LED versus T5 efficiency - Page 3

Gavin · 01-29-18, 07:06 PM

re comment #19
Hi Jeff,

Most CoB LEDs I have tried have a fatal flaw. There are strings of LEDs in parallel without current regulation for the separate series strings. They try to match the forward voltage, but there are changes with aging. Also if the heatsink attachment isn't perfectly smooth there can be hot spots. Either way, over time some strings hog more current, have run away and the CoB fails. I've used a bunch and not had many of them last more than a few months, a year at best.
Let me know how these work out for you over the long term. If they are good then I'd like to know the brand. Meanwhile, I'm sticking with midpower LEDs, now up to 160 lpw.

oil pan 4 · 01-29-18, 08:57 PM

Those T5 ballast must be old.
Mine are from 2013. They draw about 50 to 55 volt amps per tube on the high output ones.
I have some intermediate output ones, my Frankenstein fixtures that use a T8 ballast left over from my T8 LED upgrade, uses about 40va per tube, looks as bright as the full powered T5 tubes and these T8 ballasts are way brighter when powering T5 tubes than they were when powering T8 tubes they supposed to be used on.

Maybe late 2017 - 2018 will be the time that LED finally surpasses T5 in efficiency at the consumer level.
But will these LEDs be as relable as T5?
The LED should last something like 50,000 hours but not if it overheats. What about the power supply, if it over heats then it's finished then too.

My T5 LED tubes came in today. I have not tried them out yet.
ATM they are substantiallymore expensive than repowering a T5 fixture.
The cheapest I have seen them is $15 per tube that's if you buy a lot of them. If you only order a few you are looking at $17 to $23 per tube.
To re ballast a T5 costs between $7 and $12 per tube. The more tubes the ballast poweres, the lower the cost.
A 6 tube T5 ballast for a 6 tube fixture can lower the cost to as little as $5 per tube.

Gavin · 02-01-18, 05:56 PM

Back to the original T5-HO topic
I have completed my testing; here are the results from my Extech Power Analyzer. Not the most accurate, but good enough for relative comparison.

Ballast is GE 454MVPS90-E maybe a few years old but still reasonably efficient.
4 tubes tested in each case, in the same fixture
GE F54W-T5-850-ECO (also a few years old so not as bright as new ones)
233 Watts PF 0.984 (tubes presumably 54*4 = 216W, rest is ballast - ~8%)
Lunera HN-T5-D-48-25W-850-G2 (nominal 3500 lumens, older G1 is only 3200lm)
114 Watts PF 0.991 ( so about 14W used by this ballast assuming tubes are close to nominal 25W)
MaxLite L24T5SE450-CG (Bypass, line voltage direct into one end, easiest to rewire)
100.6 Watts PF 0.996 (ok, so 0.6W over nominal, probably measurement error)
nominal 25W 3400 lumens each

So these T5 LED tubes both provide more than 50% savings and are brighter than my (aged) fluorescents. I only bothered to replace ballasts where the ballast had gone bad in one or both sections. I was surprised at the small difference between bypass and direct replace. With older non-power factor correcting ballasts I would replace them.
Spreadsheet with details available on request - gavin.perry (at) MeridianLighting (dot) COM

oil pan 4 · 02-02-18, 11:52 AM

I picked up some 2,800 lumen replacement LEDs and they don't appear to be putting off any where close to the light i get from my German made 54w tubes.
There appears to be a big difference in German made tubes versus chinese as they age.
My German tubes are not brand new, they are up to 3 years old.

Gavin · 02-02-18, 03:02 PM

2800 is a lot less than 3500 do I'm not surprised.
Recall I had GE ballasts and tubes. Who knows where they were made.

jeff5may · 02-02-18, 11:49 PM

I have been playing around with the epistar chips and their DC driver boards for a while. The boards are built around the pt4115 chip. Before that it was the little Cree stars that look like a snowflake. I figured out the driver boards are dimmable, either by a shunt resistance or by pwm duty cycle. I also found out that a 10k NTC thermistor makes a good "don't burn up" dimmer while testing fixtures.

The other type I like is the 12v strip light tape. I dug up the specs for what I bought and shared it in another thread recently.

oil pan 4 · 02-03-18, 03:18 AM

How much are these going to cost?

