Can ceramic capacitors be damaged by >100A inrush current? Electrolytics can... - Page 1
Forum section: electronics / projects

author: incf
author_rank: Frequent Contributor
timestamp: June 10, 2025, 07:33:18 pm
content: I recently ran into a situation where some 68uF solid polymer electrolytic capacitors seemingly were damaged by (failed short circuit after) being subjected to a large inrush current from a battery. Limited to ~80A. Failure possibly only occurred after mechanical shock due to improper shipping)Such large inrush currents are "bad" and to be avoided. However, sometimes they are necessary.Can ceramic capacitors fail due to similarly sized inrush currents?

author: Slh
author_rank: Regular Contributor
timestamp: June 10, 2025, 07:49:38 pm
content: Yes if either mechanical shock has already weakened them (so they crack, fail short circuit and release the magic smoke) or the resultant over voltage from the LC circuit kills them (with a short circuit followed by magic smoke).I recommend also potting them so it's really hard to tear down and diagnose...

author: Gyro
author_rank: Super Contributor
timestamp: June 10, 2025, 08:00:36 pm
content: All capacitors can be be damaged by high enough dI/dt. In the case of ceramics, there is a junction between the contacts and the metalization [Edit: Polymer electrolytics can also have weak spots depending on construction]. Foil type capacitors will tend to be more robust - you might find that low ESR standard Aluminium electrolytics are more robust in this application.

author: wraper
author_rank: Unknown
timestamp: June 10, 2025, 08:03:46 pm
content: Quote from: Gyro on June 10, 2025, 08:00:36 pmFor many of them it's physically impossible (unless applying voltage higher than rated) because inrush current will be inherently limited to a safe level due to their ESR.

author: TimFox
author_rank: Super Contributor
timestamp: June 10, 2025, 09:27:01 pm
content: If the 100 Areallyflows into the capacitor, it should charge it up to a dangerous voltage.Of course, that should be limited by the voltage compliance of the actual source of current, or a resonant circuit with loss that contains the capacitor.

author: incf
author_rank: Frequent Contributor
timestamp: June 10, 2025, 09:35:40 pm
content: My 2x 68uF 50V rated solid polymer capacitors had a 33V SMB TVS across them when they got charged to ~24V with a ~80 amp inrush current (shunt current measurement resistors limited inrush) - I'd think that would have been sufficient to avoid overvoltage during the short inrush transient.

author: thm_w
author_rank: Super Contributor
timestamp: June 10, 2025, 10:20:46 pm
content: I find this hard to believe. But here is a quote from Panasonic oscon cap:QuoteDid you remove both capacitors from the board, and now measured and both are short circuit? What is the part number of the capacitor?

author: Manul
author_rank: Super Contributor
timestamp: June 10, 2025, 11:12:34 pm
content: High-K ceramic capacitors are certainly not the most robust type and can fail. I believe piezoelectric effect plays a role here, cause high dI/dt essentially creates a mechanical shock. Film type capacitors are the most robust, they can often handle pulses in kA ranges. In your application, standard electrolytic capacitors should handle the inrush too. I don't know what happened with your solid polymer ones, never seen them get shorted.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: June 10, 2025, 11:34:56 pm
content: May not only be inrush current. if power is applied very suddenly, e.g. by plugging in or a physical switch, the fast rising edge can combine with wiring inductance and the low impedance of the capacitor to cause ringing which may exceed the capacitor's voltage rating, causing breakdown, and then the high current available finishes off the job.

author: coppercone2
author_rank: Super Contributor
timestamp: June 11, 2025, 12:41:37 am
content: I think you might need those ceramic single layer capacitors that people mistakenly make fun of for this job. Probobly one of the most robust caps out thereUnfortunately its going to be in the nF range.