Defragment SSD?

Linea Recta wrote:
"Paul" schreef in bericht
...
mike wrote:
On 7/10/2014 11:56 AM, Wildman wrote:
On Thu, 10 Jul 2014 11:42:03 -0700, David E. Ross wrote:

I have a 100 GB solid-state drive with not quite 60 GB used. The
Windows defrag tool (dfrgui.exe) says it is 7% fragmented. Since
it is
solid-state, however, does defragmenting really mean anything?

The drive is Western Digital WD10EZEX-75ZF5A0.

The main purpose of defraging is to minimize hard drive
head seek time. Since the SSD does not have heads, there
is no benefit.


While I agree with the statement about not degfragging...

I researched SSD's a while back and decided not to implement one.
There were numerous articles about SSD's being fast at first,
but slowing dramatically with use. Don't remember the term, but
there was a process to restore the speed. Don't think it was
defragmenting as we know it, but it did rearrange stuff in the flash
and required periodic fixup.
Had something to do with the fact that data is written in blocks.
When you have something in every block, your only option is to read
the block, change it, write it all back. Not the same process as
mechanical seeking, but has similar symptoms.

Maybe someone can enlighten us.

TRIM is a feature which allows the OS to tell the
SSD drive, what sectors are no longer in usage. It
adds to the pool of free sectors that can be used
for data rearrangement.

The SSD drive itself, has one or two processors inside.
And firmware. The SSD works behind the scenes. In fact,
if you leave the computer running, the SSD can do write
operations to itself all night long. It you degraded the
SSD by doing a random 4KB write test ("hammered it"), a
good SSD will spend the whole night rearranging the blocks
to take up the least space. And leave as many whole free
blocks for tomorrow. By tomorrow, write performance will
be returned to the proper level again. Without such
behind-the-scenes maintenance, the write performance
might end up at 70% or 50% of the "good" value.

Why would it do that ? It consolidates small data objects,
in the larger flash structures. Flash storage structures
are inherently larger than the sizes that OSes like.
OSes may like 512 bytes or 4K bytes, and such things
are too small for flash. Maybe you use 4K bytes in an
flash area that is a megabyte in size. So the processors
inside the SSD drive, they rearrange the data, and pack
it better. The SSD has a level of indirection, a lookup
table, that maps external LBA, to internal flash location.
And so it can move things behind the scenes, and to the
external observer, they still can be read at the same LBA
as before.

Some of the Anandtech articles, go into proper technical
terminology for this stuff.




SSD may be faster, but I believe that life span of an SSD is stil less
than that of a conventional hard disk? That's the main reason for me not
to touch SSD for the time being...

I think a modern SSD could beat my last batch of Seagate 500GB drives.
They were lasting a year.

I have mechanical drives here, with power-on-hours of 15,000 hours,
with "not a scratch on them", meaning the SMART stats are still
clean. I can't understand why there is so much difference in
behavior. Lots of that stuff must be done with robotics, to
keep things clean. It's not like someone forgot to wear
a hair net when assembling my 500GB drives :-)

Paul

"Paul" schreef in bericht
...
Linea Recta wrote:
"Paul" schreef in bericht
...
mike wrote:
On 7/10/2014 11:56 AM, Wildman wrote:
On Thu, 10 Jul 2014 11:42:03 -0700, David E. Ross wrote:

I have a 100 GB solid-state drive with not quite 60 GB used. The
Windows defrag tool (dfrgui.exe) says it is 7% fragmented. Since it
is
solid-state, however, does defragmenting really mean anything?

The drive is Western Digital WD10EZEX-75ZF5A0.

The main purpose of defraging is to minimize hard drive
head seek time. Since the SSD does not have heads, there
is no benefit.


While I agree with the statement about not degfragging...

I researched SSD's a while back and decided not to implement one.
There were numerous articles about SSD's being fast at first,
but slowing dramatically with use. Don't remember the term, but
there was a process to restore the speed. Don't think it was
defragmenting as we know it, but it did rearrange stuff in the flash
and required periodic fixup.
Had something to do with the fact that data is written in blocks.
When you have something in every block, your only option is to read
the block, change it, write it all back. Not the same process as
mechanical seeking, but has similar symptoms.

Maybe someone can enlighten us.

TRIM is a feature which allows the OS to tell the
SSD drive, what sectors are no longer in usage. It
adds to the pool of free sectors that can be used
for data rearrangement.

