i am wondering is there any battery tester for NiMh battery? like for 2500mah or 2000mah... cos sometimes i charged the batteries but never use, but not sure if the batteries have discharged or full, den if 2500 have discharged to 1800 or lower, does it still show full energy, or will a battery tester still know the diff is a 2500 and show accurately the amount of power left?