Replacing electrolytics - any disadvantages of high temp ones?
I'm sure many of you with old equipment must have considered the fact that
electrolytic caps have a finite life and considered replacing them. I have a few
that look suspect (bulging) on a transceiver, and decided to replace them. I'm
tempted to do all of them in the PSU, as:
- It runs hot
- PSU could destory other bits
- Two of the 15 or so caps on the PSU board show signs of bulging.
For the PSU I used all 105 deg C caps, apart from one which was rated at 125 deg
C. These are higher spec than the originals.
I also replaced another cap (not in a hot region) with a 105 deg C rated cap.
I've made my capacitor choice based on assuming.
-
Higher temperature devices (like 105 deg C) will be more relieable than low
temperature ones like the standard 85 deg C cap. I'm sure at high temperatures,
that must be true, but I've no idea if it would be beneficial if the cap does
not get very warm. -
There are no disadvantage of the higher temperature caps, other than cost.
Are these true?
I've ruled out the idea of replacing all electrolytics with new ones. That would
be a LOT of work, and cost a lot of money.
Dave
--
A: Because it messes up the order in which people normally read text.
Q: Why is top-posting such a bad thing?
A: Top-posting.
Q: What is the most annoying thing in e-mail?
In message 4DFFBAF4.4070004@onetel.net, "Dr. David Kirkby" writes:
- Higher temperature devices (like 105 deg C) will be more relieable than low
temperature ones like the standard 85 deg C cap. I'm sure at high temperatures,
You should check both temperature and lifetime rating of the capactors.
There are many capacitors on the market these days with 5000h or
even 2000h rated life.
That is 7 or 3 months respectively.
And yes, it should be criminal to manufacture and sell those.
--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG | TCP/IP since RFC 956
FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
On 06/20/11 10:44 PM, Poul-Henning Kamp wrote:
In message4DFFBAF4.4070004@onetel.net, "Dr. David Kirkby" writes:
- Higher temperature devices (like 105 deg C) will be more relieable than low
temperature ones like the standard 85 deg C cap. I'm sure at high temperatures,
You should check both temperature and lifetime rating of the capactors.
I have, but I would assume one rated at 6000 hours at 125 deg C would be at
least as good as one rated at 7000 hours at 105 deg C.
There are many capacitors on the market these days with 5000h or
even 2000h rated life.
That is 7 or 3 months respectively.
Even 1000 hours I've seen. But these are of course at the maximum temperature,
which few would use them at. Otherwise failure rates would be a lot higher than
they are.
I've not seen any electrolytics rated more than 10,000 hours (14 months), but
they last a lot longer if the temperature is lower.
My PC is already more than 14 months old, and has been on 24/7. Hopefully it is
not dying on me.
And yes, it should be criminal to manufacture and sell those.
Well, I think the MTBF will be a lot more than that in practical use, as few
would design equipment to run at 85 deg C, which is the lowest maximum
temperature rating I've seen on any cap.
--
A: Because it messes up the order in which people normally read text.
Q: Why is top-posting such a bad thing?
A: Top-posting.
Q: What is the most annoying thing in e-mail?
David Another important factor when considering power supply caps is ripple
current rating. It is generally the ripple current that makes them get warm.
I think the "usual" thumbnail calculation still work for caps if you can
reduce the temperature by 20 degrees they will last at least 4 times as
long. That is an activation energy (Arrhenius eqn) of about 1ev. I also
believe though I cant quote that they are best run at about 75% of their
specified working voltage. I have always wonderd about this but it would
seem to be a mistake to have too low a voltage on electrolytics ...maybe
something to do with the strength of the instulating layer formed.
Alan
G3NYK
----- Original Message -----
From: "Dr. David Kirkby" david.kirkby@onetel.net
To: "Discussion of precise time and frequency measurement"
time-nuts@febo.com
Sent: Tuesday, June 21, 2011 12:40 AM
Subject: Re: [time-nuts] Replacing electrolytics - any disadvantages of high
temp ones?
