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Topic: ZS-042 DS3231 RTC module (Read 693 times) previous topic - next topic

dunio

Nov 11, 2014, 11:41 am Last Edit: Nov 11, 2014, 08:36 pm by dunio
Hi there,

I recently got my DS3231 module labeled ZS-042 off of ebay and it came with a CR2032 3V battery.

The module works at 3.3V and also 5V however after some days of usage at 5V I noticed that the battery has become quite "thick". A quick check with the multimeter confirms that the module force-charges the battery with VCC! Not quite nice. Here a pic:


So you should at least power this module only at 3.3V, even then, question to the experts: is it save to "charge" a 3V CR2032 at 3.3V continuously without it breaking after some time? 2nd question: is it ok to charge a LIR2032 at 5V?

Other than that the module works quite well with the time library :)

Edit: corrected 3202<>2032 messup

Charging the LIR2032 at 5V is not such a good idea, it will shorten the life of the battery. Charging a CR2032 is a BAD idea. Just cut the PCB trace between the diode and the 201 resistor and use a CR2032. Check the attached image "trace_cut.png"
A CR2032 will last more than 10 years

dunio

#2
Nov 11, 2014, 08:38 pm Last Edit: Nov 12, 2014, 12:57 am by dunio
Ah, ic, but as a LIR2032 is 3.6V, a VCC of 3.3V would be not be sufficient to charge it. So this thing is a complete fail?

I think it would be best to use a supercap instead of the CR/LIR battery, something like this:

spelle

Just received this module myself and very happy that I found this thread before wiring up the circuit.
Maybe the best solution, with a CR2032 as battery backup, is simply to desolder the diode. Then VCC is decoupled from the battery and pin 13 on DS3231.

VanJ

#4
Dec 09, 2014, 01:18 pm Last Edit: Dec 09, 2014, 02:38 pm by VanJ
Hi there,

I recently got my DS3231 module labeled ZS-042 off of ebay and it came with a CR2032 3V battery.

The module works at 3.3V and also 5V however after some days of usage at 5V I noticed that the battery has become quite "thick". A quick check with the multimeter confirms that the module force-charges the battery with VCC! Not quite nice. Here a pic:


So you should at least power this module only at 3.3V, even then, question to the experts: is it save to "charge" a 3V CR2032 at 3.3V continuously without it breaking after some time? 2nd question: is it ok to charge a LIR2032 at 5V?

Other than that the module works quite well with the time library :)

Edit: corrected 3202<>2032 messup
I don't understand, how the charging current can be 5V at 5V VCC, when there is a diode in the charging circuit. I thought it should be Vcc - 0.7V (voltage drop on the diode) = 4,3V, or not? That would be just a bit above the standard charging current (4.2V) for the Li(ion,pol) batteries. And the resistor in series should drop the charging voltage also, or not?

crnv

I received two ZS-042 modules from ebay today which look like the one shown in the picture. Since I found this thread while looking for a library for this module, I would like to clarify something:

I cannot confirm that the battery is charged at VCC. I measured 4.2V after the diode when attaching the module to a VCC of 5V. So it is OK to use the module at 5V if a LIR2032 is used.

However, it is a bad idea to use the module with a CR2032, unless you cut the PCP trace as suggested by shahidali55.


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