Electrolytic capacitor life calculator - Page 1
Forum section: electronics / projects

author: Jester
author_rank: Frequent Contributor
timestamp: September 06, 2022, 01:19:09 am
content: I found this calculator while searching for Electrolytic capacitor life vs. temperaturehttps://eepower.com/tools/electrolytic-capacitor-life-calculator/#I have no idea how accurate it is. It does not use ripple current as an input.If you enter voltage and temperature matching the capacitors specifications it returns the expected load life for example 3000hrs, what's interesting is how much the load life gets extended with lower ambient temperature and voltage. So for example if a 25V, 105 deg cap operates at 12V and 45 deg C, the projected life increases to 384,000 hours or 43 years of continuous use.

author: Someone
author_rank: Super Contributor
timestamp: September 06, 2022, 01:25:26 am
content: Different manufacturers have provided different equations for their capacitors life estimation (including different equations for different models/series from the same manufacturer). So rather than relying on some unreferenced online "calculator", you go to the manufacturers data.

author: Jester
author_rank: Frequent Contributor
timestamp: September 06, 2022, 01:40:45 am
content: Quote from: Someone on September 06, 2022, 01:25:26 amI'm familiar with the rule of thumb "life doubles for every 10 degree drop in actual temperature"I was not aware of significantly extended life for operating at lower than specified voltage.

author: Someone
author_rank: Super Contributor
timestamp: September 06, 2022, 01:59:10 am
content: Quote from: Jester on September 06, 2022, 01:40:45 amExcept that isn't a rule that applies in general/all cases:https://www.chemi-con.co.jp/en/faq/detail.php?id=29BDBH5Quotehttps://chemi-con.com/capacitor-life/QuoteI'll stick to trusting the manufacturers, not some random unreferenced "information" from the internet. At some point the majority of "information" floating around the internet is actually incorrect/wrong, as its easy to condense things to the point they no longer apply/make sense and the easy/short version gets shared and multiplied, while its hard to communicate the accurate/complete information.

author: bdunham7
author_rank: Super Contributor
timestamp: September 06, 2022, 02:58:42 am
content: There are different models and different sizes, designs and chemistries involved, so there are probably some reasonable differences in projections. I've seen claims that voltage matters little for capacitors under 100V, but has some role at higher voltage ratings.That calculator you posted is crap, IMO, because it uses ambient temperature without regard to ripple or discharge currents. Not accounting for the temperature rise in operation seems to me to be a pretty serious shortcoming. Also, I don't know of any manufacturer or reliable source that uses that mathematical model for voltage in the general case.

author: SiliconWizard
author_rank: Super Contributor
timestamp: September 06, 2022, 04:41:03 am
content: Well, it's based on the Arrhenius law, which is pretty much what is used for the estimation of life for most components even including semiconductors.The tricky part of this law is always the coefficients. And those are usually chosen very empirically. So do not expect something very accurate here, just a very rough idea.

author: Siwastaja
author_rank: Super Contributor
timestamp: September 06, 2022, 11:46:10 am
content: Even if the calculator had the right coeffs for temperature and voltage (which it likely does not), it completely misses the ripple current factor which is probably the most important part of the model.

author: srb1954
author_rank: Super Contributor
timestamp: September 06, 2022, 01:44:28 pm
content: Quote from: Siwastaja on September 06, 2022, 11:46:10 amVishay has an on-line calculator for electrolytic capacitor life estimation:https://www.vishay.com/en/capacitors/calc-alucaps-lifetime/This calculator accounts for temperature and ripple current but doesn't make any mention of a voltage effect on lifetime.

author: Siwastaja
author_rank: Super Contributor
timestamp: September 06, 2022, 03:22:58 pm
content: Quote from: srb1954 on September 06, 2022, 01:44:28 pmThis is likely because voltage has a secondary, derived effect in a sense that if you buy a capacitor with higher rated voltage, it will come in a larger can, so has more surface area for cooling. But for the same reason, it already has higher rated ripple current, so it's the primary parameter one should see in a formula.Some people who want to ballpark things in a difficult, indirect manner choose to ignore ripple current ratings and opt for some weird voltage derating factors.Applied voltage has some interesting effects though, too much and leakage current rises sharply, too little and the capacitor needs gradual conditioning after years of storage (or use at low voltage) before applying higher voltage.

author: oz2cpu
author_rank: Frequent Contributor
timestamp: September 06, 2022, 04:41:02 pm
content: even at ZERO voltage, and ZERO current, and constant room temperature,electrolytics dont last forever.