T5 HO are supposed to be up to 5,000 lumens.

I put one of these fixtures up in the foyer of our house. The wife says it's too bright and doesn't like the 4100 to 5000k light those particular tubes put off. I think I have some 3500k tubes.

jeff5may · 02-03-18, 08:23 AM

The big difference between a t5 fluorescent light and a COB light is the profile. A t5 lamp is long and skinny where the COB lights are very compact. Most of the chips up to about 10w are roughly the size of a postage stamp. The 25w to 100w chips are maybe as big as a poker chip. They are more of a point source, like a halogen or arc discharge lamp.

All the chips I have been using are built on an aluminum substrate and have mounting holes drilled in them. They all need to be mounted to a heat sink using heat sink grease. The chips also have no current limiting or regulation mechanism built in, so if you do anything stupid with them they can quickly die. I have found that processor heat sinks from obsolete desktop computers work awesome. The fans that go on them run off 12 volts, too, and the nice fans have pwm speed control just like the drive boards for the chips. Highly tinkerable.

oil pan 4 · 02-03-18, 07:44 PM

Yes I have used these before. I tried to make my own LED head lights with them years ago.

oil pan 4 · 02-06-18, 05:40 AM

I was at Sams club and found some 80 lumen per volt-amp "60w replacements".
They're getting up there.

02-03-18, 03:18 AM	#27
oil pan 4 Land owner Join Date: Nov 2012 Location: NM Posts: 1,026 Thanks: 12 Thanked 127 Times in 107 Posts	How much are these going to cost? T5 HO are supposed to be up to 5,000 lumens. I put one of these fixtures up in the foyer of our house. The wife says it's too bright and doesn't like the 4100 to 5000k light those particular tubes put off. I think I have some 3500k tubes. Last edited by oil pan 4; 02-03-18 at 05:46 AM..

01-29-18, 07:06 PM	#21
Gavin Lurking Renovator Join Date: Jul 2010 Posts: 4 Thanks: 0 Thanked 0 Times in 0 Posts	re comment #19 Hi Jeff, Most CoB LEDs I have tried have a fatal flaw. There are strings of LEDs in parallel without current regulation for the separate series strings. They try to match the forward voltage, but there are changes with aging. Also if the heatsink attachment isn't perfectly smooth there can be hot spots. Either way, over time some strings hog more current, have run away and the CoB fails. I've used a bunch and not had many of them last more than a few months, a year at best. Let me know how these work out for you over the long term. If they are good then I'd like to know the brand. Meanwhile, I'm sticking with midpower LEDs, now up to 160 lpw.

01-29-18, 08:57 PM	#22
oil pan 4 Land owner Join Date: Nov 2012 Location: NM Posts: 1,026 Thanks: 12 Thanked 127 Times in 107 Posts	Those T5 ballast must be old. Mine are from 2013. They draw about 50 to 55 volt amps per tube on the high output ones. I have some intermediate output ones, my Frankenstein fixtures that use a T8 ballast left over from my T8 LED upgrade, uses about 40va per tube, looks as bright as the full powered T5 tubes and these T8 ballasts are way brighter when powering T5 tubes than they were when powering T8 tubes they supposed to be used on. Maybe late 2017 - 2018 will be the time that LED finally surpasses T5 in efficiency at the consumer level. But will these LEDs be as relable as T5? The LED should last something like 50,000 hours but not if it overheats. What about the power supply, if it over heats then it's finished then too. My T5 LED tubes came in today. I have not tried them out yet. ATM they are substantiallymore expensive than repowering a T5 fixture. The cheapest I have seen them is $15 per tube that's if you buy a lot of them. If you only order a few you are looking at $17 to $23 per tube. To re ballast a T5 costs between $7 and $12 per tube. The more tubes the ballast poweres, the lower the cost. A 6 tube T5 ballast for a 6 tube fixture can lower the cost to as little as $5 per tube.

