I have a battery powered device (motion sensor) CR2032 or CR2477. I have consulted the sample designs and found that there is usually a capacitor with a value from 220uF to 330uF in parallel with the battery.
What happens if an uncharged capacitor is connected directly to a battery?
In my understanding, theoretically, when an uncharged capacitor is connected directly to a battery of, let's say, 9 volts, instantly the capacitor will be charged and its voltage will also become 9V. This will happen because there is no resistance between the capacitor and the battery, so the variation of current by time will be infinite.
This will happen because there is no resistance between the capacitor and the battery, so the variation of current by time will be infinite. Obviously, this is true when talking about ideal components and non-realistic circuits. I thought that doing it in real life would cause sparks, damaged components, explosions, or whatever.
Can a capacitor replace a battery?
Not exactly. While you can use a capacitor to store some energy, its ability to replace a battery is limited due to its low energy storage capacity. Capacitors vs batteries aren't interchangeable, but in specific use cases, capacitors can complement or assist batteries.
In your particular case, the reason there were no "dramatic effects," is that the battery and the capacitor have internal resistance. Therefore, the capacitor will not instantly charge up to the battery voltage. It will "slowly" charge up at the "normal" rate specified by the product of Rint and the capacitance C.
Why is the current flowing from a battery to a capacitor low?
Also, the current that flows from the battery to the capacitor is somehow of low magnitude, since it takes some considerable time to make the capacitor have the same voltage as the battery. I would like to know why this happens, thanks. This is an example of the circuit I talked about: Both the battery and the capacitor have an internal resistance.
Can a battery be connected directly to a capacitor?
However, I saw some videos and people usually do connect batteries directly with capacitors. Also, the current that flows from the battery to the capacitor is somehow of low magnitude, since it takes some considerable time to make the capacitor have the same voltage as the battery. I would like to know why this happens, thanks.