Hi Henk
Thanks for the PM. Here is a simple circuit I use that will not allow the PP3 to discharge below 7.5V. Takes a few hours to flatten completely. Please see attachment.
The same circuit can be added as battery protection inside the Microphone by substituting the 82R resistor with the Microphone power + and - leads. Too simple to work...well it doe's. Believe me
Dropout Voltage across the BC327-40 Collector Emitter is around 100mV to 200mV for everything down to around 8.1V., when the little PP3 is basically battling anyway.
Little PP3's don't like being charged at 1C. They also don't like to be discharged at 1C.
A good balance is 0.5C for long life.
They are my Babies.....and I have yet to loose one
Just realized......I sound like a Woman
. Women are Wonderful...and good and all and some carry batteries...
Out of here before I get into trouble.....again...My mind never stops working. Unlike me
Regards,
tvtech
Edit: Note Q1 is BC327-40 and R3 is 82R 5W.