Battery charging system

A method of regulating the charging of first and second series-connected batteries, the method comprising:

• operating in a normal mode in which voltages across the first and second batteries are regulated by first and second voltage regulation circuits connected in parallel with the first and second batteries, respectively, wherein the first and second voltage regulation circuits are non-conductive when the voltage across the first and second batteries, respectively, is less than a threshold value and conductive when the voltage across the first and second batteries, respectively, is greater than a threshold value;
• monitoring the voltage across the first battery and the voltage across the second battery;
• and
• operating in a protection mode in response to the monitored voltage across either the first or second battery exceeding a second threshold value, wherein output voltage of a battery charger is reduced in the protection mode.

A battery charging regulation and protection system for use with first and second series-connected batteries, the battery charging system comprising:

• a first voltage regulation circuit connected in parallel with the first battery that provides a first conductive current path that bypasses the first battery in response to a voltage across the first battery exceeding a threshold value;
• a second voltage regulation circuit connected in parallel with the second battery that provides a second conductive current path that bypasses the second battery in response to a voltage across the second battery exceeding a threshold value;
• and
• a battery charger controller connected to monitor voltage across the first battery and voltage across the second battery, wherein the battery charger controller detects a fault in the first voltage regulation circuit and/or the second voltage regulation circuit if the voltage monitored across the first battery and/or the voltage monitored across the second battery exceeds a second threshold value.