Please share with me your experience in building Data-Logger

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I want to build a data-logger that records temperature and pressure every second for 20 hours. My circuit must work in a range of 20-130 'C and 0 - 9000 PSI ! And it must be inside a cylindrical chamber with a diameter of 25mm and a length of 45cm.

This circuit goes deep into the Earth to a depth of 500 meters, through an oil tube. so I must put batteries in the chamber.

 

  • What are the points that I must consider? (Everything! Such as regulators for PIC, Type of batteries, Type of Memories? SD Flash?EEPROM? ... , Protecting the circuit of electromagnetic noises, ans so on)
  • Which PIC is the best for this purpose? PIC16? PIC18? Atme Which model?
  • I must bought Extended Elements or I can use thermal insulation and use the same Industrial elements?
  • Which PIC compiler is the best for Starting PIC with this project?(If PIC is the best)
  • What kind of sensors do you offer? Analog? Digital? and which one? (Name)
  • Am I need a special PCB or it can be like other normal PCBs?
  • Should I consider to design a reset circuit for Brown Out pin? If so, Why? and How?
     

I don't want you to answer all the questions. Please answer whatever you want (of above questions.) If the question is very terrible for this site,please leave a comment,and I will remove it after 1 week :) I appreciate any any similar experience in building this kind of circuit.I am really a brand of new in this kind of projects. please help me to build this circuit.

Is there any PIC forum like this forum?

Last Edited: Thu. Dec 18, 2014 - 09:18 AM
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If you're just asking about the general electronics principles & issues, then this should be in the General Electronics forum - the clue is in the name!

 

If you're asking specifically about PICs, then AVR Freaks is obviously the wrong site all together - again, the clue is in the name!

 

Try: http://www.microchip.com/forums/

 

 

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There is no one best PIC or AVR. And  neither has any overwhelming advantage over the other. Use the one you are comfortable with. Choose one that has the features you need.

 

If it is in a metal housing, you won't need to worry about EMI UNLESS there is a com link to the outside world.

 

130C is pretty high for ICs generally,. I would look at automotive grade. These generally have a higher high temperature limit. Insulation won't help you because it will reach the local ambient temperature in less than 20 hours, even with insulation.

 

20 hours, 1 sample per second makes 72,000 samples. At 16 bits per value (4 bytes per sample), you will need at least 288,000 bytes. I would use one of the serial NV ram chips; I don't think that you will easily find SD or microSD chips that will be spec'd to that high a temperature.  One of your challenges will be how to read out the data. You will probably want a crystal clock so that your sample rate is highly predicable and you won't have to include a time stamp (which takes memory).

 

The PCB can probably be normal, though it will be near the upper limit for FR4 or modern equivalents.

 

You don't need an external reset/watchdog. AVRs have internal brownout and watchdog functions internally.

 

I can't recommend any specific sensors. It will depend on the temperature and pressure accuracy that you need, and your power availability. For the pressure sensor, it will be critical how you transmit the pressure from the outside surface of the enclosure into the sensor. That will have a major impact on your  sensor choice. Probably one of those in a metal housing and an integral port tube that is part of the sensor housing.

 

I have some experience with data loggers, under water and in the general environment but not that high temperature nor pressure. Max depth I worked with was about 100 meters. You have some major challenges, ahead.

 

Jim

 

Until Black Lives Matter, we do not have "All Lives Matter"!

 

 

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moved to general electronics

I would rather attempt something great and fail, than attempt nothing and succeed - Fortune Cookie

 

"The critical shortage here is not stuff, but time." - Johan Ekdahl

 

"Step N is required before you can do step N+1!" - ka7ehk

 

"If you want a career with a known path - become an undertaker. Dead people don't sue!" - Kartman

"Why is there a "Highway to Hell" and only a "Stairway to Heaven"? A prediction of the expected traffic load?"  - Lee "theusch"

 

Speak sweetly. It makes your words easier to digest when at a later date you have to eat them ;-)  - Source Unknown

Please Read: Code-of-Conduct

Atmel Studio6.2/AS7, DipTrace, Quartus, MPLAB, RSLogix user

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Sounds like a question tailor-made for Neil.

