Detect LIR2032 vs CR2032 Battery In Charge Circuit

[hal9001]

I want to use a TP4056  chip to charge a LIR2032 battery. The battery can be replaced since its in a battery holder. Is there a way to detect and not charge the battery if a CR2032 is replaced instead of LIR2032?


Cheers!

[ArdWar]

Idk if it always holds true universally but CR2032 won't even allow you to charge them. Apply 4V across them and they'll probably only let ~40uA through. I guess you can detect the charge current and bail out if it's too low. You probably want to cut off LIR charging anyway if it goes below ~100uA.
The problem is that this is not a guaranteed behavior.

Theoretically you can check their voltage. A properly maintained LIR2032 should not go below 3V while a CR2032 won't go above 3V (save for brand new one with zero lead).
The problem is that a deeply discharged LIR2032 can go below 3V too and still OK to charge.

[tszaboo]

This is where a sticker, user guide, and silicon sealant are a good candidate to solve a problem, instead of some electronics.

[Peabody]

The popular SZ042 module for the DS3231 RTC has a 2032 holder onboard, and it has a "charging" circuit consisting of a 200R resistor and a 1N4148 diode in series.  This is a holdover from the time when the holder was populated with an LIR2032.  When powered from 5V, this circuit would apply about 4.4V to a CR2032 continuously.  Many thousands of these modules have been sold with CR2032s, and you don't hear of batteries blowing up.  I don't know how well the charging circuit actually works for an LIR2032.  It doesn't follow the CC/CV algorithm, and never terminates, so it definitely doesn't follow the rules.  But I don't know if that matters.

But the question in my mind is what the TP4056 would do when attempting to charge a CR2032.  If it applies full charging current, would voltage ever reach 4.2V?  How much current would actually flow?  If almost none did, would it terminate?  It seems to me that you should give this a try.  There may be no need to detect a CR if the TP4056 would refuse to charge it in the first place.

Don't forget to replace the TP4056's default charge current setting resistor.  I read that 33K (for 35mA) is the right one for an LIR2032.