From: charlie@xxx.net
On Sat, 06 Dec 2025 16:27:19 -0500, legg wrote as
underneath :
>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 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.
>
A thing I found is that the permanantly attached buck or boost regulator
in these batteries, (PP9 EBL with USB boost reg. in my case) can drain
the LiPo well below ideal V either in storage or instruments that are
only used occasionally, so worth keeping an eye on that type of very
life shortening behaviour!
I would suspect the 1.5v might follow the samee pattern except with a
buck reg.. C+
--- SoupGate-Win32 v1.05
* Origin: you cannot sedate... all the things you hate (1:229/2)
|
