Solved - See post #7 below
Have a project with a Pro Mini 5V, 1602 LCD I2c, and DS3231 I2c.
I am trying to get a low power sleep following Nick's and others power saving suggestions.
I have removed power led and regulator from pro mini.
I have removed power led and charge circuit on DS3231 and replaced rechargeable battery with CR2032
I am powering both LCD and DS3231 through a digital output pin.
sleep_mode = SLEEP_MODE_PWR_DOWN ADC disabled BOD disabled
wake through pin interupt
Everything is working well but I cannot get below 228µA when in sleep mode.
I have narrowed the culprit down to the DS3231 seeming to draw 200+µA through the SDA/SCL lines. When I disconnect the SDA/SCL from the DS3231 (but not the 1602 LCD) the power use drops below the 1µA level ;D . I can see power use drop 100+µA per line as I disconnect each one.
I just need to know what is happening and how to fix it. I assume it is something to do with the DS3231 and not the I2c on the pro Mini as the 1602 LCD does not affect it in the same way.
Thanks for looking.
My first post and I am a noob to Arduino so apologies if I have not included enough info or posted in wrong section.