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Battery Spear, a specific tool or accessory used for testing batteries under load conditions, particularly in automotive or industrial settings. This tool is commonly known as a “battery load tester” or “battery load probe.”

Battery Load Tester (or Battery Spear):

  1. Purpose: The battery spear, or battery load tester, is used to simulate a heavy electrical load on a battery to assess its performance and capacity under real-world conditions.
  2. Design:
  • Probe Shape: Often shaped like a spike or a pointed tool that connects directly to the battery terminals or plates.
  • Internal Components: Includes a voltmeter or ammeter that measures the voltage drop or current draw when the battery is under load.
  • Shunt Resistor: Built-in low-resistance shunt to simulate the load, typically designed to draw a significant current without damaging the tester or the battery.
  1. Operation:
  • Connection: The battery spear is connected directly to the battery terminals.
  • Load Simulation: Upon activation, the tool applies a load to the battery, drawing current through the shunt resistor.
  • Measurement: The attached voltmeter or ammeter then displays the battery’s voltage or current output under load, allowing technicians to assess its health and capacity.
  1. Usage:
  • Diagnostic Tool: Used by mechanics, technicians, or service personnel to determine if a battery can sustain the necessary load for starting an engine or powering equipment.
  • Testing Conditions: Provides a more accurate assessment than measuring open-circuit voltage, as it tests the battery under conditions similar to its operational use.
  1. Safety Considerations:
  • Heavy-Duty Design: The tool is built to handle the high current draw without overheating or causing damage.
  • Protective Measures: Ensures that connections are secure and insulated to prevent accidental short circuits.


  • Automotive: Used to diagnose battery health and determine if it can provide sufficient power for starting the engine.
  • Industrial: Testing batteries used in backup power systems, telecommunications, or renewable energy applications to ensure reliability under load.

In summary, the battery spear or battery load tester is a specialized tool used for assessing battery performance under load conditions, providing crucial information for maintenance and diagnostics in various industries.

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