Screw-In Barrel Adapter for LED light array gets really hot?

[zman78]

Hi All,

I have an LED Light array that had a built-in AC-DC 24v 45 watt power supply. The power supply failed so I desoldered the LED Light array power input wires from the power supply and then screwed it into barrel connector jack (ends still tinned with the original solder).

This is the barrel connect or jack https://www.amazon.com/gp/product/B07Q6YMM6F/

Then I bought an external 24Volt/3Amp power brick (with same size barrel connector output) and plugged it in.

Everything works fine, except that the screw-in barrel connector gets really hot! (145 degrees F). In fact, hot enough that the connection seems to expand, then after turning it off and cooling off -- the barrel connector doesn't make contact anymore and i have to wiggle it to make it contact again.

The LED array is 24 Volts @ 2 Amps / 45 watts. The screw-in jack is 24 Volts / 150 Watts rated. The power supply is 24 Volts / 3 Amps rated. The power supply also gets a little warm (140 degrees F) but seems to have no issues otherwise.

So the question is --

- Did i mess something up and created too much resistance in screwing the wires into the terminals?

- Is the screw-in terminal jack i bought of poor quality and just can't handle the current flowing through even though it's rated for 150 watts?

So should I still try to use the screw-in barrel terminals, or am I better off just cutting the power supply barrel plug off and directly soldering the power supply output to the LED array power-in wires?

Thanks!

[eccerr0r]

Re: Screw-In Barrel Adapter for LED light array gets really hot?

Question is where is the weak spot...
Also if you buy a barrel connector that's not quite the mate for what you need...
These barrel connectors should be able to pass 2A just fine, but only if they mesh exactly. I've also found that screw connections you need a significant amount of torque to get it just right for high current. It might be a bit easier to get the right amount of torque if you crimp a connector on the wire and then screw onto the connector.

Chop off and solder is always good, but doesn't help if you got the wrong mating connector.

So where exactly is it getting hot, the screws or the barrel or somewhere else? That's where you need to focus.

[zman78]

Re: Screw-In Barrel Adapter for LED light array gets really hot?

Thanks for the reply! I attached a photo of the attachment to help describe the situation.

I took a thermocouple and tested the temperatures at various points. Both the positive and negative screw are at 141 degrees. The metal parts of the barrel connector still showing (both the top and bottom halves) are also 141 degrees. The black/plastic parts reads 133f but that's probably just because of the poor heat transfer through the non metal material.

So it seems like the whole assembly is getting to the same temperature. I guess since all the metal pieces are touching each other they transmit the heat throughout and it's hard to pinpoint where the heat is actually coming from?

Do you think it's reasonable to try to pass 45 watts through a screw-in connector like this?

The red/white wires above are going to the LEDs. So one thought was instead of using barrel connectors I can directly solder the Red/White wires to the power supply. I.e., cut the barrel connect off the power supply (so long warranty i guess!) and solder the two wires together.

Also I did get both male/female barrel connectors from Amazon. Another possibility is to cut off the barrel connector on the power supply side and instead attach one of the amazon female barrel connectors -- at least then the barrel connectors are from the same set and presumably mate better.

I did try to tighten that screw as far as possible without stripping them. But that is with bare wire. I also just now cut off the tinned portion of the red/white wires and tried fresh bare stranded wire into the screw posts and got the same temperature issues. If you think crimping something on would help do you have a suggestion on what I should pick up to crimp onto the wire?

[diif]

Re: Screw-In Barrel Adapter for LED light array gets really hot?

There are two sizes of centre pin. 2.1mm and 2.5mm. A 2.5mm male would fit on a 2.1mm female and give you the issue you describe. Have you double checked the sizes ?

[stj]

Re: Screw-In Barrel Adapter for LED light array gets really hot?

and 2.3mm - there are huge variations on those damned plugs

[zman78]

Re: Screw-In Barrel Adapter for LED light array gets really hot?

Thanks for the suggestion, I double checked and the power supply has a 2.1mm center and 5.5mm outer dimension. Looks like it "should" match the screw-in barrel connector well. This is the exact power supply in question:

https://www.amazon.com/gp/product/B01CYIFOHE/

I had a bag of 5 of the screw-in terminals and tried swapping out to a different one in case one of them was bad, and had the same issue as well.

[eccerr0r]

Re: Screw-In Barrel Adapter for LED light array gets really hot?

Start with it cold again and see which end gets hot... too many connections here that could be suspicious...

