Return to Answer

Ah, youth...

Electrolytic capacitors 'blow up' when they fail in a shorted condition. One failure cause is being exposed to higher-than-rated voltage. Another way is to connect them in reverse. Either way, once this happens, the current begins to flow across the short, heating up the capacitor, something which which you seem to have observed already.

Stand-up (radial) electrolytic caps have scribe lines in the top that allow the cap to 'vent' when it fails. This allows the pressure to escape, so they don't explode (usually.) Instead, they sort of 'fizz' as they electrolyte heats up and vaporizes, which vents out the top by breaking through the scribe. Hit them with enough energy and they will 'spill their guts' as the electrolyte and foil are ejected from the casing.

Now, why didn't your cap do that? 9V batteries however don't supply a lot of current. This limits the amount of heating that will occur across the failed cap. So it won't heat enough to do anything interesting. But, you will have destroyed the cap anyway (check it with a voltmeter.)

You'll have more... dramatic results with a battery that can provide more power (current, really), such as a 12V automotive type.

Nevertheless, please use caution. Eye protection strongly recommended. Putting the cap under a plastic shield while you do this is also a good idea. Avoid breathing the emitted fumes as they're irritating and toxic.

Ah, youth...

Electrolytic capacitors 'blow up' when they fail in a shorted condition. One failure cause is being exposed to higher-than-rated voltage. Another way is to connect them in reverse. Either way, once this happens, the current begins to flow across the short, heating up the capacitor, something which which you seem to have observed already.

Stand-up (radial) electrolytic caps have scribe lines in the top that allow the cap to 'vent' when it fails. This allows the pressure to escape, so they don't explode (usually.) Instead, they sort of 'fizz' as they electrolyte heats up and vaporizes, which vents out the top by breaking through the scribe. Hit them with enough energy and they will 'spill their guts' as the electrolyte and foil are ejected from the casing.

Now, why didn't your cap do that? 9V batteries don't supply a lot of current. This limits the amount of heating that will occur across the failed cap. So your cap won't heat enough to do anything interesting. But, you will have destroyed the cap anyway (check it with a voltmeter.)

You'll have more... dramatic results with a battery that can provide more power (current, really), such as a 12V automotive type.

Nevertheless, please use caution. Eye protection strongly recommended. Putting the cap under a plastic shield while you do this is also a good idea. Avoid breathing the emitted fumes as they're irritating and toxic.

Ah, youth...

Electrolytic capacitors 'blow up' when they fail in a shorted condition. One failure cause is being exposed to higher-than-rated voltage. Another way is to connect them in reverse. Either way, once this happens, the current begins to flow across the short, heating up the capacitor, something which which you seem to have observed already.

Electrolytic caps have scribe lines in the top that allow the cap to 'vent' when it fails. This allows the pressure to escape, so they don't explode (usually.) Instead, they sort of 'fizz' as they electrolyte heats up and vaporizes, which vents out the top by breaking through the scribe. Hit them with enough energy and they will 'spill their guts' as the electrolyte and foil are ejected from the casing.

Now, why didn't your cap do that? 9V batteries however don't supply a lot of current. This limits the amount of heating that will occur across the failed cap. So it won't heat enough to do anything interesting. But, you will have destroyed the cap anyway (check it with a voltmeter.)

You'll have more... dramatic results with a battery that can provide more power (current, really), such as a 12V automotive type.

Nevertheless, please use caution. Eye protection strongly recommended. Putting the cap under a plastic shield while you do this is also a good idea. Avoid breathing the emitted fumes as they're irritating and toxic.

Ah, youth...

Electrolytic capacitors 'blow up' when they fail in a shorted condition. One failure cause is being exposed to higher-than-rated voltage. Another way is to connect them in reverse. Either way, once this happens, the current begins to flow across the short, heating up the capacitor, something which which you seem to have observed already.

Stand-up (radial) electrolytic caps have scribe lines in the top that allow the cap to 'vent' when it fails. This allows the pressure to escape, so they don't explode (usually.) Instead, they sort of 'fizz' as they electrolyte heats up and vaporizes, which vents out the top by breaking through the scribe. Hit them with enough energy and they will 'spill their guts' as the electrolyte and foil are ejected from the casing.

Now, why didn't your cap do that? 9V batteries however don't supply a lot of current. This limits the amount of heating that will occur across the failed cap. So it won't heat enough to do anything interesting. But, you will have destroyed the cap anyway (check it with a voltmeter.)

You'll have more... dramatic results with a battery that can provide more power (current, really), such as a 12V automotive type.

Nevertheless, please use caution. Eye protection strongly recommended. Putting the cap under a plastic shield while you do this is also a good idea. Avoid breathing the emitted fumes as they're irritating and toxic.

Ah, youth...

Electrolytic capacitors 'blow up' when they fail in a shorted condition. One failure cause is being exposed to higher-than-rated voltage. Once this happens, the current begins to flow across the short, heating up the capacitor, something which which you seem to have observed already.

Electrolytic caps have scribe lines in the top that allow the cap to 'vent' when it fails. This allows the pressure to escape, so they don't explode, they sort of 'fizz' as they electrolyte heats up and vaporizes.

Now, why didn't your cap do that? 9V batteries however don't supply a lot of current. This limits the amount of heating that will occur across the failed cap. So it won't heat enough to do anything interesting. But, you will have destroyed the cap anyway (check it with a voltmeter.)

You'll have more... dramatic results with a battery that can provide more power (current, really), such as a 12V automotive type.

Nevertheless, please use caution. Eye protection strongly recommended. Putting the cap under a plastic shield while you do this is also a good idea.

Ah, youth...

Electrolytic capacitors 'blow up' when they fail in a shorted condition. One failure cause is being exposed to higher-than-rated voltage. Another way is to connect them in reverse. Either way, once this happens, the current begins to flow across the short, heating up the capacitor, something which which you seem to have observed already.

Electrolytic caps have scribe lines in the top that allow the cap to 'vent' when it fails. This allows the pressure to escape, so they don't explode (usually.) Instead, they sort of 'fizz' as they electrolyte heats up and vaporizes, which vents out the top by breaking through the scribe. Hit them with enough energy and they will 'spill their guts' as the electrolyte and foil are ejected from the casing.

Now, why didn't your cap do that? 9V batteries however don't supply a lot of current. This limits the amount of heating that will occur across the failed cap. So it won't heat enough to do anything interesting. But, you will have destroyed the cap anyway (check it with a voltmeter.)

You'll have more... dramatic results with a battery that can provide more power (current, really), such as a 12V automotive type.

Nevertheless, please use caution. Eye protection strongly recommended. Putting the cap under a plastic shield while you do this is also a good idea. Avoid breathing the emitted fumes as they're irritating and toxic.