The SSD drive itself, has one or two processors inside.
And firmware. The SSD works behind the scenes. In fact,
if you leave the computer running, the SSD can do write
operations to itself all night long. It you degraded the
SSD by doing a random 4KB write test ("hammered it"), a
good SSD will spend the whole night rearranging the blocks
to take up the least space. And leave as many whole free
blocks for tomorrow. By tomorrow, write performance will
be returned to the proper level again. Without such
behind-the-scenes maintenance, the write performance
might end up at 70% or 50% of the "good" value.

Why would it do that ? It consolidates small data objects,
in the larger flash structures. Flash storage structures
are inherently larger than the sizes that OSes like.
OSes may like 512 bytes or 4K bytes, and such things
are too small for flash. Maybe you use 4K bytes in an
flash area that is a megabyte in size. So the processors
inside the SSD drive, they rearrange the data, and pack
it better. The SSD has a level of indirection, a lookup
table, that maps external LBA, to internal flash location.
And so it can move things behind the scenes, and to the
external observer, they still can be read at the same LBA
as before.

Some of the Anandtech articles, go into proper technical
terminology for this stuff.




SSD may be faster, but I believe that life span of an SSD is stil less
than that of a conventional hard disk? That's the main reason for me not
to touch SSD for the time being...

I think a modern SSD could beat my last batch of Seagate 500GB drives.
They were lasting a year.


You're joking? That's outrageous. And you had waranty I suppose?
Reading that I think I've been very lucky up till now with my drives.
They're all older than 10 years. But I never waste much time defragmenting
or scanning. I've read some people who defragment for a whole night long
daily or weekly and that of course causes a lot of wear and tear...



--


|\ /|
| \/ |@rk
\../
\/os

On 7/11/2014 2:22 PM, Linea Recta wrote:
"Paul" schreef in bericht
...
Linea Recta wrote:
"Paul" schreef in bericht
...
mike wrote:
On 7/10/2014 11:56 AM, Wildman wrote:
On Thu, 10 Jul 2014 11:42:03 -0700, David E. Ross wrote:

I have a 100 GB solid-state drive with not quite 60 GB used. The
Windows defrag tool (dfrgui.exe) says it is 7% fragmented. Since
it is
solid-state, however, does defragmenting really mean anything?

The drive is Western Digital WD10EZEX-75ZF5A0.

The main purpose of defraging is to minimize hard drive
head seek time. Since the SSD does not have heads, there
is no benefit.


While I agree with the statement about not degfragging...

I researched SSD's a while back and decided not to implement one.
There were numerous articles about SSD's being fast at first,
but slowing dramatically with use. Don't remember the term, but
there was a process to restore the speed. Don't think it was
defragmenting as we know it, but it did rearrange stuff in the flash
and required periodic fixup.
Had something to do with the fact that data is written in blocks.
When you have something in every block, your only option is to read
the block, change it, write it all back. Not the same process as
mechanical seeking, but has similar symptoms.

Maybe someone can enlighten us.

TRIM is a feature which allows the OS to tell the
SSD drive, what sectors are no longer in usage. It
adds to the pool of free sectors that can be used
for data rearrangement.

The SSD drive itself, has one or two processors inside.
And firmware. The SSD works behind the scenes. In fact,
if you leave the computer running, the SSD can do write
operations to itself all night long. It you degraded the
SSD by doing a random 4KB write test ("hammered it"), a
good SSD will spend the whole night rearranging the blocks
to take up the least space. And leave as many whole free
blocks for tomorrow. By tomorrow, write performance will
be returned to the proper level again. Without such
behind-the-scenes maintenance, the write performance
might end up at 70% or 50% of the "good" value.

Why would it do that ? It consolidates small data objects,
in the larger flash structures. Flash storage structures
are inherently larger than the sizes that OSes like.
OSes may like 512 bytes or 4K bytes, and such things
are too small for flash. Maybe you use 4K bytes in an
flash area that is a megabyte in size. So the processors
inside the SSD drive, they rearrange the data, and pack
it better. The SSD has a level of indirection, a lookup
table, that maps external LBA, to internal flash location.
And so it can move things behind the scenes, and to the
external observer, they still can be read at the same LBA
as before.

Some of the Anandtech articles, go into proper technical
terminology for this stuff.




