Though it's rare, it is possible to fry an alternators diod/rectifier bridge when jumping that car from another.
If you had the key in the "On", or "Acc" position on the car being jumped, then the car that is running is forcing electricity into the jumped car's starting/charging system.
The alternator on the jumped car is designed to allow electricity to flow only one way, but you forced electricity to flow in the opposite direction.
But you wouldn't have fried your entire electrical system because the fuses in the fuse box wouldn't allow that.
In the future, make sure your ignition key for the car being jumped is in the off position. And once you've allowed the battery to charge for awhile, disconnect the bat cables and then try starting that car.
The best way to do this is to remove the dead bat from the vehicle, and then connect the jumper cables. But it can be done safely the other way.
Monday, February 22nd, 2010 AT 8:36 AM