How to Disable Low Voltage Sensor Auto Battery Chargers

In addition to the charger leads (seen above), you will also connect two battery probes to this electrical circuit.

A low-voltage sensor on an automotive battery charger is intended to be a safety feature that prevents the battery charger from damage due to overheating. Since the sensor is integrated into the charging circuit electronics, it is difficult (if not impossible) to disable the sensor without damaging the charger. There may be certain circumstances, however, where it may be necessary to bypass the low-voltage sensor on the charger; therefore you will have to create a parallel circuit that "fools" the charger into operation.

Things You'll Need

• Automobile with installed dead battery
• Battery charger
• Alligator-clip style battery probes
• Nine-volt alkaline battery

Instructions

1. Connect the black battery charger lead to the negative terminal on the automotive battery. Connect the red battery charger lead to the positive terminal on the automotive battery.

2. 

   Sample alligator-clip battery probe

   Clip one end of the first alligator-clip battery probe to the positive terminal on the automotive battery. Clip one end of the second alligator-clip battery probe to the automobile chassis. Do not allow the alligator-clip battery probes to touch each other.

3. Turn on the battery charger. Attach the free end of the second alligator-clip battery probe to the negative terminal on the nine-volt battery. Press the "Begin Charging" button, and momentarily touch the first alligator-clip battery probe to the positive terminal on the nine-volt battery.

4. Remove the first alligator-clip battery probe from the automotive battery. Remove the second alligator-clip battery probe from the nine-volt battery and from the automobile chassis.

Tips & Warnings

• "Jump-starting" a battery charger may void your charger's warranty, and is not recommended.

• The battery charger may cause the nine-volt battery to spark; use extreme caution when attempting to use an alkaline battery to "jump-start" a battery charger.

• Using a battery charger of any kind can pose a fire hazard.

References

• "Principles of Electric Circuits"; Thomas Floyd; 1996
• Georgia State University: DC Power in Series and Parallel Circuits