SSD may be faster, but I believe that life span of an SSD is stil
less than that of a conventional hard disk? That's the main reason
for me not to touch SSD for the time being...

I think a modern SSD could beat my last batch of Seagate 500GB drives.
They were lasting a year.


You're joking? That's outrageous. And you had waranty I suppose?
Reading that I think I've been very lucky up till now with my drives.
They're all older than 10 years. But I never waste much time
defragmenting or scanning. I've read some people who defragment for a
whole night long daily or weekly and that of course causes a lot of wear
and tear...




There are more factors involved. Are all HHDs created equal? I think
not. Is that HDD powered all the time and subject to heat? How hot does
the inside of your computer actually get compared to others? Does that
HDD have a drive cooler or not? Was it ever subject to shock?

It's still to early to tell just how long an SSD will last as they are
still improving them. Are they improving HDDs?

I think an external HDD drive will last longer if it's dormant most of
the time.

I have almost 2 dozen SSDs and none have hailed. SSDs from a 50GB
Crucial to some 10 times that size. They might out live me. I'll post
back if they do.

In article , says...

Linea Recta wrote:
"Paul" schreef in bericht
...
mike wrote:
On 7/10/2014 11:56 AM, Wildman wrote:
On Thu, 10 Jul 2014 11:42:03 -0700, David E. Ross wrote:

I have a 100 GB solid-state drive with not quite 60 GB used. The
Windows defrag tool (dfrgui.exe) says it is 7% fragmented. Since
it is
solid-state, however, does defragmenting really mean anything?

The drive is Western Digital WD10EZEX-75ZF5A0.

The main purpose of defraging is to minimize hard drive
head seek time. Since the SSD does not have heads, there
is no benefit.


While I agree with the statement about not degfragging...

I researched SSD's a while back and decided not to implement one.
There were numerous articles about SSD's being fast at first,
but slowing dramatically with use. Don't remember the term, but
there was a process to restore the speed. Don't think it was
defragmenting as we know it, but it did rearrange stuff in the flash
and required periodic fixup.
Had something to do with the fact that data is written in blocks.
When you have something in every block, your only option is to read
the block, change it, write it all back. Not the same process as
mechanical seeking, but has similar symptoms.

Maybe someone can enlighten us.

TRIM is a feature which allows the OS to tell the
SSD drive, what sectors are no longer in usage. It
adds to the pool of free sectors that can be used
for data rearrangement.

The SSD drive itself, has one or two processors inside.
And firmware. The SSD works behind the scenes. In fact,
if you leave the computer running, the SSD can do write
operations to itself all night long. It you degraded the
SSD by doing a random 4KB write test ("hammered it"), a
good SSD will spend the whole night rearranging the blocks
to take up the least space. And leave as many whole free
blocks for tomorrow. By tomorrow, write performance will
be returned to the proper level again. Without such
behind-the-scenes maintenance, the write performance

Yea, I've had much poorer lasting time with Seagate drives over Western
Digital drives, some normally turned off and some on 24/7 don't matter.
That includes both internal and external drives. You can tell they
themselves have less confidence in them when warranty period has shrunk
to the low of only one year, used to be a time it was five years.

On 7/10/2014 10:14 PM, Paul wrote:
Also, research has shown, that "annealing" with heat, will repair
flash defects. The wearout phenomenon could be almost completely
removed, with annealing to fix defects. But so far, there is no
proposal on the table, as to how this knowledge can be applied in
practice.

I bought a used EeePC back in 2008 that the seller said that the machine
can't see the SSD. I bought it on assuming that the SSD was bad. When I
got it, I made sure the machine was useable by booting from an SD card
and all and the machine operated just fine. And yes, it looked like the
SSD was bad. But for some reason I left it on for about 90 minutes while
I was doing other things.

When I got back the BIOS could now see the SSD. I rebooted and it worked
just fine. Although let it cool back down again and it was dead again.
Warm it up for 90 minutes and it works again. I could have sent it in
under warrantee I suppose. Although I looked up the lot number of the
SSD and that lot was known for failures. So I found one online from
another lot and just replaced it and it had worked ever since.

A similar thing is known about LEDs, namely that the intensity drops
with time, and LEDs can be restored by baking. But perhaps at a
temperature that would ruin the plastic packaging.

We used to test LEDs by raising the voltage until they would fail. Some
would die right away. But some just got brighter and brighter and just
won't quit. And at this point, the lens would melt and they would keep
working.

