I have been using standard alkeline 9V batteries to power some of my gear, especially my DPA MMA6000 preamp. Over the years I have used a few different brands, usually getting about 20 hours on the MMA6000 (with powering of DPA4060 mics) before the green blinking light turns red, which is generally a sign that I have about 3-4 hours left before it goes dead. Recently I picked up a lot of Rayovac "Heavy Duty" 9Vs with a 5/15 use-by date. I noticed I was getting more like only 10 hours before I got the red light, last night the problem got to me, and I decided to see if the red-light warning time was still 3-4 hours (I always change out as soon as I see the red light to avoid losing anything). The red light blinking MMA6000 ran overnight for over 9 hours before I shut it down. When the red light starts blinking, my battery tester shows one or zero (of five) indicator lights, so it thinks the battery is shot just like the MMA6000 sensor.
Do "heavy duty" cells have some kind of different chemistry and see a voltage decline earlier? Since I want to dump the 9V cell as soon as the warning light appears, putting most of the cell's life during a warning period is not optimal for me. Is this just a bad batch? Has anyone seen anything similar?
Jeff