 

Ross McKenzie ValuSoft Melbourne Australia

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you need to hire someone to do the design, fabrication and reliability testing.

This is not a beginners project.

I work at a company that builds custom hardware like this. I know a lot about this stuff, and there is no way I would develop a commercial device of that scale on my own. It's way more complex than you think.

 

Just imagine how much it would cost if it fails in the hole and how it would make you look.

Dropping a sensor 500 meters can't be cheap

Keith Vasilakes

Firmware engineer

Minnesota

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To add to my comments, above -

 

Your housing needs to be a pressure housing. Batteries, of any kind, will NOT survive 9000 PSI. Period.

 

As a result of this, a significant part of your design is going to be mechanical. 

 

Likewise, the port that your pressure sensor uses to sense the outside pressure. That is going to be an opening in the pressure housing, The tube, or what ever it is, that conveys the pressure from the exterior of the housing to the sensor, will need to be able to withstand a pressure differential of 9000 PSI. Also, the joint between that tube and the pressure housing. All that is no small task.

 

Whether sensors are analog or digital is of no importance. Any micro can handle either. Choose what handles your max pressure and has the accuracy at the power consumption you can tolerate. 

 

Jim

 

Until Black Lives Matter, we do not have "All Lives Matter"!

 

 

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Strain gauges glued to the outside of gun barrels can measure the internal pressure without any penetration, so I expect an internal strain gauge could record external pressure. Search for such devices.

 

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May I ask you please share all the points that I must consider? It is late to discard. I must do it!
Any point you know please teach me. 

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You've decided to undertake a very complex project. To expect us to solve it for you is putting your expectations way too high.

Temperature is going to be a problem. Insulation can only do so much and the time involved means your electronics are going to get roasted. Batteries would be a major problem methinks. Best be Googling and finding out what you can.

TI have a range of high temperature microcontrollers.

Worst case you can use an alumina substrate for the circuit board.

Your choice of solder will need to be careful - especially if you expect to temperature cycle this device a number of times.

Resistors should be the least of your worries, but ensure they are derated significantly.

Capacitors will be tricky. Many modern dielectrics are temp sensitive as well as piezo electric. With the temperature change, the capacitors might start to generate current.

 

It's all going to be expensive and some of the stuff may be military spec, which might prove to be an issue for procurement.

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The key search term for your desire is DOWNHOLE --- combine that with MEASUREMENT or ELECTRONICS.

 

This search result is a wealth of information http://www.logwell.com

 

Stan

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ebrahim.rcii wrote:

  • What are the points that I must consider?

The very first thing to consider before taking on any project of any sort is: "Do I have the necessary skills & experience?"

 

 

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awneil wrote:
The very first thing to consider before taking on any project of any sort is: "Do I have the necessary skills & experience?"

 

On the other hand, the first thing that the customer should consider before taking on a supplier is: "Do they have the necessary skills & experience?"

 

It seems amazing that any sane drilling company would let such a project to a complete novice...

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:)

 

There is no company! We are four friends that decided to build this device. I think people will learn, just if they need to learn.(I did some good projects in some other field in this same way! And they are work fine now) I'll do it by the way, there is no time limit.
We are a team, and I am just responsible for the electric circuit. I'm not responsible for mechanical design.

 

And finally I appreciate if you teach me something more about the points that I must consider. For example, Which kind of resistor / capacitor and ... I must use? In this temperature how much the value (1k 2k ... 1mF 2mF in percent) change and so on.

 

Is it possible to buy military chips from TI? how I can prove them that I don't want to build a military device? (I must mention that I am in Iran! And some guys think we are terrorist!!!!! :| )

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And you just happen to have your own oil well?

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Everyone in Iran has a personal oil well.

 

Everyone in China has their own iron foundry.

 

Everyone in England has their own castle.

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awneil wrote:

And you just happen to have your own oil well?

:D

No,I just want to learn something!

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david.prentice wrote:

Everyone in Iran has a personal oil well.