On 06/20/11 10:44 PM, Poul-Henning Kamp wrote:
In message4DFFBAF4.4070004@onetel.net, "Dr. David Kirkby" writes:
- Higher temperature devices (like 105 deg C) will be more relieable
than low
temperature ones like the standard 85 deg C cap. I'm sure at high
temperatures,
You should check both temperature and lifetime rating of the capactors.
I have, but I would assume one rated at 6000 hours at 125 deg C would be
at
least as good as one rated at 7000 hours at 105 deg C.
There are many capacitors on the market these days with 5000h or
even 2000h rated life.
That is 7 or 3 months respectively.
Even 1000 hours I've seen. But these are of course at the maximum
temperature,
which few would use them at. Otherwise failure rates would be a lot higher
than
they are.
I've not seen any electrolytics rated more than 10,000 hours (14 months),
but
they last a lot longer if the temperature is lower.
My PC is already more than 14 months old, and has been on 24/7. Hopefully
it is
not dying on me.
And yes, it should be criminal to manufacture and sell those.
Well, I think the MTBF will be a lot more than that in practical use, as
few
would design equipment to run at 85 deg C, which is the lowest maximum
temperature rating I've seen on any cap.
--
A: Because it messes up the order in which people normally read text.
Q: Why is top-posting such a bad thing?
A: Top-posting.
Q: What is the most annoying thing in e-mail?
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and follow the instructions there.
On 06/21/11 12:59 AM, Alan Melia wrote:
David Another important factor when considering power supply caps is ripple
current rating. It is generally the ripple current that makes them get warm.
Yes. I must admit I did not give that any thought, which was rather stupid of
me. But I did not buy cheap caps. I will check the ripple ratings, but its hard
to know exactly what is needed.
I think the "usual" thumbnail calculation still work for caps if you can
reduce the temperature by 20 degrees they will last at least 4 times as
long. That is an activation energy (Arrhenius eqn) of about 1ev. I also
believe though I cant quote that they are best run at about 75% of their
specified working voltage. I have always wonderd about this but it would
seem to be a mistake to have too low a voltage on electrolytics ...maybe
something to do with the strength of the instulating layer formed.
Yes, I have heard this before about not using them at too low a voltage. I don't
know whether its an old-wives tale, or if there is any truth to it.
Alan
G3NYK
Thanks for your comments Alan,
Dave G8WRB.
Dr. David Kirkby wrote:
I think the "usual" thumbnail calculation still work for caps if you can
reduce the temperature by 20 degrees they will last at least 4 times as
long. That is an activation energy (Arrhenius eqn) of about 1ev. I also
believe though I cant quote that they are best run at about 75% of their
specified working voltage. I have always wonderd about this but it would
seem to be a mistake to have too low a voltage on electrolytics ...maybe
something to do with the strength of the instulating layer formed.
Yes, I have heard this before about not using them at too low a voltage.
I don't know whether its an old-wives tale, or if there is any truth to it.
It is discussed in ITT's Reference Data for Radio Engineers. It certainly
was true at one time.... not necessarily anymore, though. In the old days,
the oxide layer that formed the dielectric was mostly formed in place by
applying a controlled current to the capacitor at a voltage above the intended
operating voltage. Now, the aluminum electrode foil is anodized before the
capacitor is assembled, and the electrolytes are specifically formulated to
not damage the oxide layer.... and yet, I find that some electrolytic
capacitors that have been run at lower than normal voltage improve markedly
when "reformed" by applying rated voltage through a 10K resistor for a
couple of hours.
-Chuck Harris
In message 4E008A73.50701@erols.com, Chuck Harris writes:
and yet, I find that some electrolytic
capacitors that have been run at lower than normal voltage improve markedly
when "reformed" by applying rated voltage through a 10K resistor for a
couple of hours.
I noticed in a datasheet at one point, that the capacity only was
warranted above a certain percentage of rated voltage. No explanation
was given.
