Automatic battery and charging system tester with motor-driven carbon pile loading

• US 5,426,371 A
• Filed: 08/23/1993
• Issued: 06/20/1995
• Est. Priority Date: 09/11/1989
• Status: Expired due to Fees

• Current Assignee: Snap-On Technologies Incorporated (Snap-On Incorporated)
• Original Assignee: Snap-On Incorporated
• Inventors: Geisler, Ronald D., Salley, Glenn E., Rameshk, Sohrab S., Willems, Paul A., Becker, Thomas P., Thibedeau, Dennis G., Braun, Robert D.
• Primary Examiner(s): Regan, Maura K.
• Application Number:
  US08/111,594
• Time in Patent Office: 666 Days
• Field of Search: 324/429, 324/426, 324/430, 324/433, 340/636, 320/48
• US Class Current: 324/429
• CPC Class Codes: G01R 31/385 Arrangements for measuring battery or accumulator variables for monitoring G01R31/382

Abstract

A battery and charging system tester includes an automatically-operated carbon pile for loading the battery, the pile having a shaft therethrough rotated by a stepper motor, and a compression nut threadedly engaged with the shaft for movement into and out of engagement with the carbon pile in response to rotation of the shaft for varying the compression of the pile and, thereby, the impedance thereof. Probes are provided for sensing battery load current and output voltage, and the output current of an alternator charging unit. A feedback control circuit including a microprocessor operating under stored program control converts the analog probe outputs to digital signals and compares the battery output voltage and load current to selectively variable references for controlling the stepper motor to vary the battery load so as to regulate either the battery load current or the battery output voltage to a predetermined reference value, depending upon the test being performed. A selectively variable timer controls the time period during which the battery is loaded. A display indicates the reference values, the values of the parameters being regulated and the state of the timer.

Claims

1. Apparatus for testing the current output of a battery charging system comprising:

a carbon pile electrical impedance adapted to be connected to the battery for loading thereof;

compression means coupled to said carbon pile impedance for varying the compression thereof and thereby effecting variation of the impedance thereof, said compression means, including a rotatable shaft, and clamping means threadedly engaged with said shaft and adapted for engagement with the carbon pile;

a motor coupled to said compression means for driving same, said motor being coupled to said shaft for rotating same, thereby to move said clamping means relative to the carbon pile for varying the compression thereof;

a current sensor adapted to be coupled to the charging system for detecting the current, output thereof;

a voltage sensor adapted to be coupled to the battery for detecting the output voltage thereof;

a feedback control circuit coupled to said motive means and to said voltage sensing means and responsive to the battery output voltage for controlling said motive means to vary said impedance so as to regulate the battery output voltage to a predetermined value; and

display means coupled to said current sensor for monitoring the current output of the battery charging system while the battery is being loaded.

2. The apparatus of claim 1, wherein said current sensor includes a Hall probe.

3. The apparatus of claim 1, and further comprising a timer coupled to said feedback control circuit for controlling the time period during which the battery output voltage is regulated to said predetermined value, said timer including manually operable adjustment means for selectively adjusting the time period during which the battery output voltage is regulated to said predetermined value.

4. The apparatus of claim 1, wherein said display means includes means for displaying said predetermined value.

5. The apparatus of claim 4, and further comprising means for selectively varying said predetermined value.

6. The apparatus of claim 1, wherein said feedback control circuit includes a peak capture circuit for capturing the maximum current output value of the current charging system while the battery is being loaded and causing said display means to display that maximum value.

7. Apparatus for automatically loading a battery for testing thereof, comprising:

carbon pile electrical impedance adapted to be connected in series with the battery for loading thereof,

compression means coupled to said impedance for varying the compression thereof and thereby effecting variation of the impedance thereof, said compression means including a rotatable shaft, and clamping means threadedly engaged with said shaft and adapted for engagement with the carbon pile, a motor coupled to said compression means for driving same, said motor being coupled to said shaft for rotating same thereby to move said clamping means relative to the carbon pile for varying the compression thereof;

a feedback circuit coupled to said impedance for generating a feedback signal proportional to the load current through said impedance,

a drive controller coupled to said motor and to said feedback circuit and responsive to said feedback signal for automatically controlling the operation of said motor to regulate the load current through said impedance to a predetermined value,

and a timer coupled to said drive controller for selectively adjusting the time period during which said predetermined load current is maintained.

8. The apparatus of claim 7, wherein said drive controller includes a comparator for comparing said feedback signal with a reference signal corresponding to said predetermined value.

9. The apparatus of claim 8, and further comprising means for selectively varying said predetermined value.

10. The apparatus of claim 9, and further comprising a display for displaying said predetermined value.

11. The apparatus of claim 7, and further comprising a display for displaying the value of the load current.

12. The apparatus of claim 7, wherein said drive controller includes means for varying the rate at which said compression means is operated.