From: legg@nospam.magma.ca   
      
   On Sun, 07 Dec 2025 05:26:44 GMT, Jan Panteltje    
   wrote:   
      
   >>legg wrote:   
   >>>Rechargeable 1.5V lithium batteries are complicated animals.   
   >>Not a battery, as such, so don't rely on standard battery   
   >>chemistry descriptions to cover them.   
   >   
   >   
   >   
   >>From tested behaviour:   
   >>   
   >>There's a real 3.7V lithium cell inside there somewhere, with   
   >>a charging voltage of over 4V on the battery terminals.Open   
   >>circuit when charge is terminated internally.   
   >>   
   >>When it's not being charged, a switching regulator takes over   
   >>to produce 1.5V on the same terminals, drawing from the   
   >>lithium cell. This buck regulator is unstable when the battery   
   >>is not being used, so the battery terminal voltage jumps around   
   >>if you try to simply measure it.   
   >   
   >I use 'Eneloop' 1.2 V rechargable AA and AAA batteries.   
   >Zero selfdischarge, lasts forever, .   
   >And safer :-)   
   > 800 mAh for AAA in my flashlights temperature sensor, several remotes...   
   >1900 mAh for AA  in my Tecsun radio, drone remote and gamma spectrometer   
   >For the radio (multiband) it needs to be noise free   
   >I have all sorts of LiPo and those have all sorts of limitations and problems.   
   >   
   >   
   >With all those converters there must also be an efficiency factor  80% ?   
      
   I think it comes out in the wash, considering the energy density   
   improvement of the mockingbird's chemistry.   
   >   
   >   
   >>I wonder what this does to devices that count on the low noise   
   >>usually produced by simpler standard cells. Guess I'll find out   
   >>the hard way. Loaded, the voltage will stabilize, but then you've   
   >>got normal switching ripple and, supposedly, emc issues.   
   >>   
   >>Nothing in the literature (?)- it's still the wild west as far as   
   >>battery products go, in the far east. Currently less than   
   >>US$1.50 per in low volume retail.   
   >>   
   >>I lucked into a bunch of rechargeable 9V (PP3) lithiums the other   
   >>day - furnished with a micro-usb port for charging. Same basic   
   >>idea, but with a boost regulator supplying the terminal voltage.   
   >>   
   >>RL   
   >   
   >I have a programmable powersupply to charge almost any type of battery.   
      
   - if you can actually get at the real battery terminals.   
      
   - with these, 'all' you seem to need is a USB source.   
      
   Who would have thought that USB would turn out to be the   
   most widely used consumer power interface . . .   
      
   RL   
      
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