02-01-18, 05:56 PM	#23
Gavin Lurking Renovator Join Date: Jul 2010 Posts: 4 Thanks: 0 Thanked 0 Times in 0 Posts	Back to the original T5-HO topic I have completed my testing; here are the results from my Extech Power Analyzer. Not the most accurate, but good enough for relative comparison. Ballast is GE 454MVPS90-E maybe a few years old but still reasonably efficient. 4 tubes tested in each case, in the same fixture GE F54W-T5-850-ECO (also a few years old so not as bright as new ones) 233 Watts PF 0.984 (tubes presumably 54*4 = 216W, rest is ballast - ~8%) Lunera HN-T5-D-48-25W-850-G2 (nominal 3500 lumens, older G1 is only 3200lm) 114 Watts PF 0.991 ( so about 14W used by this ballast assuming tubes are close to nominal 25W) MaxLite L24T5SE450-CG (Bypass, line voltage direct into one end, easiest to rewire) 100.6 Watts PF 0.996 (ok, so 0.6W over nominal, probably measurement error) nominal 25W 3400 lumens each So these T5 LED tubes both provide more than 50% savings and are brighter than my (aged) fluorescents. I only bothered to replace ballasts where the ballast had gone bad in one or both sections. I was surprised at the small difference between bypass and direct replace. With older non-power factor correcting ballasts I would replace them. Spreadsheet with details available on request - gavin.perry (at) MeridianLighting (dot) COM

02-02-18, 11:52 AM	#24
oil pan 4 Land owner Join Date: Nov 2012 Location: NM Posts: 1,026 Thanks: 12 Thanked 127 Times in 107 Posts	I picked up some 2,800 lumen replacement LEDs and they don't appear to be putting off any where close to the light i get from my German made 54w tubes. There appears to be a big difference in German made tubes versus chinese as they age. My German tubes are not brand new, they are up to 3 years old.

02-02-18, 03:02 PM	#25
Gavin Lurking Renovator Join Date: Jul 2010 Posts: 4 Thanks: 0 Thanked 0 Times in 0 Posts	2800 is a lot less than 3500 do I'm not surprised. Recall I had GE ballasts and tubes. Who knows where they were made.

02-02-18, 11:49 PM	#26
jeff5may Supreme EcoRenovator Join Date: Jan 2010 Location: elizabethtown, ky, USA Posts: 2,431 Thanks: 431 Thanked 619 Times in 517 Posts	I have been playing around with the epistar chips and their DC driver boards for a while. The boards are built around the pt4115 chip. Before that it was the little Cree stars that look like a snowflake. I figured out the driver boards are dimmable, either by a shunt resistance or by pwm duty cycle. I also found out that a 10k NTC thermistor makes a good "don't burn up" dimmer while testing fixtures. The other type I like is the 12v strip light tape. I dug up the specs for what I bought and shared it in another thread recently.

02-03-18, 08:23 AM	#28
jeff5may Supreme EcoRenovator Join Date: Jan 2010 Location: elizabethtown, ky, USA Posts: 2,431 Thanks: 431 Thanked 619 Times in 517 Posts	The big difference between a t5 fluorescent light and a COB light is the profile. A t5 lamp is long and skinny where the COB lights are very compact. Most of the chips up to about 10w are roughly the size of a postage stamp. The 25w to 100w chips are maybe as big as a poker chip. They are more of a point source, like a halogen or arc discharge lamp. All the chips I have been using are built on an aluminum substrate and have mounting holes drilled in them. They all need to be mounted to a heat sink using heat sink grease. The chips also have no current limiting or regulation mechanism built in, so if you do anything stupid with them they can quickly die. I have found that processor heat sinks from obsolete desktop computers work awesome. The fans that go on them run off 12 volts, too, and the nice fans have pwm speed control just like the drive boards for the chips. Highly tinkerable.

02-03-18, 07:44 PM	#29
oil pan 4 Land owner Join Date: Nov 2012 Location: NM Posts: 1,026 Thanks: 12 Thanked 127 Times in 107 Posts	Yes I have used these before. I tried to make my own LED head lights with them years ago.

02-06-18, 05:40 AM	#30
oil pan 4 Land owner Join Date: Nov 2012 Location: NM Posts: 1,026 Thanks: 12 Thanked 127 Times in 107 Posts	I was at Sams club and found some 80 lumen per volt-amp "60w replacements". They're getting up there.