 

So you think Iran is drilled everywhere?! :D
 

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ebrahim.rcii wrote:
Is it possible to buy military chips from TI?
The answer is dependent on who, or much more likely, what.

Consider that one of Texas Instruments' foci is geophysical electronics.

Is it possible to buy geophysical chips from TI?  Yes.

Is it possible to buy geophysical chips from TI's competitors?  Yes  wink

IIRC Atmel has some parts qualified to 150C.

ebrahim.rcii wrote:
how I can prove them that I don't want to build a military device? (I must mention that I am in Iran!
"them" is so broad.

Be as visible as possible with your actions and creations; that may, or should, open doors.

ebrahim.rcii wrote:
And some guys think we are terrorist!!!!! :| )
More precise is y'all may be "off the reservation" (may one who is of the First Nation consider pardoning me)

May the title "Republic" have meaning.

 

 

"Dare to be naïve." - Buckminster Fuller

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You should know that many chips that are specified to work at the outer limits of current technology (that includes high temperature) MAY be export limited to a number of countries (including Iran). You certainly will NOT be able to purchase military-grade or space-grade ICs from US companies (TI for example). Automotive-grade might or might not be export limited. Many EU companies follow a similar set of restrictions and they are very careful that things are not sent to some place allowed which is then sent to some place where it  is not allowed. 

 

Nobody can tell you what components to use when you do NOT even have a design. I can tell you that different ceramic capacitor types have very different temperature coefficients. NPO/COG is generally the best (typically for 10nf or less). The others include Z5U, X7R. X7R is "pretty good" while Z5U is "pretty bad" (temperature coefficient wise). Most resistors have temperature coefficients that you can ignore for all but high precision analog applications. Electrolytic capacitors die VERY quickly at such high temperatures.

 

Your BIG problem is going to be integrated circuits and batteries (batteries will start to "boil"). Capacitors will require care. Insulation not help you for more than a few hours, maximum - insulation simply slows the rate of temperature change and it does not PREVENT temperature change.

 

Please understand that we are not critical of your project. We are critical of the extreme performance that you have chosen with apparently no practical experience, including (apparently) little or no circuit design experience. We cannot teach this to you. Learning how to design at the outer limits of technology requires much more than a textbook knowledge of such things. From the questions you ask, it does seem that your experience is very  limited. Of course, you can continue, but you need to be aware that, even with the very best of intentions and hard work, you may not be successful. 

 

Best wishes,

Jim

 

Until Black Lives Matter, we do not have "All Lives Matter"!

 

 

Last Edited: Fri. Dec 19, 2014 - 07:02 PM
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gchapman wrote:

More precise is y'all may be "off the reservation" (may one who is of the First Nation consider pardoning me)

May the title "Republic" have meaning.

 

First of all, Thank you for the useful guidance. :) I appreciate you.

 

And second : We are NOT off the reservation bro! We are humanitarian. We don't want any nuclear bombs, We don't want any hungry child, we don't want soldier wounded in war, and any mother/father grieving. We are like you. we also want peace, smiles on the face of all the people on the earth. 

The war is between governments. They are destroying each other for the sake of POWER, they want to keep their power, and they use us for this bad goal! We love you, and you will love us if you know us. 

"When I know my enemy well enough to defeat him, then in that moment I fall in love with him!" -- A film. (This is we and you / you and us story, I think. )

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What you say is very important. However, the companies that make and sell technology to people in other countries must follow the rules set up by their governments. Otherwise, THEY could face big fines or jail.

 

It will not be a matter of convincing some person at TI or where-ever. It will be a matter of being approved by some faceless government bureaucrat. You have them, also. You cannot get away from them. The best you can do is try. If "they" won't sell to you, then look for something else. There is almost always more than one way to do it. And, there-by, you learn.

 

There are at least two other Iranians on this board. I suggest that you contact them to find out how they have been able to deal with component supply limitations.

 

Jim

 

Until Black Lives Matter, we do not have "All Lives Matter"!

 

 

Last Edited: Fri. Dec 19, 2014 - 09:51 PM
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If you want to learn, go get your masters in Electrical engineering, a masters in Mechanical engineering amasters in Software engineering. get 10-15 years of experience in mil-spec procurement, 5-10 years experience in import/export and 5-10 years experience in oil industry supply.

