For about 30 yrs. I have used Battery Tenders on motorcycles, Tiger, lawn tractor, etc. If the battery is out, I connect the charger clips to the battery terminals. if the battery is out of the vehicle what choice do you have? I have 3 hooked up back VT (while I’m in Florida) and they’re all connected to the battery terminals. The batteries are currently in all 3 vehicles and connected as mentioned. Mark