One word y'all:
NOISE. It's the elephant in the room that few want to address. It's a word that will make any experienced electronics professional cringe - especially me.
Here's a quote from a 'review' of some Xtars:
EDIT: I neglected to include acknowlegment of and thanx to 'sammyshp' for this quote:
************************************************************************************
"Another device I used for testing is a radio clock with external temperature sensors. At about 1.3V the display starts to fade, at 1.2V it is almost unreadable. And that's the normal voltage of NiMH batteries. With the XTAR batteries the contrast is always perfect. At the end of discharge the display would be unreadable, but the alarm would still work.
But there is a problem: The clock signal is only received when I bring the clock outside and the temperature sensors are not received at all! There must be some kind of interference with the batteries.
When checking the noise of the voltage with an oscilloscope at different loads it becomes obvious. I guess there was not enough room for proper filtering, but this limits the use of the batteries. It is likely they will cause trouble when used in something that receives radio signals."
View attachment 61438
"I tested the discharge at currents ranging from 600mA to 1600mA. Even at the highest load they provide 1.5V, but they will also heat up significantly. My test was open on the bench, so it will become a much bigger problem enclosed in devices."
***************************************************************************************************
Here's a quote from a user of a Tenavolt variant:
"Yeh, I got a clock/thermometer that takes 3 AAAs. 1 is for something and 2 are for something else. Forgot which is for the backlight-only and which is for the digital innards.
Either way, the backlight always works fine, as it's not picky, but when I switched from alkaleaks to… think they were Tenavolts… the buttons to set the clock, etc., just plain wouldn't work. It kept time, starting from 12:00:00 of course, but you couldn't set the time, switch from C/F or F/C, nuttin'."
****************************************************************************************************
Keep in mind that noise like this is not simply an electrical component of the 1.5V "DC" output of the cell, potentially affecting the device they're powering, but there are almost certainly electromagnetically-radiated components as well. I have seen no published specs on any of this from any manufacturer of cells of this type. I have seen no user precautions or guidance provided on any of this either. I've also seen no tests using a 'field strength meter' or spectrum analyzer yet.
One of the most problematic aspects of 'noise issues' is that they are frequently not binary / black-and-white issues, but such issues are often marginal, variable, or intermittent as well. Something may appear to work today, but be degraded or fail to work completely the next, depending on variable factors which may not be evident. Additionally, if it's interfering with an RF AV (or other) equipment remote (just for example since there's one sitting here), or increasing the BER (bit error rate) on a wi-fi or BT connection in the vicinity, will you know it? How much do you depend on RF devices / products in your environment? Are you sure you want to sign up for worrying about all this at this point in time?
These are things I consider, and everyone has to make their own subjective decision about.