I have a few LED spotlights. They only have one LED and I think it is
supposed to be 500,000 candle power or something. And all it has is a
surface mounted LED without a lens. If it were encased in plastic, it
would probably melt like those LEDs we were testing.

--
Bill
Gateway M465e ('06 era) - Kingston 120GB SSD - Thunderbird v24.4.0
Centrino Core2 Duo T7400 2.16 GHz - 4GB - Windows 8.1 Pro w/Media Center

On 7/11/2014 1:22 PM, Linea Recta wrote:
"Paul" schreef in bericht
...
SSD may be faster, but I believe that life span of an SSD is stil
less than that of a conventional hard disk? That's the main reason
for me not to touch SSD for the time being...

Well say you had a 120GB SSD. You would have to write 120GB worth to it
each day for the next 27 years to wear it out. I don't know about you,
but I can't even see myself averaging even 25GB per day. That means it
would be well over 100 years before it wears out.

I by the way have been using SSD since 2008 and I never had one fail on
me yet. I did purchase a machine that I figured the SSD had failed. It
turned out it was and from a known defective lot no less.

I think a modern SSD could beat my last batch of Seagate 500GB drives.
They were lasting a year.

You're joking? That's outrageous. And you had waranty I suppose?
Reading that I think I've been very lucky up till now with my drives.
They're all older than 10 years. But I never waste much time
defragmenting or scanning. I've read some people who defragment for a
whole night long daily or weekly and that of course causes a lot of wear
and tear...

Yeah I know people who defrag like that too. I just wait 2 or 3 years
and Windows says by then 60% fragmented or something. Then I record boot
times and application load times and then defrag and recheck the times.
And how depressing, I usually get about 1 to 2% boost in disk speed. Big
deal!

--
Bill
Gateway M465e ('06 era) - Kingston 120GB SSD - Thunderbird v24.4.0
Centrino Core2 Duo T7400 2.16 GHz - 4GB - Windows 8.1 Pro w/Media Center

On 7/10/2014 1:42 PM, David E. Ross wrote:
I have a 100 GB solid-state drive with not quite 60 GB used. The
Windows defrag tool (dfrgui.exe) says it is 7% fragmented. Since it is
solid-state, however, does defragmenting really mean anything?

The drive is Western Digital WD10EZEX-75ZF5A0.

I am so surprised that nobody had mentioned that Windows 7 and 8,
according to Microsoft, won't defrag a SSD even if you tried.

Hello, In Windows 7 - we turned off defrag for SSDs as you
mention in your entry; but in Windows 8, we have changed the
defrag tool to do a general optimization tool that handles
different kinds of storage, and in the case of SSD's it will
send 'trim' hints for the entire volume;

http://social.technet.microsoft.com/...ssds-a-default

Although I have found this true of Windows 8, but Windows 7 not. I ran
an administrator command prompt and ran defrag c: on two different
Windows 7 machines (both has SSD) and Windows didn't stop defrag from
defragging the SSDs.

--
Bill
Gateway M465e ('06 era) - Kingston 120GB SSD - Thunderbird v24.4.0
Centrino Core2 Duo T7400 2.16 GHz - 4GB - Windows 8.1 Pro w/Media Center

On 7/11/2014 4:03 PM, BillW50 wrote:
On 7/10/2014 1:42 PM, David E. Ross wrote:
I have a 100 GB solid-state drive with not quite 60 GB used. The
Windows defrag tool (dfrgui.exe) says it is 7% fragmented. Since it is
solid-state, however, does defragmenting really mean anything?

The drive is Western Digital WD10EZEX-75ZF5A0.

I am so surprised that nobody had mentioned that Windows 7 and 8,
according to Microsoft, won't defrag a SSD even if you tried.

Hello, In Windows 7 - we turned off defrag for SSDs as you
mention in your entry; but in Windows 8, we have changed the
defrag tool to do a general optimization tool that handles
different kinds of storage, and in the case of SSD's it will
send 'trim' hints for the entire volume;

http://social.technet.microsoft.com/...ssds-a-default


Although I have found this true of Windows 8, but Windows 7 not. I ran
an administrator command prompt and ran defrag c: on two different
Windows 7 machines (both has SSD) and Windows didn't stop defrag from
defragging the SSDs.