Once you do that, you have a small chance of making a working prototype, If you can throw $400,000 to $600,000 USD into development and validation.

BTW I usually underestimate it

 

Believe me I know.. I am there everyday

 

Keith Vasilakes

Firmware engineer

Minnesota

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ebrahim.rcii wrote:
No,I just want to learn something!

For learning, it is usually best to start with the basics and work up - rather than leap straight into the very extremes!

 

surprise

 

There is plenty to be learned and plenty of experience to be gained before you get anywhere near this kind of stuff!

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Last Edited: Sat. Dec 20, 2014 - 08:48 PM
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Make one out of commercial off the shelf parts. Test it in a chamber. Replace what fails with something tougher. Repeat this procedure several times. This might be called 'piecewise refinement' or 'spiral design'. I assume these things are on a cable that lowers it down, supplies juice, and sends data back. Jim mentioned 9000 PSI. If the top of the hole is open, how do you get 9000 PSI in it? (mostly sw... not much geology)

 

edit. cant spell. dislexic

 

 

Imagecraft compiler user

Last Edited: Mon. Dec 22, 2014 - 03:18 AM
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bobgardner wrote:
Make one out of commercial off the shelf patrs.

Even for that, you will still need a good grasp of electronics design, PCB design, software design, mechanical design, etc...

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If the top of the hole is open, how do you get 9000 PSI in it?

 

That's the ambient pressure.

 

JC 

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bobgardner wrote:

If the top of the hole is open, how do you get 9000 PSI in it? (mostly sw... not much geology)

It's not a hole. It is a pipe. an oil pipe.

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For strange and exotic applications, PIC will probably be a better choice as there is likely to be a flavor of PIC that works well for your application. It is not that Atmel is a bad choice, it has more to do with microchip having a million different PIC models.

 

I would start with atleast a uC that is rated for 125C, many automotive grade uCs are rated for 125C some are rated for 150C.

 

Flash memory does not like writing data at high temperatures, but it depends on your data rate and tolerance for errors. It would be a good idea to put in a checksum or writing the data twice to reduce memory errors.

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toalan wrote:
Flash memory does not like writing data at high temperatures, but it depends on your data rate and tolerance for errors. It would be a good idea to put in a checksum or writing the data twice to reduce memory errors.
One alternative is MRAM; up to 125C and has built-in ECC in its memory array controller.

EverSpin

SPI MEMORY INTERFACE FAMILY

http://www.everspin.com/products.php?hjk=SERIAL&a1f3=0

Edit:

A conventional way is by EEPROM; some of those also add ECC.

ON Semiconductor has some 1Mbit extended industrial 125C EEPROM, 1Mbit automotive 125C EEPROM, and a new 2Mbit 125C industrial EEPROM.

ON Semiconductor

Memory

http://www.onsemi.com/PowerSolutions/taxonomy.do?id=2205

"Dare to be naïve." - Buckminster Fuller

Last Edited: Sun. Dec 21, 2014 - 09:28 PM
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valusoft wrote:

Sounds like a question tailor-made for Neil.

 

 

Indeed. And of course it walks straight into confidential design data, so I can't go into details... but here are a few hints.

 

1) Ramtron do a 2Mb FRAM chip which will survive the temperature, though it's not rated to that level.

2) All small PIC processors are the wrong answer for pretty much any question; you're looking for low power - which means low speed - and high temperature; Microchip have some which can survive the heat; Atmel have half a dozen which are *rated* to the temperature. You can buy high temperature chips for most functions, but not all - and specialist chips are hundreds of dollars a piece.

3) For LSI logic, use NXP 74HC series rated at 125C; most of those are robust.

4) For power, pretty much your only option is primary lithium cells which are expensive and lethal if not handled properly. Everything else will fail.

5) Design for low power - less to preserve your battery, and more to minimise heat dissipation at the junctions.

6) Design for low mass - if you're at the bottom of a drill string you're looking at vibration up to 1000G.

