Overcurrent protection techniques

I am trying to better understand protecting LEDs from overcurrent. I have considered the idea of using low-current breakers(but the lowest I can find is 2.0A, so not low enough for individual strips for example). Then there's also inrush current limiters(but they have a resistance, so they're going to drop Vout by a bit(depending on their resistance)). I'm not sure if this means one must size a driver with the voltage drop factored-in. So if the limiter has a resistance that causes the Vout to drop, wouldn't that mean to run the diodes at the right voltage one might need something like a 30V driver instead of a 28V driver or whatever they're supposed to use? There are also shunts, fuses, and fuse wires among other things I probably don't know about....

Who among us here uses some means of over-current protection on their strips, cobs, etc? If so, what kind?

Manual voltage regulation on A-type dimming meanwell drivers: set the voltage in such a way your chips can only draw the amps you want.

It you attempt to overcurrent protect strips, if one bails due to the "breaker" the others would have to carry those amps thus they all bail. So you need the current limitation to happen at the driver.

Renfro said:

It you attempt to overcurrent protect strips, if one bails due to the "breaker" the others would have to carry those amps thus they all bail. So you need the current limitation to happen at the driver.

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If each one is on overcurrent protection, wouldn't the current limiters stop the others from suffering overcurrent if one of them fails? Sure, it means they all shut off, but they don't fry right? I can get current inrush limiters that are 700ma or less so if one was on each strip wouldn't it prevent each strip from passing the max current level(assuming it to be 700ma like the strips I am looking at right now).

What if I wire one of these in series with each strip?

Problem with over current protection of LED is they are very sensitive and are likely to fry before the current limiting device shuts it down.

Experimentation will be required, probably cooking some chips in the process.

Op: read my reply above: set voltage on your. A-dimming meanwell to the lowest possible setting without lowering light output. See what happens if you remove a string in your parallel circuit, current per string wont go up as its throttled by voltage. This is the way to do what youre talking about, not fuses.

When running multiple strips in parallel, if one strip dies (open circuit) then the other strips will carry the excess amperage. If you are driving them hard then that won't end well. If you don't drive them really hard then you could lose a strip and probably catch the problem before you cook off the rest of the strips. Another benefit of driving your chips softly and using more of them is they run more efficiently and require less of a heatsink to dissipate the heat. You also get more points of light and hit the plants from more angles, better spread. All in all I would always prefer to run the chips softly, it does mean buying more strips and more aluminum but it is the way to go. If you wanna push them hard I would always want at least enough headroom that if one strip dies the others can carry the extra current without frying.

Renfro said:

When running multiple strips in parallel, if one strip dies (open circuit) then the other strips will carry the excess amperage.

Click to expand...

This is true but only to the point were the driver has enough voltage to run the other strips harder; if you limit the voltage appropriately from the driver then the remaining strips wont take the extra current.

Rocket Soul said:

This is true but only to the point were the driver has enough voltage to run the other strips harder; if you limit the voltage appropriately from the driver then the remaining strips wont take the extra current.

Click to expand...

In electrical terms "current" expresses amperage specifically.

Rocket Soul said:

Op: read my reply above: set voltage on your. A-dimming meanwell to the lowest possible setting without lowering light output. See what happens if you remove a string in your parallel circuit, current per string wont go up as its throttled by voltage. This is the way to do what youre talking about, not fuses.

Click to expand...

Sorry for any confusion, but what if you don't have an A-dimming MeanWell driver? I do own one, so this is somewhat hypothetical, but there's so many thousands of different drivers to pick from.

You can also get a dimmable dc-dc/buck driver inorder to fine tune your voltage and connect it to your driver in order to get voltage regulation

Renfro said:

When running multiple strips in parallel, if one strip dies (open circuit) then the other strips will carry the excess amperage. If you are driving them hard then that won't end well. If you don't drive them really hard then you could lose a strip and probably catch the problem before you cook off the rest of the strips. Another benefit of driving your chips softly and using more of them is they run more efficiently and require less of a heatsink to dissipate the heat. You also get more points of light and hit the plants from more angles, better spread. All in all I would always prefer to run the chips softly, it does mean buying more strips and more aluminum but it is the way to go. If you wanna push them hard I would always want at least enough headroom that if one strip dies the others can carry the extra current without frying.

