Regenerating LICs - manufacurer's opinion (do not)

Hmmm, interesting, sounds like something we might try to verify in the road test....

"safety reasons" may need a bit more clarity... 

mine didn't blow up after charging Gough Lui has measured their capacity so his capacitors didn't blow up either... fortunately we have more than one capacitor of each type so we can plan more different test cases

Mine also did not burned. Under "regeneration" term I understand recovery of parameters. I think they will work well after recharging to the working range, but have reduced capacity and increased ESR.

A case of "kids!" do not try this at home...

www.youtube.com/watch

I think one has to be quite careful and I can completely understand why the manufacturer would not recommend this.

Mistreated LICs would likely suffer some permanent capacity loss and increased ESR, but this points to a microscopic structural change in the internal layers of the capacitor. Such changes, while they may not promote immediate failure, could be areas of increased stress. This may lead to latent failures in the field in the future, reduced lifetime (hours and cycles), potential sites for accelerated electrolyte degradation, potentially increased leakage and perhaps even reduced surge voltage tolerance. There is also the issue of whether this happens once-off or repeatedly - as the effects may also compound over multiple over-discharges.

I suspect it is perhaps something not so well studied, or the outcomes too variable and hard to control, so it's safer to err on the side of caution (especially if you are the company) and avoid customers using such parts at all.

Taking the parallel with more "dangerous" Lithium-Ion Batteries (LIBs) which have been over-discharged, you will find quite a few R-C hobbyists claiming to have "revived" such cells back to life. I've even done it on occasion just to learn - usually, deeply discharged cells lose half their capacity in my experience. But they come with drastic risks, especially when they have been over-discharged for too long, as internal copper dendrites may develop and separator damage may lead to increased probability of a thermal runaway (vent-with-flame) event some time in the future due to an internal short. As a result, it's not worth the risk of burning down one's abode simply for a $5 lithium-ion battery, but there are probably quite a few people who have "revived" such cells and gotten away with it (for now).

Thankfully, the construction of LICs means that such level of failure is rather unlikely. The sources I've read claim thermal runaway is not a possibility and the limited energy storage compared to LIBs means that the consequences are limited. But I would not consider the previously shorted LICs to be valid representatives for LICs in general ...

- Gough

It's a bit disappointing that manufacturers have not created a convention of (say) different-colored sleeving on these capacitors, so that when it comes to repairing boards, people don't accidentally discharge them.

They look almost exactly like normal capacitors : (

Older supercaps seemed to be following a convention of white colored sleeving (at least, all the ones I purchased a few years ago, from (I believe) two different manufacturers) were colored white, which is a more unusual color for a normal capacitor.

Hopefully PCB designers start making it clear on the board which parts are supercapacitors, perhaps with silkscreen, or even a bit of tape over any through-hole pads to prevent it accidentally touching metal for any extended periods, if the potential leakage of the tape and moisture/dirt on it is acceptable in the design.

Don't bet on it.

Remember that "supercapacitor" was originally the tradename for the first "electrical double-layer capacitors."

The idea of putting lithium on one of the electrodes created "hybrid supercapacitors."

So, while I agree such hybrids should have a pseudo-standard (or standard) for identifying them... let's not lump all "supercapacitors" into the same labeling requirements.

Related, what is the "standard" for the positive and negative indicators on a battery's quick-connect terminal?

That is interesting - I wouldn't consider colour to be a good indication as that has been used by brands to denote certain series or distinguish them from other competitor's products

I've seen ordinary capacitors in blue, black, orange, purple and green in various shades so far.

But I've also seen supercapacitors in black, yellow, blue, green, white and purple in my research thus far.

The first supercapacitor I may have seen would have been one for time backup in a Panasonic (Matsushita) VCR from the late 1980s that was one of their "GoldCap" series. They were sleeved in black and printed in gold - not unlike premium aluminium electrolytics of today.

Maybe we need some distinguishing feature, although I'm not sure colour on its own is enough ...

- Gough

Gough Lui said:

The first supercapacitor I may have seen would have been one for time backup in a Panasonic (Matsushita) VCR from the late 1980s that was one of their "GoldCap" series.

First LiC I saw was about 10 years later. They where quite bigger at that time.