1.5V / 1000Ω = 1.5mA

Reading 3 on 25A FSD means 3A.
Your 1.5V AA battery is putting out 3A to the meter, only 1.5mA through a 1kΩ resistor in parallel.

You are right, my bad, thank you!

 

So it would appear that this is a 15mA FSD meter and it requires an external shunt in order to display 25A FSD.
1.5mA / 15mA = 1 / 10
25 / 10 = 2.5 which is close enough to 3 which is what you observed.

Use a variable resistor or a voltage divider as suggested by @AlberHall.

 

It appears to be a moving coil meter, with a full scale deflection of 15mA or 60mV, requiring a 25A 60mV external shunt.

It may be tested using an analogue multimeter, set to measure Ohms, with the probe current in the selected range much less than 15mA (multiplier / probe current marked on the multimeter).

Regards,

Nandu.

Thinking about it I do believe you may have a point. Twenty-Five amp would require a large shunt to be internal to the meter body.

Ron