a voltage resistors r 42 and r 136 preferably comprise a current to voltage converter the voltage developed across resistor r 136 is proportional to the leakage current from pins m n p r operational amplifier u 104 preferably is configured as a high input impedance voltage follower the output signal of which is labeled float 0 thus float 0 is a voltage that is indicative of any leakage current that may happen to develop on the battery connector j 101 to accurately control charging current it is important to determine the battery voltage at the battery terminals and not at the charger end of the cable that connects the battery to the charger the voltage usually differs from one end of the battery cable to the other because of the inherent impedance of the battery cables which causes a voltage drop along the cable conventional battery chargers have solved this problem by including separate u201c sense u201d lines from the battery terminals to a high impedance voltage monitor circuit in the charger these sense lines are in addition to the battery cable that provides charging current to the battery because the impedance of the voltage monitor is relatively high negligible current flows through.