Is this a safe way to charge a supercap?

Thread Starter

-live wire-

Joined Dec 22, 2017
I want to make something that charges some supercaps I have (7.5 F 5.5V) in parallel and discharges them in series (to step up the voltage, get some high current limits too). I have a 6V 6A power supply to charge them up (the voltage will be reduced to 5.3V with

My plan is to use properly rated mosfets to achieve this series/parallel switch (I know it's a lot to do this, but I found a good deal). The mosfets will get here in about a month (arg), so I am in no rush. I am going to measure the voltage at various points with an arduino and some voltage dividers for protection and to know when it is ready to discharge. Because there is a high current limit on the input, and the supercaps will probably explode if the voltage is exceeded, it is important to have good protection. So is a voltage divider to measure the voltage after the diode that then tells the arduino to shut off a mosfet if the voltage is exceeded enough? I do not want to make this too expensive or that complicated, so if the diode and arduino is enough to safely charge them, let me know. If it is not, please suggest a good alternative. Thanks. Also, any suggestions for the project in general are welcome.


Joined Oct 2, 2009
You are missing a lot of information.
What is the charge current?
What is the discharge current?
What is the application of this supercap? Where/what is the rest of the circuit?


Joined Aug 21, 2008
I use a switching regulator powered by a 5V Wall Wart. The current limit and voltage limit are selected for the particular capacitor and the desired voltage.

Thread Starter

-live wire-

Joined Dec 22, 2017
I plan to do something a little like this but without the high voltage (only up to 30V) and with a diode to reduce voltage and mosfets where the resistors and air gaps are. Plus there will be some voltage dividers for measuring the voltage. So the supercaps will probably draw about 5 amps, and discharge at a few amps. The application is amplifying power for a short-ish duration.

P.S. Could anyone recommend a good circuit schematic thing that is free, easy to use, and doesnt require a download?


Joined Sep 24, 2015
There have been times I've wondered about connecting two 12 volt batteries together in such a way that I can get 24 volts out of it but charge it from a 12 volt charger. Looking at the diagram you post, with those 1 and 10 meg ohm resistors, you're really going to have to wait a very long time to charge those up to their full charge. Likely you'll need several shaves and at least two hair cuts before that circuit can charge a super cap. So I'm wondering if this is how you intend to approach this subject. If so - I'm most certainly interested in your solution.