abating effect of battery

[Bhuvanesh123]

why at the end of battery period.it giving 1 volt instead of it actually 1.5 volt.why the internal resistance increasing and voltage decreasing at end time of battery.thank you in advance

 

[Audioguru]

Maybe you are asking about a throw away battery like alkaline, not a rechargeable battery?
When you say, "end of battery period" do you mean when the battery is worn out and is dead?

When a throw away battery is used then its chemicals get used up which increases its internal resistance. With the internal resistance in series with the load resistance then there is a voltage divider that reduces the output voltage. The used up chemicals cannot produce 1.5V anymore even with no load.

After powering a smoke detector for one year but not making a sound, its 9V battery measures 8V or more but its voltage drops very low if it has a load that draws 10mA or more.