Hi.

I have a scale that I use to measure food weights that, in my opinion, drains the batteries too fast.

I use it twice a day ... but every three days one of the two batteries discharges (it drops from 1.5V to 1.2 if I remember correctly) and this does not allow the display to light up (making it impossible to see the numbers).
I disassembled it (I can attach photos) and there are four small sensors (or load cells), one for each corner. Then there is the microcontroller soldered to the display. Maybe the display consumes too much power?

Is there any way to measure how much it consumes? ..to see if it consumes too much (maybe there is a short inside)

This question is useful in general in case of a something that drains too quickly.

 

Insert a resistor in series with the batteries. Try 10Ω to start with and measure the voltage across it.
You didn't say what sort of batteries is uses, but there is usually a wire soldered to battery contacts that can be temporarily removed and the resistor inserted.

Are you remembering to turn it off after you have finished with it? Seems like a daft question, but I had a similar situation, and realised that the backlight turns off after a few seconds but the scale remains active and consuming power for minutes afterwards.

 

Get a new scale. I have a kitchen scale that runs on 2 x AA and the batteries last for years. Ii turns itself off after a minute or so of disuse.

 

You didn't say what sort of batteries is uses, but there is usually a wire soldered to battery contacts that can be temporarily removed and the resistor inserted.

exactly

 

Try 10Ω to start with and measure the voltage across it.

so I am indirectly measuring the current it draws during operation, right?
I will try it and update you.

What current values should I expect?

 

Get a new scale. I have a kitchen scale that runs on 2 x AA and the batteries last for years. Ii turns itself off after a minute or so of disuse.

definitely, I've already bought another

 

What current values should I expect?

depends on what is uses for the backlight - that will take more current than anything else.

 

I'd recommend getting a scale that doesn't have a backlight -- you shouldn't need one when you are standing in a kitchen weighing food. Backlights tend to draw a disproportionate amount of energy compared to the actual scale operation.

A decent scale should last months, if not years, on a set of batteries. My first electronic food scale didn't even let you replace the battery, which lasted over ten years. I tried to get into it to replace it when it finally died, but destroyed the scale in the process. The scale that I bought to replace it has now been in use for nearly six years and it on it's second set of 2xAAA batteries. It's a Taylor brand and I've been quite happy with it. It generally provides repeatable measurements consistent with its 2 g resolution.

 

Probably the scale drains the batteries because it does not switch off when it is not being used. That has been my experience. So adding a switch to break the battery circuit when no using the scale would solve the problem.