Greetings everyone!
I will start by saying that i'm a newbie and i'm just starting to learn so please don't be shocked if i say something that makes no sense. Also, as you might have seen, my english isn't great either.
Well, some weeks ago i bought a fake chinese Arduino data-logger, pretty much a clone of the adafruit one (
https://learn.adafruit.com/assets/9094 the original revision, not the B one). It works great, the problem is that the RTC battery only lasts a couple of days if the shield is disconnected from power.
I remember measuring the current from the coin cell at the time when the device was disconnected and the multimeter actually measured a pretty high value that according to a quick calculation would give approximate 2 days (but since my multimeter is garbage, i just thought it was giving a wrong value). Another thing i noticed was that when the shield was off and not attached to the arduino, the power LED on the shield was actually glowing very faintly and it would turn off when i inserted the SD card.
Anyway, i had two busy weeks and had to put it aside. Today, i took some time to play with it and sure enough the battery is flat.
I don't consider myself good enough to make this kinds of statements but as far as i can tell, the RTC part of this shield is connected exactly like the adafruit one.
I tracked the traces, checked continuity between different pins/components and measured some voltages. I'm feeding 3.3V from another arduino to the batt pads because i don't have another fresh battery.. Here is what i found:
The positive pad from the battery only goes only place : the VBAT pin on the DS1307 RTC
Voltage between battery pads: 3.27V
Voltage between GND and 5V: 1.47V (This pretty much means that the power LED, the 3.3Volts Regulator, the SD card and every single sensor i have connected are receiving that voltage (which is also going back to the arduino) that seems to be "leaking" through the VCC pin on the RTC).
Checking some reviews on amazon on this shield shows that more people have this problem but i also remember seeing someone complaining and he had an adafruit one.
Here is a close-up of the RTC:
Apart from this, everything works fine.
Any kind of help would be welcome, thanks!