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This feels like a silly question, but I don't know the answer. How do I find an appropriate LED strip? I am looking for a flexible strip of LEDs that can be driven with apprx 65 VDC at 350mA and is 550-600mm long and no more than about 9.5mm high.

To be clear, I am not looking for a product recommendation. I am looking for a "how to find it" recommendation. Tomorrow I will likely want a completely different LED strip and I hope today's answer will still be applicable then.

This is to replace an LED strip that just burned out (the lights are very dim and some do not light at all). The strip is a flexible strip with an adhesive backing. I like the fixture and would like to replace the LED part. It is verified that the driver is okay; I have several of these light fixtures and putting a fresh one on the driver lights nicely.

There are numbers on the existing LED strip: 2835-90D (I assume this refers to 2835 type SMD LED and there are 90 of them on this strip), 591-6mm (I assume this is length-height), and 5B18C (no idea what this means but an internet search with this brings up many Alibaba pages of LED fixtures).

Anyhow, searching Digikey/Mouser/Allied/Newark/Arrow/Google has been an exercise in frustration. Maybe I am using the wrong keywords ("LED strip", "LED tape", "LED", "2835" to name a few) or maybe I am just looking in the wrong places. I suspect there is a more appropriate keyword and perhaps a more appropriate search engine.

I believe these things exist. I was able to find a model 12V-MB-CW-12M unit (Inspired LED, LLC) but of course it does not match the power supply I want to use.

It is an option to just throw all of this out and buy a new one. They are certainly cheap enough; probably less expensive to replace than to repair. But I think I can do a little bit better than the original manufacturer and I think I can find a slightly better component and I think the final assembly will be a little bit better if I do it myself. Like I said earlier, I like the fixture a lot even though I know everything else is mostly cheap junk.

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  • \$\begingroup\$ This seems likely to get closed as a shopping question, I'm afraid. \$\endgroup\$ – Hearth Feb 17 '19 at 20:07
  • \$\begingroup\$ How much work is it to throw out the driver and install a 12 or 24 V one instead? Alternatively a buck converter from 65 to 12 or 24 V? \$\endgroup\$ – winny Feb 17 '19 at 20:21
  • \$\begingroup\$ @winny It would be easy to throw out the driver and replace it with another one. I just find it hard to believe that is necessary. \$\endgroup\$ – Chris K8NVH Feb 17 '19 at 20:36
  • \$\begingroup\$ @Hearth Sadly, I agree. But I hope the moderators realize I am not so much looking for a particular "thing" but rather how to find it. (Not looking for "a fish", looking for "how to fish".) \$\endgroup\$ – Chris K8NVH Feb 17 '19 at 20:37
  • \$\begingroup\$ @ChrisK8NVH It might help if you make that clearer in your question. I'm not sure if "how to fish" would count as on topic either, but it's more so than "a fish" is. \$\endgroup\$ – Hearth Feb 17 '19 at 20:41
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White LEDstrips come in increasing many options from hundreds of Asian sources. They were initially made for automotive with 12V being 14.2V with 3 LEDs + R to operating from 9V dim to 14.2 full power but may be rated at 12V or 14.2 depending on supplier specs ( If you don't get a datasheet with specs., Buyer Beware of common seller spec. errors).

RGB types came in 5V with PWM drivers.

What does 591-6mm and 5B18C mean?

5B18C is the circuit chip array for 5x18= 90 LEDs that implies a nominal string voltage yet not given as they are usually rated by current. 5B3C is for 15 Chips. I suspect B is for parallel and C for series chips * 3V nom. so 3C is ~9V and 18C is ~ 54V THese strips are custom for luminaires and do NOT come with a series R and so intended for matched arrays with CC drivers for some panel light. enter image description here

591mm x 6mm strip is intended for luminaire ceiling panel arrays. 6mm is offered for parallel arrays of strips. 5mm is for LED TUBE replacements, 12.5mm wide 15mm etc are high power bigger LEDs, that may need a heatsink substrate. 8mm is std reel width, and 5mx8mm or 500-8mm is the standard reel size for general purpose. Other sizes include;173*6mm to 591*6mm

The 2845 chip is typically 0.5W 150mA 3.x V
The dimensions are 2.8mm x 4.5mm which is the modern metric SMD code.

White LEDs come in dozens of chip sizes that affect mA/chip, thus mW/chip and chips/m with 3SxP strings of 3x3V nom.chips in series + R current limit.

