallel circuit of COBs, which is not recommended by the manufacturer"?
 
frica

frica

Well-Known Member
In a parallel circuit, if one cob fails, or a string gets loose then the other COBs suddenly get an extra dose of current.

In a best case scenario your heat sink does the job well enough to cool the now more powerful COBs, in a worst case scenario your other COBs fail and possibly burn.
It's not recommended because it's less safe.

In a normal series if one wire goes loose or a COB fails there's no full circuit so nothing can really go wrong.
 
alesh

alesh

Well-Known Member
BOBBY_G said:
well im not trying to deliver more than 200W. im trying to deliver the same 200W to more COBs

also can you elaborate on "a parallel circuit of COBs, which is not recommended by the manufacturer"?
Click to expand...
It's possible and totally safe because the worst case scenario is 1.4A which 3590 can easily handle. The voltage will drop somewhat so you'll get about 185W output from the driver.
 
BOBBY_G

BOBBY_G

Well-Known Member
frica said:
In a parallel circuit, if one cob fails, or a string gets loose then the other COBs suddenly get an extra dose of current.

In a best case scenario your heat sink does the job well enough to cool the now more powerful COBs, in a worst case scenario your other COBs fail and possibly burn.
It's not recommended because it's less safe.

In a normal series if one wire goes loose or a COB fails there's no full circuit so nothing can really go wrong.
Click to expand...

got it. confident enough in my soldering and the fact that any heatsink i have there is at least 100% oversized that if a wire comes loose ts not catastrophic
 
P

PurpleBuz

Well-Known Member
Thats an interesting config, cool idea.

8 cxb3590 at 700ma and 33Vf (off chart extrapolation) == 286Vf
The hlg 185 at 700ma handles 286V.
Great Scott that's within 2 Volts!

and as alesh said totally safe. If one string fails, the other string ends up running at 1400ma.

what I wonder is if 4 parallel strings (4 strings, 2 cobs each) has any advantage
 
BOBBY_G

BOBBY_G

Well-Known Member
well im about to build my first array and i cant get over the lack of flexibility of the constant current drivers. if i buy 1400mA drivers and want to add cobs later and drop to 700 ma, i have to buy more drivers and use the existing 1400s at half capacity.

its driving me toward the 320H and 600H series which are more flexible
 
FranJan

FranJan

Well-Known Member
BOBBY_G said:
well im about to build my first array and i cant get over the lack of flexibility of the constant current drivers. if i buy 1400mA drivers and want to add cobs later and drop to 700 ma, i have to buy more drivers and use the existing 1400s at half capacity.

its driving me toward the 320H and 600H series which are more flexible
Click to expand...
You may be more interested in different types of power supplies.



Also remember there are Buck and Boost drivers to add and remove voltages and amps and that they can be added to your existing drivers/circuits and they are a much cheaper option than buying new drivers. The downside is the overall system efficiency of your grow-room will suffer since dedicated LED drivers like MWells are more efficient but that's the price you pay for flexibility. The important part is they don't, or at least they shouldn't, effect your light's radiometric output and efficacy. You can get exceptionally efficient bench power supplies but again that's $$$ and you have to ask yourself if you're in it for the long haul then.
 
BOBBY_G

BOBBY_G

Well-Known Member
well the meanwell HLG-600H-36B is more efficient than anything else in the 185, 240, 0r 320 series and can run any of the following combinations of cobs at full utility with a simple rewire

6x100W
8x75W
12x50W
24x25W

you get the idea
 
bassman999

bassman999

Well-Known Member
BOBBY_G said:
well the meanwell HLG-600H-36B is more efficient than anything else in the 185, 240, 0r 320 series and can run any of the following combinations of cobs at full utility with a simple rewire

6x100W
8x75W
12x50W
24x25W

you get the idea
Click to expand...
I agree, but am weary to use a driver with that much current, my poor soldering could kill a group of cobs
 
mc130p

mc130p

Well-Known Member
BOBBY_G said:
well the meanwell HLG-600H-36B is more efficient than anything else in the 185, 240, 0r 320 series and can run any of the following combinations of cobs at full utility with a simple rewire

6x100W
8x75W
12x50W
24x25W

you get the idea
Click to expand...
I think you would eventually run into a problem where the effective resistance of your circuit is too low and the driver senses an over-current condition, as it cannot provide a low enough output voltage for the ouput current, Vout = I*Reff

Here is the datasheet:http://www.mouser.com/ds/2/260/HLG-600H-spec-369421.pdf

The important part, note 4 pertaining to over-current protection:
NOTE
4. Constant current operation region is within 50%~100% rated output voltage. This is the suitable operation region for LED rel
ated applications, but please reconfirm special electrical requirements for some specific system design.
 
mc130p

mc130p

Well-Known Member
BOBBY_G said:
well were still at 33V at 25W that doesnt seem all that low
Click to expand...
if the demands of the (any) circuit are able to be supplied by the driver then it will work, but you're not "tricking" anything, haha
 
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BOBBY_G

BOBBY_G

Well-Known Member
yeah i wasnt trying to pull a fast one on it

::hooks driver up to balls and takes joyride::

i guess i was just curious of real world experience and too lazy to calc it out using ohms law
 
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