Can 700 watts of LED strips grow trees???

nfhiggs

nfhiggs

Well-Known Member
Big Green Thumb said:
Okay, the crappy $20 chinese power supplies are failing. I have lost 2 24v power supplies. In both the power supplies, the NTC thermistor has cracked from the heat and blown out. This happened running them at 350-360 watts (power supplies are supposedly 360 watts). I need some ideas for different power supplies for the lighting systems. My current power supplies are only 85% efficient so an upgrade in efficiency would be nice too. A possible option for the drivers is just buying the cheap chinese power supplies rated at 500 or 600 watts - hopefully those could handle 360 watts 24/7. I do have another twin of the blown up power supplies on order. As soon as it arrives, I will open it to see the rating on the thermistor and order some to replace the burnt ones.

My overhead lighting consists of 2 - 2x4 panels with 15 strips each. Ideally I would like to run the strips up to 1 amp each for a total of 360 watts per panel. I definitely want some adjustment available so I can turn down the power in veg stage.
My side lighting is 16 33v strips so a different driver that could drive them at 1 amp would be ideal.

If you guys know of any great deals on drivers out there, please let me in on it!
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Those thermistors are known for that. You can actually install a bus wire in their place and the unit will function just fine.
 
Big Green Thumb

Big Green Thumb

Well-Known Member
nfhiggs said:
Those thermistors are known for that. You can actually install a bus wire in their place and the unit will function just fine.
Click to expand...
Okay, I'm striking out on google - what is a bus wire? Just a jumper wire in place of the thermistor? I opened another funtional power supply to try to get the value of the thermistor and it is all cracked too, so I'm unable to get the thermistor specs.
 
InTheValley

InTheValley

Well-Known Member
Dang, sure you had a feeling that would happen. I ran mine at only 200 watts, was scared to pump it up anymore. So happy i found those meanwell drivers, got 1, wanted to punch myself in the face for not getting both. Went back to get it, it was gone. Works great, runs my light rig much cooler..

Freaking $140 PS for $30, included shipping, lol, steal.

hope it works out for ya BGT.

I got the Perfect sun mini, but getting another tent, and 4 QB120's or Phantom boards for side lighting myself, using with my light i built.
 
dandyrandy

dandyrandy

Well-Known Member
Big Green Thumb said:
I'm not familiar with what a bus wire is. Off to Google I go...
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Jumper A jumper may be appropriate or it may not depending on the design. Some are meant to take an inrush of current and resistance lowers as it warms and normalizes. May be a thermal fuse? Then a jumper may be ok. I prefer quality and knowing the situation before I change a design. I'd hate to burn my house down.
 
Big Green Thumb

Big Green Thumb

Well-Known Member
dandyrandy said:
Jumper A jumper may be appropriate or it may not depending on the design. Some are meant to take an inrush of current and resistance lowers as it warms and normalizes. May be a thermal fuse? Then a jumper may be ok. I prefer quality and knowing the situation before I change a design. I'd hate to burn my house down.
Click to expand...
Yes, the problem is with the inrush thermistor. I currently have 4 of these power supplies, 2 are dead, 1 has the thermistor cracked but still functioning, and the last one is brand new running at only 100 watts that I have not opened up to look at the thermistor. There seems to be a real problem with these thermistors when running at high wattage. I will open up that newest p/s and see what the value of the thermistor is.
 
Big Green Thumb

Big Green Thumb

Well-Known Member
InTheValley said:
Dang, sure you had a feeling that would happen. I ran mine at only 200 watts, was scared to pump it up anymore. So happy i found those meanwell drivers, got 1, wanted to punch myself in the face for not getting both. Went back to get it, it was gone. Works great, runs my light rig much cooler..

Freaking $140 PS for $30, included shipping, lol, steal.

hope it works out for ya BGT.

I got the Perfect sun mini, but getting another tent, and 4 QB120's or Phantom boards for side lighting myself, using with my light i built.
Click to expand...
Not sure if you still need 12v power supplies, bet these meanwells are a steal. I wish I had a use for them:
https://www.ebay.com/itm/Mean-Well-HLG-320H-15B-Power-Supply-LED-Driver-Panel-Mount-15V-19A/192373581005?epid=673680368&hash=item2cca5be4cd:g:l8AAAOSwux5YOQNB

Edit: Actually I don't think the voltage is adjustable on the "B" model??
 
dandyrandy

dandyrandy

Well-Known Member
Big Green Thumb said:
Yes, the problem is with the inrush thermistor. I currently have 4 of these power supplies, 2 are dead, 1 has the thermistor cracked but still functioning, and the last one is brand new running at only 100 watts that I have not opened up to look at the thermistor. There seems to be a real problem with these thermistors when running at high wattage. I will open up that newest p/s and see what the value of the thermistor is.
Click to expand...
If it's series inrush then either a slightly lower ntc value or cooling it slightly would help.
 
dandyrandy

dandyrandy

Well-Known Member
Big Green Thumb said:
Yes, the problem is with the inrush thermistor. I currently have 4 of these power supplies, 2 are dead, 1 has the thermistor cracked but still functioning, and the last one is brand new running at only 100 watts that I have not opened up to look at the thermistor. There seems to be a real problem with these thermistors when running at high wattage. I will open up that newest p/s and see what the value of the thermistor is.
Click to expand...
Measure the voltage drop across it before it fails and you have the warm value with a little math. Then do a cold resistance check. Voila
 
Big Green Thumb

Big Green Thumb

Well-Known Member
Okay, I opened my newest power supply and can read the thermistor information: NTC 5D-15. Ebay $6.63 for 10. It will take a week to get them, but I have another 24v chinese power supply arriving tomorrow or thursday. I have a couple Meanwell ideas for the long term plan.
 
