Solid state safety jumper cables

• US 5,189,359 A
• Filed: 01/22/1991
• Issued: 02/23/1993
• Est. Priority Date: 01/22/1991
• Status: Expired due to Fees

• Current Assignee: US Department of Energy (Government of the United States of America)
• Original Assignee: James W. Kronberg
• Inventors: Kronberg, James W.
• Primary Examiner(s): Hickey, R. J.
• Application Number:
  US07/643,317
• Time in Patent Office: 763 Days
• Field of Search: 320/25, 320/26
• US Class Current: 320/103
• CPC Class Codes: H02J 7/0034 using reverse polarity correcting or protecting circuits mechanical means of polarity protection H02J7/0045
• CPC Class Codes: Y10S 320/15 Polarity control
• CPC Class Codes: Y10S 320/20 Polarity

Abstract

Solid state jumper cables for connecting two batteries in parallel, having two bridge rectifiers for developing a reference voltage, a four-input decoder for determining which terminals are to be connected based on a comparison of the voltage at each of the four terminals to the reference voltage, and a pair of relays for effecting the correct connection depending on the determination of the decoder. No connection will be made unless only one terminal of each battery has a higher voltage than the reference voltage, indicating "positive" terminals, and one has a lower voltage than the reference voltage, indicating "negative" terminals, and that, therefore, the two high voltage terminals may be connected and the two lower voltage terminals may be connected. Current flows once the appropriate relay device is closed. The relay device is preferably a MOSFET (metal oxide semiconductor field effect transistor) combined with a series array of photodiodes that develop MOSFET gate-closing potential when the decoder output causes an LED to light.

Claims

1. A device for use in connecting in parallel a first battery having two terminals to a second battery having two terminals, said device comprising:

conductor means for enabling current to flow to and from each of said four terminals;

means for comparing each of the voltages of said four terminals to a reference voltage, said voltages sampled from said conductor means, to determine which of said four terminals have voltages higher and which of said terminals have voltages lower than said reference voltage, said comparing means generating a high signal for each of said four terminals having a higher voltage and generating a low signal for each terminals having a lower voltage, said high and low signals generated by said comparing means forming a set of signals;

means for connecting either terminal of said first battery to either terminal of said second battery, said connecting means responsive to said high and low signals from said comparing means, said connecting means connecting one terminal of said first battery for which said comparing means has generated said high signal to one terminal of said second battery for which said comparing means has generated said high signal and the remaining terminal of said first battery for which said comparing means has generated said low signal to the remaining terminal of said second battery for which said comparing means has generated said low signal from so that said first battery and said second battery are connected in parallel; and

two bridge rectifiers for selecting said reference voltage from said voltages of said four terminals so that said reference voltage is higher than the lowest voltage of said four terminals and lower than the highest voltage of said four terminals.

2. The device as recited in claim 1, wherein each of said bridge rectifiers selects a low voltage and a high voltage, said low voltages of said two rectifiers being interconnected to produce an interconnected low voltage and said high voltages of said two rectifiers being interconnected to produce an interconnected high voltage, said interconnected high voltage being combined with said interconnected low voltage to produce a reference voltage approximately halfway between said interconnected high and low voltages.

3. A method for connecting in parallel a first battery to a second battery, each of said first and second batteries having two terminals, said method comprising the steps of:

generating a reference voltage;

comparing the voltage of each of said terminals of said first and second batteries to said reference voltage;

generating a first signal for each terminal having a voltage higher than said reference signal;

generating a second signal for each terminal having a voltage lower than said reference signal;

establishing a digital memory address for each combination of first and second signals, said digital memory address having an output for each combination of first and second signals wherein only one signal from said first battery is high and only one signal from said second battery is high;

routing said first and second signals to the correct memory address; and

connecting, in response to said output of said memory address, the terminal having said first signal of said first battery to the terminal having said first signal of said second battery and the terminal having said second signal of said first battery to the terminal having said second signal of said second battery on receipt of said output from said memory address.

4. The method as recited in claim 3, wherein said reference voltage is selected to be approximately halfway between the highest and lowest voltage of said terminals.