--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG | TCP/IP since RFC 956
FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
Group,
During my days of interest in antique radios, I learned that
the dielectric between aluminum plates was formed by passing
current in one direction to build up an oxide coating on the
plates, which became the dielectric. The thickness is directly
proportional to working voltage and inversely proportional to
capacitance. As we learned from reforming old caps, the oxide
thins when there is no voltage on the cap, but can be restored
by passing several milliamps through the cap. Applying rated
voltage before it was formed would destroy the cap by welding
spots of the plates together.
I'm not sure that this applies to modern caps.
As to the temperature rating, a high temp cap run in a cool
environment will be as unhappy as someone transplanted from
Miami to Minneapolis in the winter. It may work, but it will
be very unhappy - so it depends on your empathy for the cap.
There ought to be a way to work precision time into this
thread, but I can't think of one.
Bill Hawkins
-----Original Message-----
From: Poul-Henning Kamp
Sent: Tuesday, June 21, 2011 2:40 PM
In message 4E008A73.50701@erols.com, Chuck Harris writes:
and yet, I find that some electrolytic
capacitors that have been run at lower than normal voltage improve markedly
when "reformed" by applying rated voltage through a 10K resistor for a
couple of hours.
I noticed in a datasheet at one point, that the capacity only was
warranted above a certain percentage of rated voltage. No explanation
was given.
Hi Bill,
I agree with your forming information, as applied to older caps,
but not your temperature information. The 105C high temp caps
are just as happy, or unhappy really, with low temperatures as
the 85C caps. Basically the difference between the two is water.
The 85C caps have an electrolyte with a significant amount of water,
that boils dry at high temperatures. The 105C caps don't. Kind
of like the difference between an antifreeze and water solution,
and straight antifreeze. Both seriously run out of capacitance
when they get below freezing.
The loss of capacitance can really bite you when you use integrated
low overhead voltage regulators in automotive temperature ranges.
The regulators will oscillate if they don't have enough capacitance
on their input terminals... which can happen if you specify an
electrolytic capacitor that is right around the 100uf needed. When
it gets to 0C, and becomes a 10uf capacitor, the regulator takes off
and burns up your load.
-Chuck Harris
Bill Hawkins wrote:
Group,
During my days of interest in antique radios, I learned that
the dielectric between aluminum plates was formed by passing
current in one direction to build up an oxide coating on the
plates, which became the dielectric. The thickness is directly
proportional to working voltage and inversely proportional to
capacitance. As we learned from reforming old caps, the oxide
thins when there is no voltage on the cap, but can be restored
by passing several milliamps through the cap. Applying rated
voltage before it was formed would destroy the cap by welding
spots of the plates together.
I'm not sure that this applies to modern caps.
As to the temperature rating, a high temp cap run in a cool
environment will be as unhappy as someone transplanted from
Miami to Minneapolis in the winter. It may work, but it will
be very unhappy - so it depends on your empathy for the cap.
There ought to be a way to work precision time into this
thread, but I can't think of one.
Bill Hawkins
-----Original Message-----
From: Poul-Henning Kamp
Sent: Tuesday, June 21, 2011 2:40 PM
In message4E008A73.50701@erols.com, Chuck Harris writes:
and yet, I find that some electrolytic
capacitors that have been run at lower than normal voltage improve markedly
when "reformed" by applying rated voltage through a 10K resistor for a
couple of hours.
I noticed in a datasheet at one point, that the capacity only was
warranted above a certain percentage of rated voltage. No explanation
was given.
time-nuts mailing list -- time-nuts@febo.com
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and follow the instructions there.
Oh to add further information.
I love old caps. They go bad and I get my test equipment for cheap.
That said I do measure the caps I am going to put in on a old style HP cap
meter that can apply up to 100 volts to the cap. I look for leakage. What I
see in quite modern caps that have been around for a while (Surplus you get
at hamfest approx 3-5 years) is that there is a higher leakage current that
does settle down after a while. So I sense the forming effect still exists.
Am I wrong about this??
