yes on not disconnecting the battery when running a car with an alternator [or computer], for an alternator test, read voltage across battery terminals while running, should be about 14V .... "resting" before testing applies to voltage tests after charging not SG reading

Bill

Moved over to the Passing Lane

"When we tug a single thing in nature we find it attached to the rest of the world" John Muir
"When we tug a single thing on an old truck, we find it falls off" me
Some TF series details & TF heater pics & Rust-a-holics Unanimous parking lot