Will my strips survive if my series/parallel fails?!

Hey everyone.

I'm in need of some help, please!!
Story goes, I've finally purchased some good stuff to do my own light build.

I got my hands on some bridgelux 560mm EB's gen 2 and a meanwell driver.

The strips are rated to work typically at 700mA @ 19.5V and can support a maximum of 1400mA @ 20.5V.

The driver is a XLG-150W-(60-107V)-AB type.

My plan is to run a series parallel circuit composed of 5 strips in series in two "branches", dividing the output current to the desired 700mA.

Now I am aware that I am susceptible to have thermal runaway and/or current hogging which can lead to the failure of one strip and therefore the failure of the whole "branch". This would overload my other "branch".

Now question: Taking into account the specs of the strips (they hold 1400mA) should I just pay attention to an effective passive cooling or should I be looking in protecting my circuit with other methods to prevent thermal runaway failure.?

Thank you guys! All opinions are welcome.

CanIbaS

i dont think you will need passive cooling at 700mA but its always a good idea. Everything will stay cooler an last longer with cooling.

So when connecting the strips in series what voltage do you calculate they will each have? Doesn't the voltage drop as each strip adds resistance?

You should be good. I have an EB build with gen2 1120's with a 600hlg mean-well and one of the positive push-in connectors doesn't have the best connection so I find myself time-to-time having to give that strip a little wiggle at the connector and it lights right up. No problems when the strip is off. the others carry the load just fine

Ditch the XLG and go LRS-350

BTW: EB Builds over any light out there, if you're a home grower.

Jhef said:

You should be good. I have an EB build with gen2 1120's with a 600hlg mean-well and one of the positive push-in connectors doesn't have the best connection so I find myself time-to-time having to give that strip a little wiggle at the connector and it lights right up. No problems when the strip is off. the others carry the load just fine

Ditch the XLG and go LRS-350

BTW: EB Builds over any light out there, if you're a home grower.

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Thank you for your reply. Feel better now knowing I won't burn my build.

You are right, I've been conservative with the driver... But it arrives today so for now I'll be having the strips running at their typical values. Maybe in the future I'll upgrade.

I'm lighting a 2.6x2.6 space. I believe the dank should grow fine with the (spec sheet announced) 24.000lm (10 strips).

Again, thank you @Jhef

Renfro said:

So when connecting the strips in series what voltage do you calculate they will each have? Doesn't the voltage drop as each strip adds resistance?

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This is a pretty big deal as im seeing for myself right now.

Renfro said:

So when connecting the strips in series what voltage do you calculate they will each have? Doesn't the voltage drop as each strip adds resistance?

Click to expand...

Hey,

I've calculated the 19.5V straight. Equals 97.5 which is just 91% of the driver main load of 107V. I believe that the driver is cable of handling the voltage drops.

My concern is actually more regarding the split of the current! Will the driver give 700mA equally ? Or those V drops you are talking will have an influence on it?

getogrow said:

This is a pretty big deal as im seeing for myself right now.

Click to expand...

Let me know what you find. It is my understanding that when wired in series, each strip would act as a resistor, resistors in series drop the voltage in the circuit, so you might have 60 volts going in to the first resistor, and 40 coming out into the next resistor, then 20 coming out into the next resistor... I could be wrong, maybe I am missing something.

"a series resistor circuit having N resistive components will have N-different voltages across it while maintaining a common current."

Therefore each strip thats wired in series will experience a different voltage and the current will be the same for all strips in series.

Yes, if you lose one of your parallel branches, the remaining branch/s will carry that additional current. So you would in that instance, be pushing the max current they are rated for. I doubt that would turn out well unless the cooling is capable of dissipating that much heat.

I've had BXEB Gen1 strips running full time in perpetual grow areas, at 700ma, without any sort of heatsink whatsoever for over three years.
Granted, these builds are all on constant current drivers, in series circuit, but in all my research, I've yet to see a single confirmed case of thermal runaway. Not once. Only discussion of the theoretical potential.
Thermal runaway, seems to be the "boogie man" of the DIY LED realm.
If someone has experienced it, first hand, I'd like to hear more.

Chip Green said:

I've had BXEB Gen1 strips running full time in perpetual grow areas, at 700ma, without any sort of heatsink whatsoever for over three years.
Granted, these builds are all on constant current drivers, in series circuit, but in all my research, I've yet to see a single confirmed case of thermal runaway. Not once. Only discussion of the theoretical potential.
Thermal runaway, seems to be the "boogie man" of the DIY LED realm.
If someone has experienced it, first hand, I'd like to hear more.

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im not as experienced as you guys but my electrical knowledge says your [probably correct. I have seen it but it was under extreme conditions. (500 watts to a qb 288...i think finally caused runaway......130c or higher)

Renfro said:

Let me know what you find. It is my understanding that when wired in series, each strip would act as a resistor, resistors in series drop the voltage in the circuit, so you might have 60 volts going in to the first resistor, and 40 coming out into the next resistor, then 20 coming out into the next resistor... I could be wrong, maybe I am missing something.

Click to expand...

I did not test anything after i realized i had too much resistance on the build but i can promise thats exactlty what was going on.....i was using the pcb's as connectors to parallel each strip together.
I rewired using less resistance so its fine now. Im going to test the voltage drop on longer runs to the driver and see if i lose anything. (im not expecting to lose anythihng in a 12' run .......)

I've hooked up my build. Ao far with a few hours running the temperature on the boards is low.

I haven't measured anything, voltage drops, current, etc. I'm happy with the blast I have now compared to my household led strips!

Thank you guys for your input! Let's hope this rig brings the dank!!


CanIbaS