[diif]

Re: Screw-In Barrel Adapter for LED light array gets really hot?

Thanks for the suggestion, I double checked and the power supply has a 2.1mm center and 5.5mm outer dimension. Looks like it "should" match the screw-in barrel connector well. This is the exact power supply in question:

https://www.amazon.com/gp/product/B01CYIFOHE/

I had a bag of 5 of the screw-in terminals and tried swapping out to a different one in case one of them was bad, and had the same issue as well.

Double checked how ? The Amazon adapter has spring loaded contacts in the end of the tip where as the other connectors do not.

[clearchris]

Re: Screw-In Barrel Adapter for LED light array gets really hot?

I avoid barrel connectors whenever I can, for the reasons OP stated. They tend to get hot, even under rated loads. Bad connections can lead to fire. I put xt60 connectors wherever I can, and with the new xt60e-m connectors, it's even easier to panel mount them. Only downside is the xt60em connectors use M2.5 screws which I have had to stock up on.

[eccerr0r]

Re: Screw-In Barrel Adapter for LED light array gets really hot?

Barrel connectors should work fine, after all, laptops use them all the time and they draw 3A frequently...

[zman78]

Re: Screw-In Barrel Adapter for LED light array gets really hot?

Start with it cold again and see which end gets hot... too many connections here that could be suspicious...

OK Starting with cold, I measured the following points:

P1) The screw attached to the white wire
P2) The screw attached to the red wire
P3) The exposed metal ring of the screw-in adapter side
P4) The exposed metal ring of the power supply side

They tracked pretty closely with each other, but there was a consistent temperature gap between them.

- The red screw (P2) was 3 degrees hotter than the white screw (P1).
- The white screw (P1) was ~1 degree hotter than P3.
- P3 was 2 degrees hotter than P4.

As the thing warmed up these temperature gaps stayed pretty much the same until it all reaches equilibrium at ~140 degrees.

[zman78]

Re: Screw-In Barrel Adapter for LED light array gets really hot?

Double checked how ? The Amazon adapter has spring loaded contacts in the end of the tip where as the other connectors do not.

Only that I went back to my order history and verified the size of the barrel adapter on the power supply based on their advertising. Just to make sure i didn't do a bone-head move and ordered mismatching size! I don't have any tools to actually measure it though so i'm entirely depending on their specs being correct.

[redwire]

Re: Screw-In Barrel Adapter for LED light array gets really hot?

I think your project will not work out using generic DC jacks at that high a current level.
The spring contact area is critical and a limiting factor because it's usually a flat leaf touching the barrel, and the center pin may or may not have a compression pin or just a leaf spring. Many DC jacks are only rated 0.2A

Either use quality brand-name connectors (on both ends) such as CUI or change to a different connector entirely.

[eccerr0r]

Re: Screw-In Barrel Adapter for LED light array gets really hot?

Theoretically they should reach multiple amps. I mean, look at USB, just leafs touching each other and getting more than 0.2A. Granted it depends on the construction of the plugs whether or not they can handle them. As said I have laptops drawing in excess of 3A through barrel connectors, and not the super big ones like HP and Dell, but rather the small HP and Asus...

Ultimately it's how well the two pieces mate. A strong bond will keep things cool. Also I don't know about the PCB these "screw terminal connectors" tend to reside on, if they draw a tiny track to connect the two, that too is a source of issues...

If the screw terminals are getting hotter first, you may need to torque down even more...

[diif]

Re: Screw-In Barrel Adapter for LED light array gets really hot?

Only that I went back to my order history and verified the size of the barrel adapter on the power supply based on their advertising. Just to make sure i didn't do a bone-head move and ordered mismatching size! I don't have any tools to actually measure it though so i'm entirely depending on their specs being correct.

Same size, different styles. Look inside the ends of the connectors.
The DC power supply in that link has two tiny bent metal contacts instead of a solid core in the pair of connectors.

[zman78]

Re: Screw-In Barrel Adapter for LED light array gets really hot?

Theoretically they should reach multiple amps. I mean, look at USB, just leafs touching each other and getting more than 0.2A. Granted it depends on the construction of the plugs whether or not they can handle them. As said I have laptops drawing in excess of 3A through barrel connectors, and not the super big ones like HP and Dell, but rather the small HP and Asus...