Click to expand...

Renfro said:

In electrical terms "current" expresses amperage specifically.

Click to expand...

What im saying is that the excess current from the missing strip being routed thru the other strings in the parallel circuit is dependent on the driver having sufficient voltage overhead to be able to power the rest of the strips at the new higher current. If you limit this voltage the spare amps have nowhere to go.
In this case its better to think about the strips drawing current, rather than the driver pushing current.

KlompenOG said:

Sorry for any confusion, but what if you don't have an A-dimming MeanWell driver? I do own one, so this is somewhat hypothetical, but there's so many thousands of different drivers to pick from.

Click to expand...

you will be fine with any CC, B type driver also if you layout your fixture accordingly.
just take in to account that all remaining strips you drive in parallel can take the current if one or two go down (latest then you should see it...), or drive more in series to avoid all possibilities of uneven current distribution.

layout your lamp right and you shouldnt need any further fuses.
i would be carefull anyway putting too much unknowen stuff in to the led circuit.

btw. for your notebook powersupplies, same principle, use many strips in parallel so the 8A will be distributed over a good amount, if one goes down....
the voltage will limit itself, VxA=W, the driver will give about what is labeled, so if A is too high V will go down, even on a non special LED driver.
a real led driver would be of course always my first choice.

Rocket Soul said:

This is true but only to the point were the driver has enough voltage to run the other strips harder; if you limit the voltage appropriately from the driver then the remaining strips wont take the extra current.

Click to expand...

I think your getting parallel and series confused.

When I was learning this stuff the instructor often used water analogies and they usually work very well.

Driver is 20L bucket with a 15cm hole
LED strips are 3L buckets with a 10cm hole
10cm hole is the LED maximum amp rating
Water filling in the 3L buckets is heat
Spilling is device failure


Drill one 15cm hole in the bottom of 20L bucket and place a 15cm Y connector in it.
Then place the 3L buckets under the two ends of the Y connector.
When you dump 20L of water into the bucket it flows though the Y connector into the two 3L buckets and is drained by the 10cm holes.

Now plug one of the bottom Y connections and repeat. The water is now coming out of one 15cm hole instead of two and the bucket still drains at the same rate. The liters per minute (amps) has not changed, nor has the pressure inside the tube leaving the bucket changed (volts).

The 3L bucket will soon be overwhelmed and spill over.

7CardBud said:

I think your getting parallel and series confused.

When I was learning this stuff the instructor often used water analogies and they usually work very well.

Driver is 20L bucket with a 15cm hole
LED strips are 3L buckets with a 10cm hole
10cm hole is the LED maximum amp rating
Water filling in the 5L buckets is heat
Spilling is device failure


Drill one 15cm hole in the bottom of 20L bucket and place a 15cm Y connector in it.
Then place the 3L buckets under the two ends of the Y connector.
When you dump 20L of water into the bucket it flows though the Y connector into the two 3L buckets and is drained by the 10cm holes.

Now plug one of the bottom Y connections and repeat. The water is now coming out of one 15cm hole instead of two and the bucket still drains at the same rate. The liters per minute (amps) has not changed, nor has the pressure inside tube leaving the bucket changed (volts).

The 3L bucket will soon be overwhelmed and spill over.

Click to expand...

Im not mixing them up. I do understand the analogy, but its not really that good. Thing is the forward voltage of the chip/strip will change as current increases. In your analogy the size of the wholes are static when if it was true to reality they would have to change with increased pressure. Lets try this again without the water analogy:
Lets say you have some strips that will draw exactly 1Amp at exactly 36V and its forward voltage goes up to 37V at 2 amps.
You also have a driver with a nominal voltage of 36V and precise voltage regulation. Driver can output 10 Amps max.

Setup 3 strips in parallel and cap the driver voltage at exactly 36V. How many amps per strip when you turn on the driver? 1A: The driver wont be able to give full output as it can power any more amps to each strip unless voltage of the driver goes up (or fV of the strip goes down, something that may happen slightly if and when the chips increase temps).

