I hate them! If I’m aware that a product uses them I try to find a similar product that doesn’t. This is a highly unscientific rant. Totally based on my own opinion based on my lifelong experience using them. They are relatively expensive, they are often awkward to install.
Why the rant? Because I just found a missing electronics meter, that was ruined because the 9-volt battery leaked and one of the posts totally deteriorated, to the point where I wouldn’t be able to replace the battery, because of it. Now that could happen to any battery. However in the case of a AA battery often there is still a nub remaining to provide some contact. Because of the length of time it has been missing…to some degree I expected it. So this rant isn’t so much to do with it leaking, but more to the fact as the necessity of this battery. Why is a 9-volt battery required for a device that is mostly off? You turn on every now and then for a brief test. Certain devices seem to require them. I think most of my old answering machines used them to provide backup memory protection, also electric clocks for the same reason. I think smoke alarms also often use them…and you are warned to replace them every year. If my memory is right…a lot of toys required them,
Why could my old CD player that had to spin a motor to spin the CD and had a LED display, run on 2 AA (rated at 1.5volts each) batteries. I admit it couldn’t run very long, but the operating requirements seemed pretty steep. Why can my analog clock that has to turn the hands run 2+ years, using 1 AA battery…last so long? The minute hand has to advance 1440 times a day. It also has a second hand that has to move 86,400 a day. That’s 2,635,200 movements a month. But an electronic meter that only has a LED display and is used very infrequently…in my case…require 9-volts? Is there anything that my electronics meter using a 9-volt battery could do that 2 AA batteries (3 volts) couldn’t do?
Is there a 9-volt consortium, convincing companies to use them?
In all likelihood there is some reason. Perhaps 99.999% of the parts could work fine with 2 AA batteries, but one specialty part requires a higher voltage for some reason? On the other hand I took out another digital multimeter I bought a few years ago, to replace the one I just found, that has largely been sitting for a few years. I didn’t have to open it up because I found a YouTube review video of the exact model and it showed installing 2 AA batteries. The review was very positive.