Originally Posted by jevonmorris
Ok I now realize that It can be done with isolated chargers. Does anyone know how to find out if a charge is isolated or not? I have not really seen anything in the info online or on the boxes in the stores that says if a particular charger is isolated or not.
Lets see. Plug a charger into a GFI protected outlet. Connect the negative output to the wiring ground wire. If the GFI pops it isn't isolated. Repeat for the positive output.
If you have two of the chargers you can plug them in and then measure for DC voltage between the positive output on one unit and the negative output on the next one. If they are isolated you wont see any voltage, DC or AC. If you hook them together and they aren't isolated you will see sparks and most likely blow a breaker somewhere.
Ive never seen a 12V automotive battery charger that wasn't isolated. That doesn't mean they don't exist, I just have never seen one. And if I was a manufacturer I wouldn't sell one that wasn't isolated.