Hi

My mom has had a couple of dead batteries over the past few days. They are separate vehicles. Neither one had been started for over six weeks.

She doesn't want to remove the batteries from the vehicles, so just clamps the charger onto the terminals without disconnecting anything and charges that way.

I am wondering if that will damage the vehicle's electrical system in any way. The electrical system sees 12v from the battery anyways, so what is 12v from a charger going to do?

What do you think?

 

The way electricity works, you can apply more _voltage_ to a circuit, but you can't force more _current_ than the circuit draws. As you say, given that the charger is 12vdc, and the system is 12vdc, then you'll be fine.

Just don't hook up the charger backwards and don't try to start the car with the charger still attached - unless the charger is rated to support that kind of current.