Regard
Paul
WB8TSL
On Wed, Jun 22, 2011 at 1:16 AM, Chuck Harris cfharris@erols.com wrote:
Hi Bill,
I agree with your forming information, as applied to older caps,
but not your temperature information. The 105C high temp caps
are just as happy, or unhappy really, with low temperatures as
the 85C caps. Basically the difference between the two is water.
The 85C caps have an electrolyte with a significant amount of water,
that boils dry at high temperatures. The 105C caps don't. Kind
of like the difference between an antifreeze and water solution,
and straight antifreeze. Both seriously run out of capacitance
when they get below freezing.
The loss of capacitance can really bite you when you use integrated
low overhead voltage regulators in automotive temperature ranges.
The regulators will oscillate if they don't have enough capacitance
on their input terminals... which can happen if you specify an
electrolytic capacitor that is right around the 100uf needed. When
it gets to 0C, and becomes a 10uf capacitor, the regulator takes off
and burns up your load.
-Chuck Harris
Bill Hawkins wrote:
Group,
During my days of interest in antique radios, I learned that
the dielectric between aluminum plates was formed by passing
current in one direction to build up an oxide coating on the
plates, which became the dielectric. The thickness is directly
proportional to working voltage and inversely proportional to
capacitance. As we learned from reforming old caps, the oxide
thins when there is no voltage on the cap, but can be restored
by passing several milliamps through the cap. Applying rated
voltage before it was formed would destroy the cap by welding
spots of the plates together.
I'm not sure that this applies to modern caps.
As to the temperature rating, a high temp cap run in a cool
environment will be as unhappy as someone transplanted from
Miami to Minneapolis in the winter. It may work, but it will
be very unhappy - so it depends on your empathy for the cap.
There ought to be a way to work precision time into this
thread, but I can't think of one.
Bill Hawkins
-----Original Message-----
From: Poul-Henning Kamp
Sent: Tuesday, June 21, 2011 2:40 PM
In message<4E008A73.50701@erols.**com 4E008A73.50701@erols.com>, Chuck
Harris writes:
and yet, I find that some electrolytic
capacitors that have been run at lower than normal voltage improve
markedly
when "reformed" by applying rated voltage through a 10K resistor for a
couple of hours.
I noticed in a datasheet at one point, that the capacity only was
warranted above a certain percentage of rated voltage. No explanation
was given.
_____________**
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IMO, the issue of reforming is very much alive with electrolytics, old and
new.
In some modern PZT actuator drivers, there is a warning to bring up the
supplies slowly if the unit has been dormant for sx months or more.
-John
================
Oh to add further information.
I love old caps. They go bad and I get my test equipment for cheap.
That said I do measure the caps I am going to put in on a old style HP cap
meter that can apply up to 100 volts to the cap. I look for leakage. What
I
see in quite modern caps that have been around for a while (Surplus you
get
at hamfest approx 3-5 years) is that there is a higher leakage current
that
does settle down after a while. So I sense the forming effect still
exists.
Am I wrong about this??
Regard
Paul
WB8TSL
On Wed, Jun 22, 2011 at 1:16 AM, Chuck Harris cfharris@erols.com wrote:
Hi Bill,
I agree with your forming information, as applied to older caps,
but not your temperature information. The 105C high temp caps
are just as happy, or unhappy really, with low temperatures as
the 85C caps. Basically the difference between the two is water.
The 85C caps have an electrolyte with a significant amount of water,
that boils dry at high temperatures. The 105C caps don't. Kind
of like the difference between an antifreeze and water solution,
and straight antifreeze. Both seriously run out of capacitance
when they get below freezing.
The loss of capacitance can really bite you when you use integrated
low overhead voltage regulators in automotive temperature ranges.
The regulators will oscillate if they don't have enough capacitance
on their input terminals... which can happen if you specify an
electrolytic capacitor that is right around the 100uf needed. When
it gets to 0C, and becomes a 10uf capacitor, the regulator takes off
and burns up your load.
