Electrical scooter having an equalization circuit for charging multiple

Abstract

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.