Hi,

For a large electrolytic capacitor (2200uF at 450Vdc), which has never ever been used but stored for an extended period of time (10 years in this case), will it perform and have a similar life expectancy after re-forming than a brand new one ? Or to rephrase, what can be the drawbacks of a reformed capacitor over new ones ?

Thanks
Matt

 

It will depend on the particular construction and electrolyte used and the storage conditions, principally the temperature.

 

Hi,

For a large electrolytic capacitor (2200uF at 450Vdc), which has never ever been used but stored for an extended period of time (10 years in this case), will it perform and have a similar life expectancy after re-forming than a brand new one ? Or to rephrase, what can be the drawbacks of a reformed capacitor over new ones ?

Thanks
Matt

The cap may have higher than spec ESR (equivalent series resistance). The ESR can be higher than expected because the metalized film can dissolve into the electrolyte. Thin metal film can make the cap vulnerable to high voltage leakage. Thin metal film can cause heating and failure if the circuit is loaded enough to cause significant ripple.

Reforming will rebuild the metal film and solve most problems. Shield the cap during reforming snd slowly turn up the voltage.