# Discharging a capacitor to a battery supply [simple circuit]

If I have the following circuit... (resistor & capacitors values are made up) ...and I hold down SW3 until the capacitor is charged, then I release SW3 then hold down SW1 why wouldn't the capacitor discharge into the negative terminal of the battery? (according to the comment I posted on this question: Capacitors and simple circuit understanding)

I think I've misunderstand some fundamentals here, as in my mind this circuit would be OK.

• Unless BAT1- is connected to the circuit GND, there will be no current flow to charge C2. – theorifice Aug 6 '16 at 15:10
• Ground capacitor lower terminal. Connect Sw3 from top of cap to ground to get hard discharge or top of R1 to get slower discharge. Current path MUST be via a continuous circuit. – Russell McMahon Aug 6 '16 at 16:37

• Correct regarding the multimeter. I mentioned this in the other answer. As an instructive experiment charge up your capacitor to 9 V and let go SW1. Then put the meter across it and time how many seconds it takes to discharge by 63% (to about 3 V). Now you should find the time constant $\tau = R \times C$ where R is the input resistance of the meter. – Transistor Aug 6 '16 at 15:31