Tell me if I'm doing this right with my multimeter (UPDATE)

Use alligator clips or similar devices so you could attach the leader to both sides and then walk away for at least 5 minutes and then take a reading. Most cars go through a few minutes of higher than normal draw when electronics our first connected. It Will likely drop but also keep in mind many electronic meters will go into an auto shutdown mode after a few minutes, so maybe take a look every two minutes or so and note the readings