Ultimately it's how well the two pieces mate. A strong bond will keep things cool. Also I don't know about the PCB these "screw terminal connectors" tend to reside on, if they draw a tiny track to connect the two, that too is a source of issues...

If the screw terminals are getting hotter first, you may need to torque down even more...

Maybe I need to just chalk it up to the cheap connectors from an unknown brand name? I tried to crank that + terminal as much as i could and didn't get much better.

So let's say I ditch the screw-in terminals. Instead, i cut off the barrel connector from the power supply side. Does anyone know if i will get 3 wires or two wires? I saw a different power supply (NOT the one i bought!!) https://www.amazon.com/ALITOVE-100-2...dp/B01GC6VS8I/ shows there are 3 wires inside. The one i bought doesnt show a picture like this so i dont know what to expect. ***EDIT***: Oh wait i think that is the power cord to the wall that shows 3 conductors, not the 24V side the barrel connector is on, which I would expect only two on since the barrel connector itself only has 2 conductors.

So after cutting off the barrel connector from the power supply, say i want to solder the wires directly to my red/white wires in the picture instead of going through the barrel connectors. If there are 3 wires how do i figure out which one is neutral and which one is ground? I assume i wire Hot to red, Neutral to White, and ground i just don't connect?

Thanks!

[zman78]

Re: Screw-In Barrel Adapter for LED light array gets really hot?

Same size, different styles. Look inside the ends of the connectors.
The DC power supply in that link has two tiny bent metal contacts instead of a solid core in the pair of connectors.

Oh wow you're right! I took a look inside with a flashlight. The power supply has two very thin strips of conductor to make contact in its barrel plug. Whereas the same-gendered screw-in terminal has a solid conductor all around on the inside.

How did you see that from just the picture on Amazon? Do you think the heat could be because the mismatched connectors?

I guess i am better off just cutting the thing off and hard wiring it.

[eccerr0r]

Re: Screw-In Barrel Adapter for LED light array gets really hot?

Actually it still depends on its mate, but if the plug and receptacle aren't quite matched up but close, the two metal contact system is better. My Asus eeePC 12V 3A power supply is like this, so these things should pass 3A just fine like my eeePC.

Reason being, if the sizes don't match, worst case you only touch one side...

Must get matched mate for best connectivity.

[diif]

Re: Screw-In Barrel Adapter for LED light array gets really hot?

Oh wow you're right! I took a look inside with a flashlight. The power supply has two very thin strips of conductor to make contact in its barrel plug. Whereas the same-gendered screw-in terminal has a solid conductor all around on the inside.

How did you see that from just the picture on Amazon? Do you think the heat could be because the mismatched connectors?

I guess i am better off just cutting the thing off and hard wiring it.

I know DC adapters and have been dealing with jack mismatches for years. Your adapter from Amazon with the springs is the most common type.

If this is going to be a permanent install cut and solder the wires or us Wago connectors.

Centre pin is positive, but if the ends are cut off just use your multimeter on the two bare wires, it will show a - voltage if you have the leads on the wrong way round. It's probably red and white wires with red being +.

I have a pair of identical paired connectors, I am currently testing at 24v 3.6A, there is a bit of warmth in the connector after 10 minutes. How long did it take for yours to heat up ?

[zman78]

Re: Screw-In Barrel Adapter for LED light array gets really hot?

I know DC adapters and have been dealing with jack mismatches for years. Your adapter from Amazon with the springs is the most common type.

If this is going to be a permanent install cut and solder the wires or us Wago connectors.

Centre pin is positive, but if the ends are cut off just use your multimeter on the two bare wires, it will show a - voltage if you have the leads on the wrong way round. It's probably red and white wires with red being +.

I have a pair of identical paired connectors, I am currently testing at 24v 3.6A, there is a bit of warmth in the connector after 10 minutes. How long did it take for yours to heat up ?

Thanks for the info! I'm ok with making it permanent so I will cut and solder. It would have been nice to be able to swap a different power supply in and out easily (for example if this one also fails).

It jumps to around ~110 degrees within a few minutes, but then slowly gets to 140f. Maybe about 20 minutes until it's fully warm.

By the way since you know the DC power supplies well -- the one I bought, the case temperature of the brick also gets to about 140 degrees after ~20 minutes. Is that reasonable for the power draw I'm putting on it? I'll be having the LED strip on for 12-14 hrs a day. I just wanted to check if this heat level is OK for both safety and longevity. Or, if this might be a problem and I should invest in a better quality DC power adapter.

Thanks!