101 reputation
bio website
location
age
visits member for 2 years, 9 months
seen Jan 24 '12 at 18:59

Jan
24
comment What's happening when you give someone a boost?
See the first two paragraphs at: en.wikipedia.org/wiki/Jump_start_(vehicle)#Limitations
Jan
24
comment What's happening when you give someone a boost?
@Gregory Bell: Why is the negative terminal connected to the car frame? The last step, connecting to the car frame, completes the circuit between the two cars. This is the connection that can cause a spark when it is made. Lead acid batteries produce hydrogen gas, and a nearby spark can cause them to explode. The last (potentially sparking) connection is made away from the battery to eliminate (or at least reduce) the chance of an acid throwing explosion. Note the disconnections should be made in the opposite order of connections, since the first disconnect can also spark.