Now remove one strip. What happens? The driver will still be at 36V so the amps per strip is still 1, cant go higher without higher voltage.

the way you describe it its the driver thats pushing the strips, instead of what is really the strips drawing current from the driver.

cobshopgrow said:

you will be fine with any CC, B type driver also if you layout your fixture accordingly.
just take in to account that all remaining strips you drive in parallel can take the current if one or two go down (latest then you should see it...), or drive more in series to avoid all possibilities of uneven current distribution.

layout your lamp right and you shouldnt need any further fuses.
i would be carefull anyway putting too much unknowen stuff in to the led circuit.

btw. for your notebook powersupplies, same principle, use many strips in parallel so the 8A will be distributed over a good amount, if one goes down....
the voltage will limit itself, VxA=W, the driver will give about what is labeled, so if A is too high V will go down, even on a non special LED driver.
a real led driver would be of course always my first choice.

Click to expand...

Thanks, I am still trying to learn the weird relationship between diodes and their power supply; they're not quite resistors, not capacitors, not transformers, and really not even completely like other semiconductor products. For such a simple device, the nuance of it can be surprisingly complicated. I know many strips/tape lights have resistors on them but the EB strips don't seem to, and honestly I haven't learned all this enough to know what all the consequences of that are.

Interestingly enough, I found a LCD display that shows voltage/wattage/amperage/etc that is wired in series with the circuit and allows you to set voltage/current cutoff levels. They also sell some that are wired in parallel and use a toroidal inductor as a sensor that you run one of your leads through, but those can't cut power. One of these days I'm going to set up an Arduino that just handles all of this crap in one device.

KlompenOG said:

Thanks, I am still trying to learn the weird relationship between diodes and their power supply; they're not quite resistors, not capacitors, not transformers, and really not even completely like other semiconductor products. For such a simple device, the nuance of it can be surprisingly complicated. I know many strips/tape lights have resistors on them but the EB strips don't seem to, and honestly I haven't learned all this enough to know what all the consequences of that are.

Interestingly enough, I found a LCD display that shows voltage/wattage/amperage/etc that is wired in series with the circuit and allows you to set voltage/current cutoff levels. They also sell some that are wired in parallel and use a toroidal inductor as a sensor that you run one of your leads through, but those can't cut power. One of these days I'm going to set up an Arduino that just handles all of this crap in one device.

Click to expand...

Please link your gadget

Yeah sorry, was having a hard time finding the tabs after my kid messed with my computer.

The one with built-in shunt and which is possibly in series is this one:


Then there's this other style that is more common but is definitely parallel-wired:


There's also these external shunt types:

KlompenOG said:

Yeah sorry, was having a hard time finding the tabs after my kid messed with my computer.

The one with built-in shunt and which is possibly in series is this one:

DC 20a 7- 100v LCD Digital Watt Current Power Voltage Meter Ammeter Voltmeter US for sale online | eBay

Find many great new & used options and get the best deals for DC 20a 7- 100v LCD Digital Watt Current Power Voltage Meter Ammeter Voltmeter US at the best online prices at eBay! Free shipping for many products!

www.ebay.com

Then there's this other style that is more common but is definitely parallel-wired:

KNACRO Current Voltage Amperage Power Energy Panel Meter LCD Digital Display CT | eBay

Find many great new & used options and get the best deals for KNACRO Current Voltage Amperage Power Energy Panel Meter LCD Digital Display CT at the best online prices at eBay! Free shipping for many products!

www.ebay.com

There's also these external shunt types:

DC 6.5-100V 0-100A LCD Display Digital Current Voltage Power Energy Meter | eBay

Find many great new & used options and get the best deals for DC 6.5-100V 0-100A LCD Display Digital Current Voltage Power Energy Meter at the best online prices at eBay! Free shipping for many products!

www.ebay.com

Click to expand...

I love the first one: nice range in voltage and decent price.

Am I missing something here? Are you against fuses or are you motived to build some sort of LED Rube Goldberg machine?