I have a couple of hand held battery operated vacuums.
The internal brass charging contacts that are suppose to make contact when the power switch is turned off will not always conduct good enough to recharge the batteries. It is a bad design that I have been unable to correct by modifying the contacts.
What I have been able to do is to wiggle the off switch every time I need to recharge. This gives me the best shot at seating the contacts.This has worked for the most part. The problem is that I can not determine %100 of the time if the vacuum is actually charging.
Here's the question............The vacuum uses a low voltage AC output brick power supply. Is there a way to make a add on pickup/sensor for the brick or two conductor charging wire that will let me know if the contacts are made and current is flowing? I do not want to cut into the circuit.