[Andy Terry]

Andy Terry asked the Naked Scientists:
   
When some of my battery powered items run out of power, I naturally replace the batteries with new ones.

If I test each "dead" battery with a meter I notice that some will be completely drained whereas others are still fully operational and can be re-used.

Obviously this only happens with items requiring more than one battery wired in series.

Why is this?

What do you think?

[gora]

This is because when they are in series one dead/faulty battery is enough to break the circuit link and hence make the device go down.