There are two windings in most starter solenoids. 1) a "pull in" winding. 2) A "hold in" winding. The pull in winding is a high current, high magnetism winding that goes to ground through the starter brushes. After the solenoid pulls the drive into the flywheel, and the solenoid copper contacts close, this winding gets 12v on both ends of the winding. This deletes the winding from drawing current any longer. On a good system, with large enough wires, good connections, and a good battery, this pull in winding is only there for about 50 milliseconds. Not enough time for a driver to even know it happens. The hold in winding is a much smaller winding, and it goes to ground through the solenoid case. It's current draw is there until the driver releases the key. If the system fails, do to too small of wire, bad connections, or battery voltage a heat soaked starter can fail to pull in which fails to negate the pull in winding, pulling the full current until the driver releases the key! This can cause about a 50 to 60 amp draw, instead of only the 15 amp hold in draw.