Let's say you are driving home from a party or a sporting event. It's pouring rain and, as you drive home, your car battery dies. While you'd probably be better off waiting for the rain to stop, if you are in a bind you can, technically, charge your battery in the rain.
Pull both vehicles to the side of the road, facing each other. If the cars are lined up nose-to-rear, the jumper cables won't reach both batteries (unless one of the vehicles has a rear-mounted engine).
Ensure that the electrical systems of both cars are turned off before opening the hoods.
Drape a tarp or another kind of water-resistant material over the open hoods. This keeps water away from the battery and, in turn, protects you from conducting electricity.
Connect the red (positive) cables to the corresponding positive terminals on each of the batteries. Do the same with the black (negative) cables.
Wait a few minutes for the battery to charge sufficiently.
Attempt to start the engine. If the car doesn't start, wait an additional 10 minutes to allow more of a charge, then try again. If it continues to not start, your car battery may simply be dead.
Pull your car to the side of the road.
Shut the engine off and make sure that all electronics are turned off. This includes the light that turns on when your car door opens.
Open the hood and drape a tarp or another water-resistant material on the hood to shield the car engine from rain.
Connect the red (positive) clamp to the positive terminal on the car battery. Do the same for the black (negative) clamp.
Flip the switch on your car battery charger and allow the device up to 20 minutes to charge the battery. Depending on the type of charger you have, you might have to turn a crank to build up the battery charge before transfer.
Turn the key and start your engine. If it does not start, wait another five to 10 minutes. If it does start, exit the vehicle and disconnect the charger.