For Windows 8, I was using (Windows 7 doesn't have this switch):

defrag c: -o

If it is a hard drive, it will defrag. If it is a SSD, it invokes
retrim. Although issuing:

defrag c:

Under Windows 8, it will defrag a SSD. So why does it seem like
Microsoft rarely knows what they are talking about?

--
Bill
Gateway M465e ('06 era) - Kingston 120GB SSD - Thunderbird v24.4.0
Centrino Core2 Duo T7400 2.16 GHz - 4GB - Windows 8.1 Pro w/Media Center

On 7/11/2014 2:10 PM, pjp wrote:
Yea, I've had much poorer lasting time with Seagate drives over Western
Digital drives, some normally turned off and some on 24/7 don't matter.
That includes both internal and external drives. You can tell they
themselves have less confidence in them when warranty period has shrunk
to the low of only one year, used to be a time it was five years.

That has been my experience too. Although I noticed that some Seagates
are very good and some are pure junk.

--
Bill
Gateway M465e ('06 era) - Kingston 120GB SSD - Thunderbird v24.4.0
Centrino Core2 Duo T7400 2.16 GHz - 4GB - Windows 8.1 Pro w/Media Center

BillW50 wrote:


We used to test LEDs by raising the voltage until they would fail. Some
would die right away. But some just got brighter and brighter and just
won't quit. And at this point, the lens would melt and they would keep
working.

I have a few LED spotlights. They only have one LED and I think it is
supposed to be 500,000 candle power or something. And all it has is a
surface mounted LED without a lens. If it were encased in plastic, it
would probably melt like those LEDs we were testing.

The last record I saw for a single (high power) LED,
is someone testing the LEDs managed to put 17 amps
through one. The LED in that case, was soldered to
a copper slug, which functioned as a part of the heatsink.
At that current level, they're not quite as efficient as
they are at lower currents.

One limit on LEDs, is the bond wires. You can see the
bond wire that carries all the current, in this example.
Some of these LEDs have three bond wires. I don't know
how the LED was connected on the 17 amp one.

http://upload.wikimedia.org/wikipedi...C_Lumiled).jpg

And some LEDs are actually arrays, and are series connected
internally. You might need as much as 90V for the forward
voltage on those. You're not likely to find those in
a flashlight :-)

Paul

BillW50 wrote:
On 7/11/2014 4:03 PM, BillW50 wrote:
On 7/10/2014 1:42 PM, David E. Ross wrote:
I have a 100 GB solid-state drive with not quite 60 GB used. The
Windows defrag tool (dfrgui.exe) says it is 7% fragmented. Since it is
solid-state, however, does defragmenting really mean anything?

The drive is Western Digital WD10EZEX-75ZF5A0.

I am so surprised that nobody had mentioned that Windows 7 and 8,
according to Microsoft, won't defrag a SSD even if you tried.

Hello, In Windows 7 - we turned off defrag for SSDs as you
mention in your entry; but in Windows 8, we have changed the
defrag tool to do a general optimization tool that handles
different kinds of storage, and in the case of SSD's it will
send 'trim' hints for the entire volume;

http://social.technet.microsoft.com/...ssds-a-default



Although I have found this true of Windows 8, but Windows 7 not. I ran
an administrator command prompt and ran defrag c: on two different
Windows 7 machines (both has SSD) and Windows didn't stop defrag from
defragging the SSDs.

For Windows 8, I was using (Windows 7 doesn't have this switch):

defrag c: -o

If it is a hard drive, it will defrag. If it is a SSD, it invokes
retrim. Although issuing:

defrag c:

Under Windows 8, it will defrag a SSD. So why does it seem like
Microsoft rarely knows what they are talking about?


On Win8, maybe it depends on what your patch level is (8/8.1/8.1U1) ?

Paul

On 7/11/2014 5:29 PM, Paul wrote:
BillW50 wrote:

We used to test LEDs by raising the voltage until they would fail.
Some would die right away. But some just got brighter and brighter and
just won't quit. And at this point, the lens would melt and they would
keep working.

I have a few LED spotlights. They only have one LED and I think it is
supposed to be 500,000 candle power or something. And all it has is a
surface mounted LED without a lens. If it were encased in plastic, it
would probably melt like those LEDs we were testing.

The last record I saw for a single (high power) LED,
is someone testing the LEDs managed to put 17 amps
through one. The LED in that case, was soldered to
a copper slug, which functioned as a part of the heatsink.
At that current level, they're not quite as efficient as
they are at lower currents.

