Battery Desulphation Progress Monitor

A number of readers have asked how to tell when the Lead-Acid Battery Zapper has done its job and battery desulphation is complete. In the author’s experience, batteries that are going to respond to this treatment will generally show quite a high peak voltage across the terminals at the beginning of the treatment. If this steadily decreases and practically disappears, then the treatment is near to complete. This may take anything from a week to many months, depending on the size and condition of the battery. In the absence of an oscilloscope to monitor the voltage peaks, a simple peak detector can be constructed from a fast diode and 100nF capacitor. Any high-impedance multimeter (eg, most digital types) can then be used to measure the average DC voltage across the capacitor.

Circuit diagram: