Effect of Battery String Inductance on Load Circuit Noise and Battery Charger Filter Performance

The effects of battery and distribution impedance on battery charger dc output noise is considered for various capacitor and inductor output filters. The importance of distribution bus and "battery loop" inductance is demonstrated and it is shown that the improved filtering expected from larger ampere-hour batteries may not be realized. Methods to calculate distribution inductance and battery impedance from manufacturers data and physical layout are given and compared to experimental results. Actual charger and battery C message weighted noise is predicted with good accuracy from ac frequency response and transient analysis simulation models.