7) Use lead-free solder and avoid any trace of bismuth, or your chips will just drop off the circuit board.

8) It *has* to be in a pressure chamber.

 

Before we allow anything down a hole, we need to know it will survive. In practice, we use components we've used for years; we know they can cope. For new stuff, well, I'm three hundred hours into a high temperature test at the moment; I will go at least as long again before I have confidence.

 

Neil

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barnacle wrote:
4) For power, pretty much your only option is primary lithium cells which are expensive and lethal if not handled properly. Everything else will fail.
Worked on one system with a primary cell that was lit by an ignitor; the cell is in a really hot environment and also had to supply a lot of current.

IIRC one test, the cell failed s.t. its case ruptured spilling extremely hot corrosive liquid over stuff.

Panasonic Industrial has some BR type coin cells that reach 125C.

Panasonic Industrial Devices

Non-Rechargeable Batteries: Lithium Batteries

http://na.industrial.panasonic.com/products/batteries/non-rechargeable-batteries/lithium-batteries

Panasonic Industrial Devices

Non-Rechargeable Batteries: Lithium Batteries

Selecting the Right Chemistry: BR-V-CR

http://na.industrial.panasonic.com/sites/default/pidsa/files/selecting_br_or_cr.pdf

"Dare to be naïve." - Buckminster Fuller

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barnacle wrote:
Atmel have half a dozen which are *rated* to the temperature.
mega88 is one; IIRC there was one thread here about mega64M1 at high temperature.

Atmel Corporation

AVR927: Using ATmega88 and ATA6832 for BLDC motor control in high temperature environment

http://www.atmel.com/images/atmel-4987-ata6832-dk-fully-integrated-bldc-motro-control_application-note.pdf (2.5MB)

4.2 High Ambient Temperature

(page 7)

describes the modifications to that DK for 125C and 150C.

"Dare to be naïve." - Buckminster Fuller

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DK?

 

Ross McKenzie ValuSoft Melbourne Australia

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Thank you very much. Really good points. looks very useful for me. 

 

I didn't understand this item :

6) Design for low mass - if you're at the bottom of a drill string you're looking at vibration up to 1000G.

 

My chamber goes underground in a oil pipe. I mean it is connected to a chain and floating in oil and going down. So why it must be low mass?

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I think that he was referring to a device on the drill; "drill string" IS "the drill". It sounds like ebrahim.rcii's application is  post-drill.

 

Hanging on the end of a chain, you DO NOT want low mass. After all, it needs to go down under its own weight. I'd bet that at 500 meters (9000 psi) what ever is in that well will be a LOT more dense than it is at the surface. So, you would want it quite a bit more dense than 1. That density, of course, will be the total mass divided by the exterior volume. 

 

You are going to have another challenge with package dimensions. At 45cm long and 25mm diameter and sufficient wall thickness to withstand the pressure, you are not going to have much working diameter inside. You will be able to get Li-Ion that are approximately "AA" size. And, there are camera batteries slightly larger. You won't be able to get anything as large as a C cell in that space.

 

In a pressure housing, the internal parts will be pretty well protected against pressure. But, the temperature WILL kill. And, getting that pressure RELIABLY ported into the pressure sensor is going to be a very difficult task. I had plenty of problems at 100m and 10-15C (open ocean thermocline). 

 

Jim

 

Until Black Lives Matter, we do not have "All Lives Matter"!

 

 

Last Edited: Mon. Dec 22, 2014 - 06:40 AM
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As Jim says - I had assumed you were on a drill, not in a pipe. My fault for not reading everything properly. Low mass is important for me to cope with high accelerations.

To manage high pressure we use some seriously tough pipes which contain the electronics packages with multiple seals to keep the oil and mud out. High pressure rated feed throughs are available to which wires can be soldered on either side and the feed through pressed into a machined hole - get it right first time because they won't come out in one piece.

Neil

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Thank you dear Neil and dear Jim. 

 

I am responsible for circuit design. I mean, all the mechanical design point have another person to work on. Now may I ask you give me some other points that I must consider for the circuit?

 

Best Kindly Regards. 

