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You can achieve a decent lifespan increase when the operating voltage is lower than the maximum rated voltage. The most conservative estimate is that lifespan doubles when the component is operated at 50% of the rated voltage
It is the ripple current that the cap is delivering is the culprit. Well, the current along with the electrolyte series resistance, to be accurate.These caps have essentially just a few mA of ripple current in them. If the product was permanently connected to the mains 24/7, and with day temperatures of 40degc, then how long would they last?
Surely that electrolyte is going to dry out sooner or later?
Thanks, that sounds right, but as we know, the seal must allow gas to escape, since over time, electrolytics gradually produce gas anyway, and it will cause too much pressure if not allowed to seep out........so the seal must be "leaky", and here lies our problem.....it is the situation with wet electrolyte...it simply leaks gas over time as it drys out, this gas leaks out of the seal as it must do......so isnt this the problem with all wet electrolytes?If the seal is not made to 6-sigma manufacturing standards then there will be variations in parts
These caps have essentially just a few mA of ripple current in them. If the product was permanently connected to the mains 24/7, and with day temperatures of 40degc, then how long would they last?
Thanks, i see your point, but its a shame that the Aluminium electrolytic capacitors' datasheets dont state whether or not this "non venting operation" has been facilitated.Any gases produced can and do react with the Aluminium, hence limiting the pressure and the need to "vent" - thus fully sealed and long life caps can exist ...
The doubling of rate (given by the Arrhenius equation) for every 10C increase in temp is a very crude approx for processes that take place at a reasonable rate around the room temp. It is messy to explain here and I make the reference to https://chemistry.stackexchange.com...ure-increase-doubles-the-rate-constant-k-whenCapacitor application notes usually refer to lifetime expectancy calculation with doubling every 10 K. Respectively a 1000h/105°C rated capacitor achieves about 10 years at 40°C with effective no self heating (actual ripple current < 10% of rated current). The calculation is somehow inaccurate due to the large extrapolation factor. If you want larger margin, you can use a capacitor with 5000h/105°C specification.
I doubt it; possibly it was true in the good old days but modern electrolytic capacitors do not produce gas unless you go significantly above the rate voltage for some extended time (means short voltage spikes won't cause any indigestion). I strongly suggest that you keep a 10% headroom on the working voltage.Thanks, i will try and find it, the doc which states that very minor "gas leakage" out of an electro is not only normal,
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