-Chuck Harris
Bill Hawkins wrote:
Group,
During my days of interest in antique radios, I learned that
the dielectric between aluminum plates was formed by passing
current in one direction to build up an oxide coating on the
plates, which became the dielectric. The thickness is directly
proportional to working voltage and inversely proportional to
capacitance. As we learned from reforming old caps, the oxide
thins when there is no voltage on the cap, but can be restored
by passing several milliamps through the cap. Applying rated
voltage before it was formed would destroy the cap by welding
spots of the plates together.
I'm not sure that this applies to modern caps.
As to the temperature rating, a high temp cap run in a cool
environment will be as unhappy as someone transplanted from
Miami to Minneapolis in the winter. It may work, but it will
be very unhappy - so it depends on your empathy for the cap.
There ought to be a way to work precision time into this
thread, but I can't think of one.
Bill Hawkins
-----Original Message-----
From: Poul-Henning Kamp
Sent: Tuesday, June 21, 2011 2:40 PM
In message<4E008A73.50701@erols.**com 4E008A73.50701@erols.com>,
Chuck
Harris writes:
and yet, I find that some electrolytic
capacitors that have been run at lower than normal voltage improve
markedly
when "reformed" by applying rated voltage through a 10K resistor for
a
couple of hours.
I noticed in a datasheet at one point, that the capacity only was
warranted above a certain percentage of rated voltage. No explanation
was given.
_____________**
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To unsubscribe, go to https://www.febo.com/cgi-bin/**
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A very good reference for aluminum electrolytic use:
http://www.cde.com/catalogs/AEappGUIDE.pdf
Guides for other capacitor types are also on this page:
http://www.cde.com/appguide/
Had not seen these links and at least so far the CDE sights quite good
Thanks
On Wed, Jun 22, 2011 at 12:35 PM, Robert LaJeunesse <
rlajeunesse@sbcglobal.net> wrote:
A very good reference for aluminum electrolytic use:
http://www.cde.com/catalogs/AEappGUIDE.pdf
Guides for other capacitor types are also on this page:
http://www.cde.com/appguide/
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and follow the instructions there.
On 06/21/11 08:39 PM, Poul-Henning Kamp wrote:
In message4E008A73.50701@erols.com, Chuck Harris writes:
and yet, I find that some electrolytic
capacitors that have been run at lower than normal voltage improve markedly
when "reformed" by applying rated voltage through a 10K resistor for a
couple of hours.
I noticed in a datasheet at one point, that the capacity only was
warranted above a certain percentage of rated voltage. No explanation
was given.
Note on the link posted by Robert LaJeunesse:
http://www.cde.com/catalogs/AEappGUIDE.pdf
it says voltage derating gives better reliability:
---=====
"Aluminum electrolytic capacitors made with formation voltages
at least 35% higher than rated voltage and with rated tempera-
tures of 85 oC or higher, don’t require much voltage derating. In
applications operating at less than 45 oC no derating is needed,
and with up to 75 oC, 10% is sufficient. For higher temperatures
and with high ripple current, 15% or 20% is appropriate. Since
operating life continues to increase for further derating, military
and space applications use 50% voltage derating."
---=======
I've herd stories one should not operating caps well below their rated voltage,
but that would tend to suggest that is not so.
--
A: Because it messes up the order in which people normally read text.
Q: Why is top-posting such a bad thing?
A: Top-posting.
Q: What is the most annoying thing in e-mail?
Sorry to perpetuate the OT discussion, but there is an excellent series of articles by capacitor design engineer Cyril Bateman called Understanding Capacitors, published in EW&WW magazine in the late '90s. The article on electrolytics covers almost anything you might want to know about them, and is a very worthwhile read. I highly recommend the whole series.
Cyril had the articles posted on his own website some time ago, which I can no longer find. But, they are still available online if you search around.
- Chad.
On Jun 23, 2011, at 9:10, "Dr. David Kirkby" david.kirkby@onetel.net wrote:
On 06/21/11 08:39 PM, Poul-Henning Kamp wrote:
In message4E008A73.50701@erols.com, Chuck Harris writes:
and yet, I find that some electrolytic
capacitors that have been run at lower than normal voltage improve markedly
when "reformed" by applying rated voltage through a 10K resistor for a
couple of hours.
