Permanent damage / degradation of ECAPs on polarity reversal for short duration

Thread Starter

enggricha

Joined May 17, 2014
86
Hi All,

Do Electrolytic capacitors suffer from permanent damage / performance degradation / rated life degradation - if they are subjected to short ( few seconds) of reverse voltage.

Background: I have a PCB that has electrolytic caps on the input and there is no reverse protection on the boards and there is no provision to add them at this time. If a user accidentally connects the input power with reverse polarity for short duration (enough to see the board not powering up) and then connecting again properly! How will it affect the electrolytic capacitors? The power supply voltage is 24V and the ECAP is 470uF / 50V.
 

Audioguru again

Joined Oct 21, 2019
1,486
On the car radio production line some hee-haws put a big electrolytic capacitor backwards so that all the workers can cheer when it exploded. The radios had a huge "idiot diode" across the power supply input to blow the fuse if the battery was connected backwards.

If reverse polarity occurs without protection then probably a lot more that just a capacitor will be destroyed in your product.
 

crutschow

Joined Mar 14, 2008
24,957
I would not count on there being no damage from the application of accidental reverse voltage. :eek:

You could kludge in a (physically) small P-MOSFET in series with the power input to provide reverse protection with essentially no forward voltage drop in normal operation.
 
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