I’m building out a new kitchen and bath, and want to make a modular install for future maintenance. So to that end, I’d like to have connectors on both ends of every LED strip. I am building custom-length units with aluminum channel, defusers, and pigtails with a connector on each end.
The strips I buy from BTF-lighting on Amazon all have JST-SD connectors and 20-gauge wire. I thought I’d go with this because I’d get two “free” pre-made ends with every LED strip I buy. But I looked up the specs, and JST-SD is good for only 3 Amps. Some of these LED strings use a lot of power. One is about 50W per meter.
I have decent soldering and crimping skills, hot air workstation and all, so I am not trying to avoid work but it seems that if the factory puts 20 gs. JST-sd on full-length strips, maybe it is OK? I should just use that as my new standard.
If I want higher-rated connectors, what are people using?
Kitchens have a LONG lifetime, 50 years is not uncommon and I am sure that technology will evolve and stuff will fail and I will need to be able to replace parts without ripping up walls. I’m using low-voltage conduit. I’ll need to decide on a connector soon.
I don’t see a problem using them and just so you are aware, they are JST SM not SD
You can’t send that much power through 1 end of an LED strip anyways. To correctly power the strip you would need more injection points to ever reach it’s max rating. The thin copper trace in the strips, voltage drop/resistance would never allow for it. An end injection is good for like 3-5 amps max.
Thanks. I was too dumb to think about the power in each connector. End injection cuts power per connector in half, and it is unlikely I would be using a full strip as they have to be cut to size. I’m testing now and will let a worst-case build run on a bench overnight to see if anything gets warm
don’t JST SM connectors only actually go up to 22 AWG? This is where I’m getting that information, but the world of electronics connectors is a confusing place so I might be missing something
this calculator lets me get up to 4.5A (250 LEDs, WS2814 RGBW @ 12v) before suggesting I need power injection, so it would seem to me that the traces on the strip can allow more amperage through than the JST SM allows, though perhaps the datasheet is conservative and people are fine running that current through them…
I’m asking because I’m trying to figure out what connectors make the most sense for some wled projects I’m planning to work on. My assumption would be that if I inject power more frequently I would be safe still using these connectors, ex: 150 LEDs draw 2.69 amps so I could just inject power every 150 and safely use the JST SM connectors for all connections.
Can anyone who knows more than me chime in and let me know if I’m mistaken in this assumption?
The answer depends on who you are. Real engineers talk about “design margin”. Meaning that if the circuit passes 2.5 amps, they look for a connector that can do 4 or 5 amps because they want a 50% or a 100% “margin”. Same with beams, if the load is 10,000 pounds, they might spec a beam rated for 25,000. And then they are taught to think about product lifetime. Yes, it is rated at “X” when new, but how does that rating degrade over, say, 20 years, and how much margin do you want to still have? Next, is the “JST” connector actually a quality made-in-Japan part? The last batch of connectors I bought on AliExpress were fake with CCA wire that is smaller than spec’d. Junk-quality, but it still worked. A large project’s change of failure is the sum of the probability of failure of each part, and a part used right on its spec’d rating is just waiting to fail. So typically, we use a conservative margin to place the chance near zero, so even with 1,000 parts, the chance is still near zero even after 20+ years. But maybe you are not building something important, and it is just a hobby project, then do what you like as cost is likely more important than reliability.
Thanks for the reply, that makes sense. I’m not that concerned with perfect reliability like you would be for a product you’re selling at scale, but I would like to avoid accidentally starting a fire because the connector was being pushed past it’s limits.
Which is why I’ve been a bit confused not to find much talk about connectors in reference to WLED setups, it is very helpful to be able to disconnect things to move or service them at times, but JST SM connectors seem pretty inadequate if you want to minimize power injections or have any safety margin at all. Do you have any connectors you like to use for projects getting into the 4Amp plus range?
JST connectors are about the best. All you need to do is select one that handles double your peak current. If worried about fire, use an inline fuse that is rated to blow with less current than the wire is rated for.
I think you don’t read much about it is that most WLED users are hobby users making stuff for their own use. It is different it you are being paid to install in someone else’s property. The pros don’t need to ask on a forum.
But all JST connectors are rated for max 3A except the VH which is only a board-to-wire connector, not a wire-to-wire as per the wikipedia link above and looking at the JST datasheets. Injecting often enough for only 1.5A draws seems silly, so there must be some other suitable connector.
As others have mentioned, it comes down to the current you need the connector to handle.
As you get up to 3A and beyond (not hard to do when you’re driving 5V LEDs) the JST connector stops being a good choice. If you look at the problem a little differently - stop trying to use a single connector to handle both power (needs lots of current) and data (needs effectively no power), then there are many choices.
On the power side, connectors designed for batteries in RC applications routinely handle 10’s of A reliably.
For data, you could simply stick with JST and only use 2 wires (data and ground) with no worries about power handling ability at all.
It might not be as “cute” as a single JST connector, but in the long run you’ll be better off choosing the right connector for the application you need.
