# If I have three button cells in series, and one of them dies, will the whole circuit still function at a lower voltage or will it stop flowing?

If I wire three button cell batteries in series, their voltages should be summed. Now, if a battery dies, let's say BAT3 for the sake of example, will the circuit operate at 6V or will it stop working? I would assume, due to the way series circuits are defined. that it would stop functioning, but then I realize that a battery is conductive, making me think that current would still flow, just at a lower voltage.

Which scenario would happen? I've provided a simple circuit diagram below.

simulate this circuit – Schematic created using CircuitLab

It would depend on the failure mode of BAT3 - how it died. If it fails short-circuit (for example, due to whiskers shorting the cell), then the voltmeter will show 6V. If however it fails open-circuit (for example, cells are protected and safety activates), the voltmeter will show 0V. Or BAT3 might provide less than 3V due to internal higher-resistance discharge, so the voltmeter might show say 7V.
There are other failure modes too important in real circuit (for example, if BAT3 internal resistance rises heavily; it might still read 9V, but be unable to give enough current to power device you will put instead of voltmeter, etc).