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An electric scooter employs an equalization circuit for charging a plurality of series connected batteries used to power the scooter. The equalization circuit has a number of cell circuits, each connected across the terminals of a corresponding battery. Each cell circuit includes two voltage detecto

An electric scooter employs an equalization circuit for charging a plurality of series connected batteries used to power the scooter. The equalization circuit has a number of cell circuits, each connected across the terminals of a corresponding battery. Each cell circuit includes two voltage detectors, a first implemented as a modular voltage monitor for detecting a low voltage across the battery terminals, and the second implemented as a Zener diode to detect a high voltage across the battery terminals. Both voltage monitors are enabled by an optocoupler switch. When the switch is turned on and either a low or a high voltage condition is detected, the cell circuit outputs a signal reflective of this condition through a second optocoupler. During a constant current charging phase, a high voltage condition causes the cell circuit to cause a portion of the charging current to bypass that battery, thus achieving equalization. A controller, which selectively enables the first optocoupler, also receives outputs from logic circuitry which tells whether any of batteries have low voltage and also whether the series connected batteries are fully charged. The scooter monitors the batteries for low voltage conditions during starting and also during quiescent states, i.e., low or no current draw, when it is being operated.

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[ What is claimed is:] [1.] An electric scooter comprising:a plurality of series connected batteries, each battery having a first and a second terminal and a battery voltage across said terminals;an equalization circuit arranged to distribute current among said plurality series connected batteries d

[ What is claimed is:] [1.] An electric scooter comprising:a plurality of series connected batteries, each battery having a first and a second terminal and a battery voltage across said terminals;an equalization circuit arranged to distribute current among said plurality series connected batteries during a constant current charging phase, said equalization circuit comprising:a plurality of cell circuits, each cell circuit being connected across the terminals of a corresponding one of said plurality of batteries, each cell circuit havinga first detector circuit arranged to detect a low voltage condition wherein the battery voltage is lower than a first predetermined value,a second detector circuit arranged to detect a high voltage condition wherein a detected voltage is higher than a second predetermined value, said second predetermined value being greater than said first predetermined value;a first switch arranged to enable both of said first and second detectors in response to an external signal;bypass circuitry arranged to bypass a charging current around the corresponding battery after detection of said high voltage condition; anda second switch arranged to output a status signal signifying detection of either a low voltage condition or existence of a current bypass condition wherein a current flowing through said bypass circuitry exceeds a predetermined amperage;a first logic circuit having an output providing a first signal when any one of said second switches outputs a status signal signifying a low voltage condition; anda second logic circuit having an output providing a second signal when all of said second switches output a status signal signifying existence of said current bypass condition; anda controller electrically connected to each of said first switches to selectively provide said external signal, wherein said controller provides said external signal in a first mode to detect a low voltage condition, when said scooter is being operated,said controller provides said external signal in a second mode to detect the existence of said current bypass condition, when said series-connected batteries of said scooter are being charged, andwhen the controller is in the first mode, the controller intermittently provides said external signal.