What would happen if my voltage exceeded my driver?

Halfandhalf

Halfandhalf

Well-Known Member
I currently have 3x vero 29gen7 version B (~50v) on an HLG 240Hc1400b and I'm thinking about switching over to 5x D gen8's (~36v) but the max voltage of the driver is 179v and 5 of those chips is approximately 180v (182v if its 36.4v per, data sheet is unclear at that amperage). What will happen tho since the chips would be getting less voltage, would they even run or could they flicker or something?
 
cobshopgrow

cobshopgrow

Well-Known Member
i wont just dim slightly if youre above the open circuit voltage of 182V (stated in the data sheet).
the driver will go in to a special startup mode then, your leds will flicker.
it does this in the hope the leds will heat up enough so the voltage demand will become lower (heated up the voltage goes down).
it could work, youre close, but can be that if wont work in winter when its colder f.e.
saying that voltage requirements are often a little lower in real life then stated in the datasheet, you need to try.
 
ANC

ANC

Well-Known Member
undervoltage on a COB is bad news. you will see the individual LEDs inside it flicker.... until they die.
 
Halfandhalf

Halfandhalf

Well-Known Member
What's the difference between open circuit voltage and constant current region voltage? Also wouldn't dimming it lower the voltage needs? I'm probably gonna just get new drivers too but I wanna understand what would happen if I stuck with the same one. Open circuit voltage is exactly the same as 5x 36.4 chips so that's kind interesting, also according to the data sheet it's 36.4v at 1700ma and 35.8 at 1275ma, so if it's linear calculating it would come out to about 35.94v at 1400ma or 179.7 volts for 5x chips. Then again vmax at 1700ma is 39.1.v... I only ever run these in a house that's ambient is set to about 68, probably about 66 in the winter, could also dim it since I don't care about absolute max power, just want to distribute the light a bit better than I currently have.
 
cobshopgrow

cobshopgrow

Well-Known Member
the open circuit voltage is basically the headroom as these units need to operate over a wide temp range.
i once connected a HLG240 C1750, 143V max, 146V OCV, instead of a HLG320 C2100, 152V max, OCV 156V i normally used.
153V where needed for the leds (using the 2100mA driver).
it wasnt able to start the fixture, no matter what with the C1750, its going in to some fallback mode when it cant start the leds right after power up ...blink, blink.
its a bit ago, am quite sure dimming had no influence there.
meanwell desribes the fallback mode somewhere.

if you get new drivers anyway, you can test with yours first before, it should work,
youre right with your 35,94V estimation.
in real world its may even a lil lower anyway, so youre at your 179V, it will be fine.
 
cobshopgrow

cobshopgrow

Well-Known Member
am a bit out of COBs, but what you plan is like a very classic 5 pcs Cree CXB3590 240W build with exactly the driver youre using.
 
ANC

ANC

Well-Known Member
Halfandhalf said:
What's the difference between open circuit voltage and constant current region voltage? Also wouldn't dimming it lower the voltage needs? I'm probably gonna just get new drivers too but I wanna understand what would happen if I stuck with the same one. Open circuit voltage is exactly the same as 5x 36.4 chips so that's kind interesting, also according to the data sheet it's 36.4v at 1700ma and 35.8 at 1275ma, so if it's linear calculating it would come out to about 35.94v at 1400ma or 179.7 volts for 5x chips. Then again vmax at 1700ma is 39.1.v... I only ever run these in a house that's ambient is set to about 68, probably about 66 in the winter, could also dim it since I don't care about absolute max power, just want to distribute the light a bit better than I currently have.
Click to expand...
the voltage varies very little over the current range....
 
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