Electrical scooter having an equalization circuit for charging multiple batteries

• US 5,965,996 A
• Filed: 12/11/1997
• Issued: 10/12/1999
• Est. Priority Date: 12/11/1997
• Status: Expired due to Term

• Current Assignee: Vectrix International Limited (Gold Peak Industries Limited)
• Original Assignee: Vectrix Corporation (Vectrix Holdings Ltd.)
• Inventors: Szabo, Andrew N., Dobrowski, Russell G., Arledge, Arthur L., Hughes, Peter S.
• Primary Examiner(s): Wong, Peter S.
• Assistant Examiner(s): LUK, LAWRENCE W
• Application Number:
  US08/989,174
• Time in Patent Office: 670 Days
• Field of Search: 320/122, 320/116, 320/126, 320/118, 320/148, 320/149
• US Class Current: 320/116
• CPC Class Codes: B60L 2200/12 Bikes
• CPC Class Codes: B60L 2240/545 Temperature
• CPC Class Codes: B60L 2240/547 Voltage
• CPC Class Codes: B60L 2240/549 Current
• CPC Class Codes: B60L 58/22 Balancing the charge of battery modules
• CPC Class Codes: H02J 7/0016 using shunting, discharge or bypass circuits
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries

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.

Claims

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 having

a 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; and

a 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; and

a 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; and

a 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, and

when the controller is in the first mode, the controller intermittently provides said external signal.

2. The electric scooter of claim 1, wherein said controller provides said external signal only during periods in which there is no current draw from said series connected batteries.

3. 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 having

a 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; and

a 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; and

a 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; and

a 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, and

when the controller is in the second mode, the controller continuously provides said external signal.

4. 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 having

a 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; and

a 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; and

a 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;

a 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; and

a power relay connected to said controller and configured to selectively connect said series connected batteries to a motor controller associated with a motor of said scooter, upon receipt of an activation signal from said controller,

said activation signal being provided upon starting the scooter, only if said controller receives no first signal from said first logic circuit after providing said external signal to detect a low voltage condition in said series connected batteries.