Ammeter

The invention discloses an ammeter which completely gets rid of a scheme in which a rechargeable battery is taken as a backup power supply and only takes an electrochemical capacitor as the backup power supply. According to the ammeter, a direct-current boosting and voltage-stabilizing module is utilized so that the capacitor of the backup power supply can provide a relatively large amount of electric energy; furthermore, on the basis, a voltage comparison module and a control module are additionally arranged; threshold value voltage which is higher than the lowest working voltage of a working circuit and is lower than power supply voltage in the normal power supply process is set; the charging and the power supply of a power accumulation device can be automatically switched.