BATTERY TESTER WITH AN IMPROVED LOAD CIRCUIT

• US 3,848,181 A
• Filed: 09/18/1973
• Issued: 11/12/1974
• Est. Priority Date: 09/18/1973
• Status: Expired due to Term

• Current Assignee: Donald F. Fitzgerald, James O. Hebert Jr
• Original Assignee: Donald F. Fitzgerald, James O. Hebert Jr
• Inventors: Hebert, James O. Jr., Fitzgerald, Donald F.
• Primary Examiner(s): Smith, Alfred E.
• Assistant Examiner(s): Hille, Rolf
• Application Number:
  US05/398,489
• Time in Patent Office: 420 Days
• Field of Search: 324/29.5 320/48 340/249
• US Class Current: 324/429
• CPC Class Codes: G01R 31/36 Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC]
• CPC Class Codes: G01R 31/386 using test-loads

Abstract

An improved load circuit which may be utilized among others with a battery tester and method for the breakdown testing of batteries. The improved tester of the preferred embodiment utilizes a new and novel load circuit comprising a plurality of power transistors connected in parallel to each other and being connected to a new and novel bus structure which assures that each of the transistors carries its share of the total load. The battery tester also utilizes new and novel means to cool and insulate the test leads from heat during the use of the tester. In the broadest form of the invention the new and novel load circuit utilizes at least one power transistor to carry the load of the circuit. Also disclosed is a new and novel method for the breakdown testing of batteries utilizing the beforementioned load circuit.

Claims

1. An electrical load circuit for a battery tester for testing batteries having positive and negative terminals and wherein the load current that is allowed to pass through the battery is sensed and controlled, comprising:

a. a plurality of test leads, each lead having attached thereto a terminal battery connector;

b. reverse current means, associated with one of the test leads, for preventing a reverse flow of current;

c. a plurality of power transistors, associated with the test leads, said power transistors being connected in parallel to each other and in serieS with the reverse current means;

d. at least a first bus structure associated with the power transistors;

e. at least a second bus structure associated with the power transistors and electrically insulated at its one end from the first bus structure and electrically connected through its other end to the first bus structure, the bus structures also being electrically connected to one of the test leads; and

f. at least two emitter bias resistors being connected at a common point to the emitters of each power transistor, the opposite end of one bias resistor being connected to the first bus and the opposite end of the other bias resistor being connected to the second bus.

2. The load circuit as defined in claim 1 further comprising:

g. heat dissipating means, associated with the load circuit, for dissipating the heat generated by the load circuit.

3. The load circuit as defined in claim 1 further comprising a plurality of heat dissipating means, associated with the reverse current means, the power transistors, the test leads and the terminal battery connectors, for dissipating the heat generated by the load circuit.

4. The load circuit as defined in claim 3 wherein the plurality of heat dissipating means are connected in series with each other and comprise a coolant system having circulated therein a coolant.

5. An electrical load circuit for a battery tester for testing batteries having positive and negative terminals and wherein the load current that is allowed to pass through the battery is sensed and controlled, comprising:

a. a plurality of test leads, each lead having attached thereto a terminal battery connector;

b. reverse current means, associated with one of the test leads for preventing a reverse flow of current to the battery;

c. a plurality of power transistors connected in parallel to each other and in series with the reverse current means;

d. heat dissipating means, associated with the power transistors and the reverse current means, for dissipating the heat generated within the power transistors;

e. at least a first bus structure associated with the power transistors;

f. at least a second bus structure associated with the power transistors and electrically insulated from the first bus structure; and

g. at least two emitter bias resistors connected at a common point to the emitters of each power transistor, the opposite end of one bias resistor being connected to the first bus and the opposite end of the other bias resistor being connected to the second bus, the bus structures being insulated from each other at one end thereof and connected to each other at a common point and being also connected at the common point to one of the test leads.

6. The electrical load circuit as defined in claim 5 further comprising:

h. another heat dissipating means, associated with the test leads and the battery connectors, for dissipating the heat generated at the battery terminal and for electrically insulating the test leads from each other.

7. The electrical load circuit as defined in claim 5 wherein the reverse current means comprises a high current diode.

8. The electrical load circuit as defined in claim 5 wherein the reverse current means comprises a silicon controlled rectifier.

9. The electrical load circuit as defined in claim 5 wherein said power transistors comprise NPN transistors and said reverse current means is located in series with the positive terminal.

10. The electrical load circuit as defined in claim 6 wherein the other heat dissipating means comprises a pair of hollow flexible plastic tubings attached at one end thereof to each of the battery connectors and surrounding each test lead and being connected at the other end thereof to a coolant source;

and further comprising means, associated with the tubing for circulating the coolant through the tubing to cool the terminal connectors and the test leads.

11. In an electrical load circuit for a battery tester of the tyPe comprising a test battery in series with a load bank, the improvement comprising:

a. the load bank comprising a plurality of power transistors connected in parallel to each other and in series with the test battery;

b. at least two emitter bias resistors connected at one end to a common point and to the emitters of each power transistor;

c. at least two bus structures associated with the bias resistors and being insulated from each other at one end and electrically connected to each other through their other ends; and

d. one of the emitter bias resistors of each power transistor being connected at its other end to one of the bus structures and the other of the emitter bias resistors being connected at its other end to the other of the bus structures so that the combined voltage drop across any commonly connected bias resistors will be substantially equal to the combined voltage drop across any other commonly connected bias resistors.

12. The improvement as defined in claim 11 wherein the power transistors are NPN type.

13. The improvement as defined in claim 11 wherein the power transistors are the PNP type.

14. The improvement as defined in claim 11 further comprising heat sink means, associated with the power transistors, for removing the heat generated by the power transistors.