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Is it possible for a 100u or 10u electrolytic capacitor to operate at -30C ambient temperature?

What type of capacitors can this be replaced for such low temperatures to operate fine and better stability?

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  • \$\begingroup\$ Silicon capacitors might be a good choice (expensive though). Here' a document that measures a few standard types down to cryogenic temperatures (NP0 does well): hal.archives-ouvertes.fr/hal-00623399/document \$\endgroup\$ – HKOB Jun 6 '18 at 6:42
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  • Operating temperature range

The Operating Temperature Range is the temperature range over which the part will function, when electrified, within the limits given in the specification. It is the range of ambient temperatures for which the capacitor has been designed to operate continuously. Largely the formation voltage sets the high-temperature limit. Higher formation voltages permit higher operating temperatures but reduce the capacitance. The low-temperature limit of an electrolytic capacitor is set largely by the cold resistivity of the electrolyte. The higher cold resistivity increases the capacitor’s ESR 10 to 100 fold and reduces the available capacitance.

The electrolyte is a complex blend of ingredients with different formulations according to voltage and operating temperature range. The principal ingredients are a solvent and a conductive salt – a solute – to produce electrical conduction.

The common solvent is ethylene glycol (EG) and is typically used for capacitors rated –20 ºC or –40 ºC. Dimethylformamide (DMF) and gammabutyrolactone (GBL) are often used for capacitors rated –55 ºC. Common solutes are ammonium borate and other ammonium salts.

  • Storage Temperature Range

The Storage Temperature Range is the temperature range to which the part can be subjected unbiased, and retain conformance to specified electrical limits. It is the range of ambient temperatures over which the capacitor may be stored without damage for short periods.

For long periods of storage keep capacitors at cool room temperatures and in an atmosphere free of halogen gases like chlorine and fluorine that can corrode aluminum. Storage temperature ranges are from –55 ºC to the upper limit of the operating-temperature ranges.

Sources:

Capacitor Selection Guide - KEMET (.PDF)

Aluminum Electrolytic Capacitor Application Guide - Cornell Dubilier (.PDF)

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To be honest I have never seen an electrolytic capacitor with a minimum temperature rating. They and most capacitors DO have a maximum temperature rating.

Most are rated to 85 C but for SMPS and other power devices you may need to buy 105 C rated versions. An 85 C capacitor exposed to 100 C will have a short life. It may dry up and do nothing, or pressure build-up may make it go BANG.

I had to do a bit of research for marketing one day to find out how cold our products could get and still keep working. The weak spot was the LCD surge counter, which froze at -40 C/F. The liquid crystal itself froze and would not change state until it was nice and warm again.

If you are planting a device in brutal cold weather the batteries should be your main concern, not capacitors. Some parts may drift a little in such cold. If temperature goes below -100 C, you risk cracking of the solder to ICs.

Except for LCD displays, cold should not be an issue with stable parts down to -40 C/F. Below that, your on your own.

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If you go to digikey.com and start looking at electrolytic caps, their filter system gives 11 different 100 uF caps rated for -55 to +150 C. So it's not what you call a real problem.

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Aside from noting that there are electrolytic caps rated for < 30C, if you are worried about performance you could use hybrid aluminum polymer caps as generally better replacements at cold (if ESR is your figure of merit).

I've linked a couple datasheets; check the ESR vs. temp graph on hybrid polymers (pretty much flat to -40C) and ESR values in the standard electrolytic table (go from 0.2Ohm to 3 Ohm between 20C and -40C).

Hybrid Polymer vs. Standard

You cannot just use standard (e.g. not hybrid) polymer if you care about similar performance against high vibration or humidity.

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