 

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valusoft wrote:
DK?
Development board or kit.

Atmel Corporation

Home > Products > Automotive > Drivers/High-Temperature ICs > High-Temp Drivers

ATA6832-DK

http://www.atmel.com/tools/ata6832-dk.aspx

"Dare to be naïve." - Buckminster Fuller

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ka7ehk wrote:
You will be able to get Li-Ion that are approximately "AA" size.
Li-ion are more likely to vent with flame as its temperature increases; IIRC Li-ion is on its third generation with an improved material mix to decrease the likelihood of that problem.

There are 1.5V AA and AAA lithium primaries (LiFeS2 or lithium iron disulfide) but these have a 85C to 90C PTC (overcurrent), a known defect above 60C (plastic outer insulator shrinks exposing more of the cathode), and a vent that operates at about 150C (explosion prevention when the cell is in a fire).

There are 3V coin, CR123, and CR2 lithium primaries (LiMnO2 or lithium manganese oxide).

There's another lithium primary, lithium thionyl chloride, at 3.6V per cell; I have no information on it.

What cells are used for downhole geophysical electronics?

My guess is a binary chemistry initiated with an ignitor; corrected, see correction.

Having to continually break/mate the pressure seal to refurbish or replace the PCB/battery might be a no-go.

Supercapacitors might work (one concern is volumetric efficiency) though do leak and IIRC leak more at high temperature.

Some supercaps are in a coin cell (stainless steel) form.

Edit: couldn't locate any greater than 85C supercaps.

Correction: https://www.avrfreaks.net/comment/1409861#comment-1409861

"Dare to be naïve." - Buckminster Fuller

Last Edited: Sat. Dec 27, 2014 - 07:47 PM
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toalan wrote:

For strange and exotic applications, PIC will probably be a better choice as there is likely to be a flavor of PIC that works well for your application. It is not that Atmel is a bad choice, it has more to do with microchip having a million different PIC models.

 

I would start with atleast a uC that is rated for 125C, many automotive grade uCs are rated for 125C some are rated for 150C.

 

Flash memory does not like writing data at high temperatures, but it depends on your data rate and tolerance for errors. It would be a good idea to put in a checksum or writing the data twice to reduce memory errors.

That comment is a baseless crock.

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I've been writing flash at 150C for about a quarter million writes per hour for the last four hundred (work time) hours. Still working... but not yet certified. We don't yet write flash at high temperature in the tool.

 

I don't know the make or type of the primary cells used, but they're sealed and certified for 175C. They need special handling and disposal and we're not allowed to have them in our development lab.

 

Neil

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ka7ehk wrote:
You will be able to get Li-Ion that are approximately "AA" size.
There are Li-ion for high temperatures but couldn't locate one in an AA size.

Encased in stainless steel.

Lithium primaries too (lithium thionyl chloride).

Ref.

Home

MP & Small VL

http://www.saftbatteries.com/battery-search/mp-small-vl

Saft prismatic MP and cylindrical small VL rechargeable cells are based on lithium-ion chemistry.

Excell Battery Company

Custom Lithium Primary, battery packs, pack, High capacity Metal cell

http://excellbattery.com/products/lithium-primary/

Excell Battery Co. also uses special thionyl chloride cells designed for the drilling companies in the oil industry. These cells are rated commonly to 150 °C but some models are rated for as high as 200 °C

"Dare to be naïve." - Buckminster Fuller

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My suggestion of "AA" size was based on ordinary  temperature batteries used in RFID readers I worked on. These were Panasonic cells assembled into packs by Mcro-Power. I confess to not checking the temperature range.

 

Jim

 

Until Black Lives Matter, we do not have "All Lives Matter"!

 

 

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PowerStream has 150C lithium primary cells size approx AAA and sub; some of these are sold quantity one.

PowerStream Power supplies, battery chargers, batteries and packs, dc/dc converters, injection molding

Primary Lithium Thionyl Chloride Cells from PowerStream

High Temperature Lithium Primary Cells (-20C to +150C)

http://www.powerstream.com/lip.htm#High%20Temperature

"Dare to be naïve." - Buckminster Fuller