Potentially daft Supercapacitor related question, this is rated at 25V!

[bsodmike]

Hi all,

I've got a 82mF Supercapacitor rated at 25V
https://export.farnell.com/kemet/als70a823df025/cap-82000-f-25v-alu-elec-screw/dp/2729143

Every article/video I can find on the subject, usually refers to an operational voltage of 2.5V; even the "Balance" chargers / Voltage safety PCBs on eBay are listed to work at 2.5Vdc.

My obvious assumptions about this supercapacitor:

• Charge voltage should be ~90% of the max, so around 22.5VDC.  Can we charge at 25VDC?
• Charging at around 0.5A to 1A should be safe?  Normally, the rule is not to exceed "1C" of a single cell, well at least for LiPos; a 1000mAh Lipo can be charged at 1A safely.  Does this apply here as well?
• Minimum voltage: Unclear, thoughts?

Rough back of the paper calculations say 25V at 82mF can provide a max energy of 7.1mWh.  Given that a 9VDC battery has ~5.5Wh capacity, means this Supercapacitor can hold ~770 less energy? (Anyone able to double check these numbers?).

Thanks!
Cheers M.

[wraper]

It's not a supercapacitor. Just a large aluminum electrolytic capacitor.

[Gyro]

The PDF datasheet is on that page too.

[rsjsouza]

Indeed. The ones below are super capacitors, which usually start at many Farads, not micro or milli Farads.
https://www.newark.com/c/passive-components/capacitors/supercapacitors/prl/results

[bsodmike]

Oh nuts, sorry that was a normal cap for different project

Right here’s a Supercal 5F but rated at 12V. Does this mean it’s minimum voltage should not drop below 12V?
The data sheet does not mention minimum voltage limits.

https://export.farnell.com/kemet/fs1b505zf/cap-5f-12v-super-cap-radial/dp/2777893

Thanks!

Cheers M

[Gyro]

Looking at the datasheet, that is a memory / low current standby capacitor. It has a 4 ohm internal resistance and charge / discharge currents in the mAs range - 18mA discharge is mentioned.

12V is the maximum voltage you can put across it. You treat it like a capacitor, not a battery, ie. it discharges to zero volts.

[bsodmike]

Aha that makes sense!!  Thanks