2032 lithium cell charger with reverse polarity test

Published on 2024-01-19 | Archived on 2024-01-22

These USB powered chargers are only suitable for charging the LIR2032 rechargeable versions of the lithium button cells. Do not put a non rechargeable cell into them.

Note that the rechargeable cells are not suitable for all devices intended for a CR2032 non-rechargeable cell. Instead of providing a fairly consistent 3V for the full discharge the rechargeable cells start at 4.2V and reduce progressively to 3V during the discharge.

The charge current is about 15mA, which is well within the sensible range for these cells. The strange bypass resistor is odd, so I'd suggest not leaving cells in the charger continuously, although the leakage is small at around 6uA.

The chip seems to have various protective functions for the inevitable time that a cell gets put in backwards.

There is no facility for indicating to "intelligent" USB chargers that the device needs power. If it doesn't light with a fancy charger try a different one.

The little flashing supercomputer badges came from Mouse's Etsy shop. He hand makes them:-
www.etsy.com/shop/Flashything

The charger came from Temu:-
www.temu.com/goods.html?_bg_fs=1&goods_id=60109952…

The cells came from eBay a while ago.


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