Electrolytic capacitors in Electric car charger - Page 1
Forum section: electronics / general

author: Faringdon
author_rank: Super Contributor
timestamp: October 09, 2021, 10:03:47 pm
content: hi,The Standard electric car charger should last 10 yearsDoes it contain electrolytic capacitors?If so, what is the lifetime calculation for them?

author: bob91343
author_rank: Super Contributor
timestamp: October 10, 2021, 02:11:51 am
content: Electrolytic capacitors generally have much longer lifetimes than 10 years.

author: bdunham7
author_rank: Super Contributor
timestamp: October 10, 2021, 04:46:49 am
content: Quote from: Faringdon on October 09, 2021, 10:03:47 pmThat seems a rather large and unsubstantiated generalization!QuoteWell, I suppose it could be repaired if that was all that was wrong with it. But I wouldn't order the parts just yet. I'm repairing an old and rather complex device right now that has hundreds of capacitors, and I'm replacing quite few of them--mostly tantalum beads. I haven't had a bad electrolytic yet on this unit, but all of the polypropylene film caps are bad. So perhaps best to worry about something else.

author: Faringdon
author_rank: Super Contributor
timestamp: October 10, 2021, 08:30:43 am
content: QuoteThanks, thats true, but there are poor quality "85degc, 1000hr" electrolytic caps, and there are indeed much higher quality "10000hr,125degc" ones.Nobody knows which are used.QuoteThanks , but a dead electro can well result in overvoltages to the components in the vicinity, as such, no repair can realistically be done. And sometimes, if a component suffered overvoltage stress, then it may not fail then, but its lifetime would be much reduced. As such, post failure repair begs questions.....of course, re-capping after so many years would doubtless be a good idea.....but have the caps been mounted in a spot which makes it easy to take the el caps out and replace them?

author: Siwastaja
author_rank: Super Contributor
timestamp: October 10, 2021, 08:50:36 am
content: Electrolytic capacitors are not the only component which can be dimensioned poorly or penny-pitched. I wouldn't concentrate on electrolytic capacitors only, but design and assembly quality as a whole.High-quality, properly dimensioned elcaps are still quite small part of the product cost and easily allow 15-year lifetime in usual household environment, so unless it's absolute race-to-the-bottom toy product, it makes no sense to pitch pennies here. Of course, due to some mismanagement, this can happen, but so can many other failures too.

author: wraper
author_rank: Unknown
timestamp: October 10, 2021, 09:03:58 am
content: Quote from: Faringdon on October 10, 2021, 08:30:43 amTemperature rating says very little about actual quality.Also if the product is designed properly, a decent 85oC cap will last for many decades.QuoteIt's untypical for failed electrolytic cap to cause overvoltage, unlike failures of other parts.

author: Faringdon
author_rank: Super Contributor
timestamp: October 10, 2021, 09:11:22 am
content: QuoteAgreed. Though as in this video, there are high quality and low quality el caps, of whichever description......as in at 6:03

author: Siwastaja
author_rank: Super Contributor
timestamp: October 10, 2021, 09:17:57 am
content: Payback for li-ion home energy storage is iffy, but that's due to the still relatively high $/kWh of the li-ion cells - which themselves may have lifetime between 10-15 years. Elcaps play no role in that.I'm currently working with energy storage systems based on water and heat pumps, with the obvious and quite dire limitation of only being able to store heat, but heating is #1 energy consumer in colder climates anyway. Funnily, a lot of such energy storage systems were installed here in 1970's and 1980's which now sit unused or get dismantled while a shiny new air-to-water or ground source heat pump is installed next to it, ignoring the existing 100kWh storage. Then, the same people are sold tiny 10kWh li-ion storage systems for 5000€.

author: Siwastaja
author_rank: Super Contributor
timestamp: October 10, 2021, 09:21:31 am
content: Reliable design with Elcaps is fairly easy. In a nutshell:* Buy Panasonic, Nichicon, etc, well known brands.* Don't use the lowest rated 1000hr parts. 5000-8000hr parts are available.* Actually calculate, simulate or measure ripple current. Derate by some 40-50%.* Derate voltage by some 20-30% or more.* Derate ambient temperature by some 20 degC or more, i.e., 85degC part goes up to around 60degC. Otherwise, use a 125degC part. Remember that "ambient" is the local ambient at the capacitor. As they bypass ripple currents and need to be close for low ESL, there usually is a heat source nearby.This means you need to pay $2 instead of $0.50 for the elcaps in a $2000 product. So what.

author: wraper
author_rank: Unknown
timestamp: October 10, 2021, 09:39:54 am
content: Quote from: Faringdon on October 10, 2021, 09:11:22 amThose LOW ESR Capxon were defective by design (they could bulge even while staying on the shelf for a few years), and were used in hot environment with high ripple current, which contributed to the failure. On other hand, general purpose series from Capxon had no such issues. Not to say they were produced at the time of "capacitor plague" in 2000's when a lot of defective LOW ESR capacitors were produced by several manufacturers. Capacitor plague is long gone and even cheap capacitors these days last quite long.

author: Faringdon
author_rank: Super Contributor
timestamp: October 10, 2021, 01:25:57 pm
content: It also makes you wonder...maybe the el caps in the high power stage have been designed and spec'd properly, but then if theyve overlooked some little el cap in a tiny bias supply, and that bias supply going down takes the whole system down......just sayin'

author: Siwastaja
author_rank: Super Contributor
timestamp: October 10, 2021, 01:38:08 pm
content: Yes, exactly that happens and those who like to repair things often find some tiny bias supply elcap died.For high reliability stuff, designers need to be competent and careful not to overlook any part of the circuit.

author: bdunham7
author_rank: Super Contributor
timestamp: October 11, 2021, 12:10:28 am
content: Quote from: Siwastaja on October 10, 2021, 01:38:08 pmI repair stuff and the large majority of bad el-caps are simply non-prime capacitors in thermally challenging environments and sometimes marginal operating conditions. Some of those 'tiny' capacitors are actually overworked because nobody paid attention to that part of the circuit or, god forbid, did any actual testing. The next most common scenario would be the occasional very old unit that is otherwise well designed. Then there's the ones that fail because something else went wrong.I cannot think of a unit that I've repaired recently where an electrolytic capacitor went bad where any further damage was done. I can't say the same for the fire-starting tantalums.