# Capacitor charge holding time?

I have a circuit of capacitor connected to a 12 v DC source. As soon as circuit is closed, yes the capacitor slowly charges itself until it attains the same voltage of the supply source. Eventually, it has fully charged and get 12 v voltage now.

Now, my big confusion is that....how long can I connect this capacitor which has now 12 v voltage with the supply source?? If I continue to connect for over 24 hours straight, will there be any negative impact on the capacitor or the source?? Thanks.

## 1 Answer

Once it is charged, then it is charged.

Remember Q=It

Q is charge, I is current and t is time...

• Ok sir. But my question is....can I keep the capacitor in the circuit like 24 hours straight??? Or, what would happen if I do not remove the capacitor after being fully charged?? Any heat issues will arise within the circuit Aug 30 '19 at 5:36
• yes, and nothing. Some capacitors are connected for 8760 hours a year... Aug 30 '19 at 5:37
• Okok thanks for the confirmation. My project is...I would have a circuit which will be power by 12 v DC only when car engine is running. Then, in time t =5 secs, the capacitor will fully be charged while engine still running or maybe still running for 5 or 6 hrs....still then capacitor is full. Now, the main point..as soon as engine is OFF, the capacitor will be discharged which will activate a relay to turn on the load bulb connected to this relay as long as the charged is in the capacitor. Could you kindly sketch a diagram of this project. Thanks. Aug 30 '19 at 5:43
• Write your real question properly including pertinent information. I have answered the question you asked originally so please upvote and/or accept it. Aug 30 '19 at 5:44
• I won't be answering that question until you accept the answer I gave - just to try to get you to change your habits, not because I need points - I don't... Aug 30 '19 at 5:54