Once charged, for how long can a capacitor maintain its charge if it remains with the terminals turned off?
How long a capacitor maintains its load depends on several factors. The first is its value. A larger capacitor, theoretically, considering any leaks, can get longer charged. The second is precisely the leaks that can occur in two ways. The first is for air. In wet locations or days, the loss of charge is greater and the capacitor, especially those of smaller value, discharge faster. The second form of escape is the internal one. If the capacitor has an internal leakage, ie a low resistance between the armatures, the loads flow through this resistance and the discharge will be faster. In practice, high capacitors of the polyester or ceramic types are the ones that can hold the loads for a longer time. Electrolytes of very high values also, provided they are of good quality not having high leaks. Anyway, that is why it is recommended to be careful in your fiddling with disconnected circuits when they have capacitors of high voltage of high values (sources of tubes, for example).
