DS1307 rtc clock issue

Hi all

I have an issue with a Grove RTC clock connected to a Grove Shield on Arduino Uno.

I can set the clock via the official code, but after unplugging the board it always resets, here an example output:

Set time :
|10:35:35|12/15/2021 15TUE |
|10:35:35|12/15/2021 15
TUE |
|10:35:35|12/15/2021 15*TUE |

Upload some code to read time :
12/15/2021 10:35:44
12/15/2021 10:35:45
12/15/2021 10:35:46

Unplug / plug board :
RTC is NOT running!
1/1/2000 0:0:0
1/1/2000 0:0:0
1/1/2000 0:0:0
1/1/2000 0:0:0

The code used for reading the time is the following

#include <Wire.h>
#include "RTClib.h"

RTC_DS1307 RTC;

void setup () {
    Serial.begin(9600);
    Wire.begin();
    RTC.begin();
  // Check to see if the RTC is keeping time.  If it is, load the time from your computer.
  if (! RTC.isrunning()) {
    Serial.println("RTC is NOT running!");
    // This will reflect the time that your sketch was compiled
    // RTC.adjust(DateTime(__DATE__, __TIME__));
  }
}
void loop () {
    DateTime now = RTC.now(); 
    Serial.print(now.month(), DEC);
    Serial.print('/');
    Serial.print(now.day(), DEC);
    Serial.print('/');
    Serial.print(now.year(), DEC);
    Serial.print(' ');
    Serial.print(now.hour(), DEC);
    Serial.print(':');
    Serial.print(now.minute(), DEC);
    Serial.print(':');
    Serial.print(now.second(), DEC);
    Serial.println();    
    delay(1000);
}

I have tried with 2 RTC chips and 2 different batteries, what could be the reason for the RTC not storing the time?

thanks

are those "rechargeable batteries"?

no, Lithium 3V (CR1225)

Please try CR2032 and see if there is any improvement.

2032 doesn't fit in the slot, it is too big

Are you sure the battery is installed with the correct polarity? Can you post images of the module?

many DS1307 include a (quite crude) circuit for charging the battery. If it's a non chargeable one, that might/could create some issues (?)

The Grove RTC does not appear to have the dodgy charging circuit, so that's good. However, the published schematic does not match the board either, nor does the published PCB layout.

With the battery installed, you need to check the clock chip (U1) pin 3 for 3V to ground. It should be over 2V. If not, either the battery socket is not making contact with the battery or the board, or the trace is defective.

-fab

i realized that inadvertently the grove board was set to 3V, after switching to 5V it started working...spent few hours and did not check the easiest option, doh!