I think I left a post about me using this module previously, but I cant find it, so i decided to leave a new one.
First, background info.
On my photobooth I use a RPi 2.
Since I have the option of stamping date and time on each photo, I needed a way to have the date and time on the RPi be correct between power downs.
So I bought a cheap DS3231 Real Time Clock Module from ebay or amazon.
It didnt have a lot of info on it but it was pretty easy to install and setup. I wont get into that here.
It had been put up for over a year, I decided to drag it out and test it. Guess what. The date and time was December 31 1999 and 00:00.
The date and time auto corrected a few seconds later when the RPi connected to the internet. But when I disconnected from internet date/time reset to 1999 after RPi reboot.
Since I made this to be carried to parties, get togethers, or whatever, I knew an internet connection may not always be available, so keeping correct date and time was important.
From info I gathered on web, the battery on the module is rechargeable. So I left photobooth on all night and tried next morning. Still no correct date/time.
I unplugged the module and measured voltage on the battery. It was around 0.25 volts. So it didnt charge in more than 10 hours. I figured battery was bad.
I removed the battery and soldered two test leads in the place of it.
Here is a pic:
I then placed a diode in series and temporarily wired it to a CR2023 coin battery (I used the diode to prevent any current trying to charge the battery, since the CR2023 is not rechargeable):
The clock worked great while setup like this.
The battery had two clips that was spot welded to it, these soldered onto the circuit board. I removed these so i could see the battery number:
This battery is a CR927, and according to the specs, it is not rechargeable. So that bit of info about this module is wrong. The specs also say the battery should last 7 to 10 years, so I either got a defective battery or one that had been on a shelf in china for many years.
I wish they had a battery holder on this module so I could just change out the battery when it dies. (There are some models that do have this holder.)
So my plans are to acquire a coin cell battery holder and install it. And go with a more common coin cell 3 v battery.
Hope this helps anyone else who decides to use one of this clock modules.