Short Backstory: As I am doing photography, I still have some old Nikon gear lying around, that I intend to reuse for tinkering or some "high-risk" shots, where damage of the gear i no big concern due to low value.
On ebay I sourced some 3rd party batteries for a decent price, that are of the old type (LiION, 7.4V nominal voltage =2 cells internal) and no digital coding, only a small internal PCB for charge control and balancing. (And reporting back on a 3rd terminal the charge status to cameras with respective contacts like the D200 etc.)
Sadly, out of 5 used batteries only 2 were showing 7.4V, the three remaining were dead from the outside- my DMM showed 0.0xx Volts.
I cracked one open, and the cells measured 2.5 and 2.8 Volts, so they were about deep discharged.
As they were not only intended for powering a camera, but also to power (as second usage) some breadboard power supplies for tinkering (and eliminating power supply ripple...) I also might de-solder the 18500 cells inside and use the cells separately.
I mean those el cheapo power converters that can be clipped onto a breadboard and with 7.5V-9V input voltage they will provide 3.3V and 5V output- perfect for some things I will do some work with- and with a battery there cannot be ripple from a SMPS...
Questions:
- How good are my chances to manually revive those 18500 cells?
- Any good Li/Ion charger that could be recommended for usage with 18500 and 18650 cells? (Preferrably below the 50 €€€ mark...)
- What about manual charging via lab power supply?
- Any tips where to get in germany some 18500 battery holders (preferrably in one piece, no separate clamps for soldering onto a PCB)?