Quote: (Originally Posted by
wedivebc)

Does anone know what minimum voltage is accecptable when using 9v batteries? There must be some point where battery failure is imminent and should be changed.
My sense is that would be highly dependent on both the brand of battery and the type of chemistry (alkaline, lithium, other). The only hard numbers I can give you are with an alkaline Rayovac. I did a test with it running the primary. After 4 1/2 hours it read about 7.5 v no load and 7.1 or 7.2 load and was working normally. A long time (many months) later same battery had recovered to well over 8 v.
Ken