One limit on LEDs, is the bond wires. You can see the
bond wire that carries all the current, in this example.
Some of these LEDs have three bond wires. I don't know
how the LED was connected on the 17 amp one.

http://upload.wikimedia.org/wikipedi...C_Lumiled).jpg

Oh nice! :-)

And some LEDs are actually arrays, and are series connected
internally. You might need as much as 90V for the forward
voltage on those. You're not likely to find those in
a flashlight :-)

No these LED spot lights run from three C batteries (4.5v). On high it
will run for 25 hours and on low for 175 hours. So what are ratings for
alkaline C batteries, maybe 8000mAh? If so, high would be like 320ma and
low would be like 45ma.

--
Bill
Gateway M465e ('06 era) - Kingston 120GB SSD - Thunderbird v24.4.0
Centrino Core2 Duo T7400 2.16 GHz - 4GB - Windows 8.1 Pro w/Media Center

On 7/11/2014 5:31 PM, Paul wrote:
BillW50 wrote:
On 7/11/2014 4:03 PM, BillW50 wrote:
On 7/10/2014 1:42 PM, David E. Ross wrote:
I have a 100 GB solid-state drive with not quite 60 GB used. The
Windows defrag tool (dfrgui.exe) says it is 7% fragmented. Since it is
solid-state, however, does defragmenting really mean anything?

The drive is Western Digital WD10EZEX-75ZF5A0.

I am so surprised that nobody had mentioned that Windows 7 and 8,
according to Microsoft, won't defrag a SSD even if you tried.

Hello, In Windows 7 - we turned off defrag for SSDs as you
mention in your entry; but in Windows 8, we have changed the
defrag tool to do a general optimization tool that handles
different kinds of storage, and in the case of SSD's it will
send 'trim' hints for the entire volume;

http://social.technet.microsoft.com/...ssds-a-default



Although I have found this true of Windows 8, but Windows 7 not. I ran
an administrator command prompt and ran defrag c: on two different
Windows 7 machines (both has SSD) and Windows didn't stop defrag from
defragging the SSDs.

For Windows 8, I was using (Windows 7 doesn't have this switch):

defrag c: -o

If it is a hard drive, it will defrag. If it is a SSD, it invokes
retrim. Although issuing:

defrag c:

Under Windows 8, it will defrag a SSD. So why does it seem like
Microsoft rarely knows what they are talking about?

On Win8, maybe it depends on what your patch level is (8/8.1/8.1U1) ?

Fair enough, the above was done on 8.1.U1. I just fired up 8.0 and it
works exactly the same.

--
Bill
Gateway M465e ('06 era) - Kingston 120GB SSD - Thunderbird v24.4.0
Centrino Core2 Duo T7400 2.16 GHz - 4GB - Windows 8.1 Pro w/Media Center

BillW50 wrote:
On 7/11/2014 5:29 PM, Paul wrote:
BillW50 wrote:

We used to test LEDs by raising the voltage until they would fail.
Some would die right away. But some just got brighter and brighter and
just won't quit. And at this point, the lens would melt and they would
keep working.

I have a few LED spotlights. They only have one LED and I think it is
supposed to be 500,000 candle power or something. And all it has is a
surface mounted LED without a lens. If it were encased in plastic, it
would probably melt like those LEDs we were testing.

The last record I saw for a single (high power) LED,
is someone testing the LEDs managed to put 17 amps
through one. The LED in that case, was soldered to
a copper slug, which functioned as a part of the heatsink.
At that current level, they're not quite as efficient as
they are at lower currents.

One limit on LEDs, is the bond wires. You can see the
bond wire that carries all the current, in this example.
Some of these LEDs have three bond wires. I don't know
how the LED was connected on the 17 amp one.

http://upload.wikimedia.org/wikipedi...C_Lumiled).jpg


Oh nice! :-)

And some LEDs are actually arrays, and are series connected
internally. You might need as much as 90V for the forward
voltage on those. You're not likely to find those in
a flashlight :-)

No these LED spot lights run from three C batteries (4.5v). On high it
will run for 25 hours and on low for 175 hours. So what are ratings for
alkaline C batteries, maybe 8000mAh? If so, high would be like 320ma and
low would be like 45ma.


350mA happens to be a common value for some of these LEDs.