I noticed in a datasheet at one point, that the capacity only was
warranted above a certain percentage of rated voltage. No explanation
was given.
Note on the link posted by Robert LaJeunesse:
http://www.cde.com/catalogs/AEappGUIDE.pdf
it says voltage derating gives better reliability:
---=====
"Aluminum electrolytic capacitors made with formation voltages
at least 35% higher than rated voltage and with rated tempera-
tures of 85 oC or higher, don’t require much voltage derating. In
applications operating at less than 45 oC no derating is needed,
and with up to 75 oC, 10% is sufficient. For higher temperatures
and with high ripple current, 15% or 20% is appropriate. Since
operating life continues to increase for further derating, military
and space applications use 50% voltage derating."
---=======
I've herd stories one should not operating caps well below their rated voltage, but that would tend to suggest that is not so.
--
A: Because it messes up the order in which people normally read text.
Q: Why is top-posting such a bad thing?
A: Top-posting.
Q: What is the most annoying thing in e-mail?
time-nuts mailing list -- time-nuts@febo.com
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and follow the instructions there.
Hi Chad:
Google found it:
http://techdoc.kvindesland.no/radio/passivecomp/20061223155312558.pdf
But it's not that informative.
The best info I've seen on measuring components is the HP (Agilent)
Impedance Handbook.
http://cp.literature.agilent.com/litweb/pdf/5950-3000.pdf
I measured dozens of caps using a number of different methods to see how
well the combined ESR and Capacitance meter I sell works.
http://www.prc68.com/I/ESRmicro.shtml
http://www.prc68.com/I/Capacitors.shtml
Does anyone know of a modern cap leakage tester?
Have Fun,
Brooke Clarke
http://www.PRC68.com
GMail / AnalogAficionado wrote:
Cyril Bateman called Understanding Capacitors
Sencor LC 102.
-John
==================
[snip]
Hi Brooke that is only the last of about 5 or 6 articles in the same journal
you need to find the others as well. Cyril used to work for one of the big
UK manufacturers I believe. I think I still have the paper copies of E&WW
somewhere.
Alan
G3NYK
----- Original Message -----
From: "Brooke Clarke" brooke@pacific.net
To: "Discussion of precise time and frequency measurement"
time-nuts@febo.com
Sent: Friday, June 24, 2011 7:22 PM
Subject: Re: [time-nuts] Replacing electrolytics - any disadvantages of high
temp ones?
Hi Chad:
Google found it:
http://techdoc.kvindesland.no/radio/passivecomp/20061223155312558.pdf
But it's not that informative.
The best info I've seen on measuring components is the HP (Agilent)
Impedance Handbook.
http://cp.literature.agilent.com/litweb/pdf/5950-3000.pdf
I measured dozens of caps using a number of different methods to see how
well the combined ESR and Capacitance meter I sell works.
http://www.prc68.com/I/ESRmicro.shtml
http://www.prc68.com/I/Capacitors.shtml
Does anyone know of a modern cap leakage tester?
Have Fun,
Brooke Clarke
http://www.PRC68.com
GMail / AnalogAficionado wrote:
Cyril Bateman called Understanding Capacitors
time-nuts mailing list -- time-nuts@febo.com
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and follow the instructions there.
Hi John:
It's almost $1k and does much more than measure leakage. Is there a
much lower cost instrument that's aimed at just leakage?
Have Fun,
Brooke Clarke
http://www.PRC68.com
J. Forster wrote:
Sencor LC 102
Hi again John:
The manual for the LC 102 is free from BAMA and it's got all kinds of
useful info.
http://bama.edebris.com/manuals/sencore/lc102/
Have Fun,
Brooke Clarke
http://www.PRC68.com
Brooke Clarke wrote:
Hi John:
It's almost $1k and does much more than measure leakage. Is there a
much lower cost instrument that's aimed at just leakage?
Have Fun,
Brooke Clarke
http://www.PRC68.com
J. Forster wrote:
Sencor LC 102
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