Power management control system for battery powered devices

• US 5,519,261 A
• Filed: 04/06/1995
• Issued: 05/21/1996
• Est. Priority Date: 02/14/1991
• Status: Expired due to Term

• Current Assignee: Dell USA LP (Dell Technologies Inc.)
• Original Assignee: Dell USA LP (Dell Technologies Inc.)
• Inventors: Stewart, Gregory N.
• Primary Examiner(s): Fleming, Fritz M.
• Application Number:
  US08/421,305
• Time in Patent Office: 411 Days
• Field of Search: 307/64-66, 307/70, 307/10.7, 307/85-87, 307/132 E, 307/132 EA, 307/150, 361/166, 361/167
• US Class Current: 307/87
• CPC Class Codes: H02J 7/34 Parallel operation in networks using both storage and other dc sources, e.g. providing buffering H02J7/14 takes precedence

Abstract

Method and apparatus for increasing the amount of power that may be extracted from a plurality of parallel connected battery banks by periodically effecting a switching between the banks for operative coupling to the power supply of an electronic or electrical device. The apparatus comprises at least two battery banks, a switching means, a microcontroller and a battery powered load. Upon each expiration of a predetermined time interval, the microcontroller monitors the voltage of the battery banks to determine which of the banks has the highest voltage. The microcontroller then positions the switch so that the bank with the highest voltage is coupled to the power supply of the load. In another embodiment, switching occurs upon a determination that the active bank has reached a specified power output.

Claims

1. Apparatus for electrically switching between a plurality of parallel connected battery sources to power a load to enable an even discharge among said sources, the apparatus comprising:

switch means for alternatively electrically connecting or disconnecting each of said sources with said load responsive to a control signal, wherein one of said sources is connected to said load and the remaining ones of said sources are disconnected and inactive;

means connected to said sources for reading the voltage and amperage of said one of said sources connected to said load; and

control means connected to said switch means and to said reading means for periodically computing an instantaneous power value from said read voltage and amperage of said one of said sources connected to said load, for accumulating said periodically computed values, for comparing said accumulated value with a predetermined power value, and for providing a control signal to said switch means to electrically disconnect said one of said sources connected to said load and to electrically connect another one of said sources to said load when said accumulated value exceeds said predetermined power value, wherein said accumulated value represents a cumulative amount of power output by said one of said sources since said one of said sources was last disconnected and inactive and said predetermined power value is substantially less than the total power available from said one of said sources when said one of said sources is fully charged.

2. A method of controlling the electrical connection of each of a plurality of battery sources to power a load, the method comprising the steps of:

connecting one of said sources to said load;

reading the voltage and the amperage of said one of said sources connected to said load;

periodically computing an instantaneous power value from the respective voltages and amperages of said one of said sources electrically connected to the load;

accumulating said instantaneous power values to determine an accumulated power value;

comparing said accumulated power value with a predetermined power value, wherein accumulated power value represents a cumulative amount of power output by said one of said sources since said one of said sources was last disconnected and inactive and said predetermined power value is substantially less than the total power available from said one of said sources when said one of said sources is fully charged; and

electrically disconnecting said source connected to said load and connecting another one of said sources to said load, when said accumulated power value exceeds said predetermined power value, to enable an even discharge among said sources.

3. The method of claim 2 wherein said step of computing an instantaneous power value is performed once each second.