nfhiggs

nfhiggs

Well-Known Member
Big Green Thumb said:
Okay, I'm striking out on google - what is a bus wire? Just a jumper wire in place of the thermistor? I opened another funtional power supply to try to get the value of the thermistor and it is all cracked too, so I'm unable to get the thermistor specs.
Click to expand...
Yeah, just a jumper wire.
 
nfhiggs

nfhiggs

Well-Known Member
dandyrandy said:
Jumper A jumper may be appropriate or it may not depending on the design. Some are meant to take an inrush of current and resistance lowers as it warms and normalizes. May be a thermal fuse? Then a jumper may be ok. I prefer quality and knowing the situation before I change a design. I'd hate to burn my house down.
Click to expand...
Yeah it generally functions as a thermal fuse and/or inrush current limiter. The power supply (at least all the ones I have seen) will function perfectly well without them. I use these types of supplies and I generally limit them to below 300W. They run much cooler that way.
 
dandyrandy

dandyrandy

Well-Known Member
nfhiggs said:
Yeah it generally functions as a thermal fuse and/or inrush current limiter. The power supply (at least all the ones I have seen) will function perfectly well without them. I use these types of supplies and I generally limit them to below 300W. They run much cooler that way.
Click to expand...
If it's a series inrush device it will not work if open. If its a series fuse it will not work if open. If a parallel mov or other device it will work if open. Normally it limits inrush (if in series) and then the resistance lowers as it warms up. So if ran at the top of current range the power dissipation may be too much for the device. Switching supplies have a bridge rectifier and filter caps that create a DC buss of around 160vdc to allow the supply to quickly modulate the buss via powerfets to create various DC voltages through small higher frequency transformers. Usually 50kc's for good ones these days. This allows physically smaller supplies given the current compared to 60 cycle ac supplies. I used to work on equipment from the 70's which had a 5 volt 100 amp supply as well as others. Switching frequency was 15kcs. 100 pounds. Had to be repaired to the component level. Still running today probably. I'm retired now.
 
Big Green Thumb

Big Green Thumb

Well-Known Member
dandyrandy said:
If it's a series inrush device it will not work if open. If its a series fuse it will not work if open. If a parallel mov or other device it will work if open. Normally it limits inrush (if in series) and then the resistance lowers as it warms up. So if ran at the top of current range the power dissipation may be too much for the device. Switching supplies have a bridge rectifier and filter caps that create a DC buss of around 160vdc to allow the supply to quickly modulate the buss via powerfets to create various DC voltages through small higher frequency transformers. Usually 50kc's for good ones these days. This allows physically smaller supplies given the current compared to 60 cycle ac supplies. I used to work on equipment from the 70's which had a 5 volt 100 amp supply as well as others. Switching frequency was 15kcs. 100 pounds. Had to be repaired to the component level. Still running today probably. I'm retired now.
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You know, I understand almost every word you typed, but I have no idea what that paragraph means! LOL.

J/k. These cheap power supplies have the bridge rectifier and filter caps, etc on the high voltage input side as you said. And that component that failed in 2 of them is definitely an inrush thermistor. So, if i just installed a jumper wire, I suppose the problem would be when the unit is first powered on, it would draw way more current charging the capacitors than the circuit is designed for, correct? Is there an upgraded higher capacity inrush thermistor or some other way to upgrade these to not overheat when driven to the maximum rated output?
 
dandyrandy

dandyrandy

Well-Known Member
Big Green Thumb said:
You know, I understand almost every word you typed, but I have no idea what that paragraph means! LOL.

J/k. These cheap power supplies have the bridge rectifier and filter caps, etc on the high voltage input side as you said. And that component that failed in 2 of them is definitely an inrush thermistor. So, if i just installed a jumper wire, I suppose the problem would be when the unit is first powered on, it would draw way more current charging the capacitors than the circuit is designed for, correct? Is there an upgraded higher capacity inrush thermistor or some other way to upgrade these to not overheat when driven to the maximum rated output?
Click to expand...
Yep. I didn't Google the part no you posted but you could nget one that is slightly lower resistance at warm up. Less resistance less power dropped across it. That being said if it's near another device that gives off heat it doesn't help. If there is room solder it in flying lead style. Leave some distance between the PC board and the device. That will help a bit. The legs can help cool it a bit plus more air circulation. That's the way the surface mount LEDs cool is through the leads. And then transferred to the solder connection. I see these fail in some things I work on.
 
Big Green Thumb

Big Green Thumb

Well-Known Member
So according to what I have read (https://datasheet.lcsc.com/szlcsc/NTC-5D-7_C5385.pdf) these NTC 5d-15 thermistors are 5 ohm at 25* Celcius and 15 mm in diameter. Would a larger diameter thermistor be more durable since it is bigger and should be able to dissipate heat better? If I can find 5d- 22 or 30 mm, would they be better?

edit,
It looks like the 20 mm are rated at 7 amp, where the 15mm are 6 amp. I ordered up a few 5d-20's too.
 
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dandyrandy

dandyrandy

Well-Known Member
Big Green Thumb said:
So according to what I have read (https://datasheet.lcsc.com/szlcsc/NTC-5D-7_C5385.pdf) these NTC 5d-15 thermistors are 5 ohm at 25* Celcius and 15 mm in diameter. Would a larger diameter thermistor be more durable since it is bigger and should be able to dissipate heat better? If I can find 5d- 22 or 30 mm, would they be better?

edit,
It looks like the 20 mm are rated at 7 amp, where the 15mm are 6 amp. I ordered up a few 5d-20's too.
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Yep then leave a little Xtra above the board. Should be good.
 
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