Tape size

5m x 8mm was the standard initial size, many wider tapes are available and may accommodate bigger LEDs, but these often need a heatsink substrate of Aluminum extruded strips but are suitable for bridges, buildings etc.

Voltage

Standard voltages for White were 12V,24V,36V,48V and there may be some who offer 60V and up but not yet avail. in franchised distribution. Due to the voltage drop in FPC strip copper, cascade 12V types were limited to 10m and 24V types depend on current but allowed more cascading and so on.

Power

There is a very wide range in amperage and power ratings per 5m reel. (too many to list)

Now with more current & power, results in more heat rise and the requirement to attach to aluminum backing for heatsink thermal cooling and the strips with larger chips also have wider tape.

Requirements

Your primary concerns are only Voltage, current, length and width. 60V is non-std. to me but may exist. As already suggested you can daisy-chain +-+-+-+_______ with a return wire using 12V LEDstrip and cut into length and custom wired with care.

Other Requirements

  • Most Luminaire designers are concerned with Lumens/Watt, Total Lumens, Lumens/meter, CRI ( color rendering index) 90 typ. 92 better. 88 worse. and more importantly the colour temperature warm, neutral, cool (e.g. ~2800'K, 4500'K{ANSI White}, 6000+ bluish white.
    The phosphor absorbs more power going from cool to warm, so Lumens/Watt reduces on average 15% yet most sellers cheat and give one rating for all.
  • I suggest you do NOT get Cool white or ones without any colour temp (CCT) ratings as they may be bad for eye glare.
  • don't forget heatsink requirements if your LEDstrip uses 65W/m
  • moisture protection IP65,IP67,IP68 or (better) coatings are required for outdoor use.

Conclusion

In short, you must adapt to standard ledstrips, and not waste time trying to find impossible dimensions, voltages and power levels. Also, consider that fewer high power LEDs creates more glare from higher Candella rating of each LED.

Here is one example of a supplier with a wide selection of CCT options in 48V, 19.2W/m https://www.derunledlights.com/flexible-led-strip-lights/48v-3014-280leds-m-19-2w-m-cri90-30m-reel-flexible-led-strip-light/

Although I have not used this supplier, these are far better specs than most disti's have. The reason is the market is flooded and franchise disti's like Mouser cannot be competitive to factory direct volume shipments that I get and personal low volume users don't realize what unknowns there are from EBAY and Alibaba type suppliers with no specs or tolerances.

e.g. this supplier offers "We not only can offer traditional IP65, IP67, IP68 waterproof process, but also new silicone extrusion process for IP67, IP68 and silicone neon technique in dotless frosted encapsulations. Most of our waterproof mold are private mode."

Power Supplies

Although you can run two 12V LEDstrips from 14.2 with 2 x 5m cascaded mac due to current limits, it is best to buy CC LED power supplies as the Vf tolerance in LEDs can be easily 25% or more so CV (constant voltage) may not achieve the rated current.

Vf tolerance

This Vf tolerance is solely due to the OEM LED quality tolerance and the inherent bulk resistance Rs tolerance. Some are binned to tighter than the 25% or more forward voltage tolerance. The Series R reduces the current tolerance by 1R/(3Vf+1R) for 12V stips or 25%/4=6% tolerance roughly. But some cheaper LED's may have 33% tolerance on Vf but better ones are =/-10% from improved epitaxial suppliers and LED binning. But unspecified tolerance strips can be anywhere in this range, so that's why CC sources are more accurate.

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  • \$\begingroup\$ At what point did OP ask about any of these topics you raise? \$\endgroup\$ – winny Feb 18 '19 at 10:01
  • \$\begingroup\$ @winny I am surprised you wrote that. I am teaching how to fish (to understand which specs are important) as opposed to a shopping answer and the question in the 1st sentence was " How do I find an appropriate LED strip?" Did you not learn anything from this? including questions like what is 5B18C? I see your question as lacking imagination or doh maybe experience. \$\endgroup\$ – Tony Stewart Sunnyskyguy EE75 Feb 18 '19 at 18:45
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Your LED strip may have been built specifically for that fitting and a direct replacement may not be available. 65 V isn't a common supply voltage so your power supply may be of no use.

You may be able to find 12 or 24 V strips that will fit but you will have to replace the power supply with the appropriate unit.

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  • \$\begingroup\$ This is a step in the right direction. Putting 5 such strips --12V-- in series would be 60 volts; I think that would work. \$\endgroup\$ – Chris K8NVH Feb 17 '19 at 20:47

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