Mundane question, but I betcha this one has caught somebody else besides me: batteries that work, sort of, but give less than optimal audio.
How do you test your oddball, tiny mic batteries so you don't wind up using them past their time? I've just experienced the oddest thing: batteries that failed ever so subtly that they worked, sort of, even when they tested dead. So I don't know how long I was getting audio that was even more subtly less than it could have been.
I had been using a pair of Trams with their power supplies and A76/LR44 batteries, when the audio suddenly seemed a little fuzzy. You could still get usable interview sound -- it sounded like background ambience that could easily be EQed out in post. I was shooting in a high-tech facility with engineers everywhere, and one of them pulled out a meter and told me that the batteries tested dead. I was surprised, as I always pull the mic batteries when they aren't in use, and the audio was definitely usable though flawed.
I understand that battery testing is only meaningful when the tester puts the battery under "load." I'd appreciate a recommendation for a good device so that I don't again use a battery that works "sort of."
Use any small meter that has an "Amps" high enough to handle, say 10 DC amps.
Then just touch the leads (plus and minus) to those of the battery.
The meter will nearly "short" the battery when the leads are connected (putting it under a very high "load"), so only test JUST long enough (a second or two) to get a reading (which will steadily FALL, if you leave the leads across the battery too long.)
To know what a "good" battery should read, test a couple of known NEW batteries and note their readings.
I, too, have experienced the "fade" of the little hearing aid batteries in my Trams.
But it takes a long (LONG) time for the Tram to "drain" even the lowest=cost new batteries I install.
Your method may require a degree of physical dexterity that I may not be able to muster. I was hoping to find a tester that I could simply slide the battery into -- and something compact and versatile enough that I could include it in one of my travel cases, and test other batteries as well.
How seriously do you take the concept of "testing under load?"