Arduino Nano V3 LowPower not possible

Hey,

i am totally confused about low power mechanism on arduino nano.

i am using arduino nano v3 with atmega328p from china. to reduce power consumption i removed USB chip and voltage regulator. power comes from 5V external power supply and is connected to 5V and GND pins.

i am using this library: https://github.com/rocketscream/Low-Power

source code is easy (example from rocketscream):

// **** INCLUDES *****
#include "LowPower.h"

void setup()
{
    // No setup is required for this library
}

void loop() 
{
    // Enter power down state for 8 s with ADC and BOD module disabled
    LowPower.powerDown(SLEEP_8S, ADC_OFF, BOD_OFF);  
    
    // Do something here
    // Example: Read sensor, data logging, data transmission.
}

i program the modified board via ISP, using another nano as ISP programmer.

when the code is executed, i would expect the current drawn by the board to go down to several microamperes. what really happens that it is only going down from 40 mA to 20 mA!!

What am i doing wrong? are there some cheap ATMEGA328P chips or even copies from china that do not support powerDown? seems like that as the code is not the problem, i also tried jeelib library - same behaviour.

could anyone give me an idea what to do? thanks

Nano has pn/off led?

sterretje: Nano has pn/off led?

what do you mean?

The nano has a power led (I just checked the schematc. Did you remove that as well (you did not mention it)?

As I have never used power saving, I can not help with code.

The 40mA is about the consumption of a Nano board without anything disconnected - I’d first suspect you have not disconnected things properly or have created a solder bridge in the process .