To work well, the LED needs to be able to dump the heat. And
this is a limitation of a lot of flashlights.

My home-made bicycle light, is open on the sides for airflow.
I was driving the bicycle in the rain and dark one day,
and the water on the PCB actually started to conduct so
much, it reduced the light output to almost nothing.
As a consequence, I built a housing around the LED array
on four sides, leaving the two side surfaces open for airflow.

I have a LED flashlight, where there is no place for the
heat to go. And that's not the best thing for the LED.
Some LEDs now, use silicon carbide for a substrate, which
is supposed to take more heat. But if you insulate the
LED well (airtight flashlight), you're likely to exceed
the operating temperature for any practical LED composition.
That's not a problem for the old incandescent bulbs.

This is an example of a heatsink for high power LED home projects.
It uses two bolts to hold the Star in place, but if you
actually build one of these, the bolts don't really hold
things as securely as you might hope. If you put some
permanent thermal epoxy under the Star, that thing will
stay on there... forever.

http://www.led-heatsink.com/upload/i...g_family.j pg

Paul

On 7/11/2014 6:05 PM, Paul wrote:
BillW50 wrote:
On 7/11/2014 5:29 PM, Paul wrote:
BillW50 wrote:

We used to test LEDs by raising the voltage until they would fail.
Some would die right away. But some just got brighter and brighter and
just won't quit. And at this point, the lens would melt and they would
keep working.

I have a few LED spotlights. They only have one LED and I think it is
supposed to be 500,000 candle power or something. And all it has is a
surface mounted LED without a lens. If it were encased in plastic, it
would probably melt like those LEDs we were testing.

The last record I saw for a single (high power) LED,
is someone testing the LEDs managed to put 17 amps
through one. The LED in that case, was soldered to
a copper slug, which functioned as a part of the heatsink.
At that current level, they're not quite as efficient as
they are at lower currents.

One limit on LEDs, is the bond wires. You can see the
bond wire that carries all the current, in this example.
Some of these LEDs have three bond wires. I don't know
how the LED was connected on the 17 amp one.

http://upload.wikimedia.org/wikipedi...C_Lumiled).jpg


Oh nice! :-)

And some LEDs are actually arrays, and are series connected
internally. You might need as much as 90V for the forward
voltage on those. You're not likely to find those in
a flashlight :-)

No these LED spot lights run from three C batteries (4.5v). On high it
will run for 25 hours and on low for 175 hours. So what are ratings
for alkaline C batteries, maybe 8000mAh? If so, high would be like
320ma and low would be like 45ma.


350mA happens to be a common value for some of these LEDs.

To work well, the LED needs to be able to dump the heat. And
this is a limitation of a lot of flashlights.

My home-made bicycle light, is open on the sides for airflow.
I was driving the bicycle in the rain and dark one day,
and the water on the PCB actually started to conduct so
much, it reduced the light output to almost nothing.
As a consequence, I built a housing around the LED array
on four sides, leaving the two side surfaces open for airflow.

I have a LED flashlight, where there is no place for the
heat to go. And that's not the best thing for the LED.
Some LEDs now, use silicon carbide for a substrate, which
is supposed to take more heat. But if you insulate the
LED well (airtight flashlight), you're likely to exceed
the operating temperature for any practical LED composition.
That's not a problem for the old incandescent bulbs.

This is an example of a heatsink for high power LED home projects.
It uses two bolts to hold the Star in place, but if you
actually build one of these, the bolts don't really hold
things as securely as you might hope. If you put some
permanent thermal epoxy under the Star, that thing will
stay on there... forever.

http://www.led-heatsink.com/upload/i...g_family.j pg

Oh good stuff. I haven't seen the heat problem yet. That LED spot light
is this one by the way. They sell for $19.95 or less every black Friday.
Oh they are only 155 lumen output. I thought they were much more.

http://www.amazon.com/C-Crane-CC-Spo...VXE/ref=sr_1_2

I suppose those LEDs that are used for incandescent replacements for
home lighting are arranged in an arrays. The ones I use through most of
the house, only the heatsink gets hot. Like 190 degrees F from my IR
probe. Some say you shouldn't use them in an air tight fixture. But I
use one outside in one and it has been working just fine. Although it
could be the first one to go as far as I know.

--
Bill
Gateway M465e ('06 era) - Kingston 120GB SSD - Thunderbird v24.4.0
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