Your Porsche battery is dead and located in your garage What is the best way to jump without damage?

The following comments consider the clamping procedure only. There are general safety procedures for this activity to be aware regardless of car type.

1990 Porsche manual page 103 shows emergency starting with jumper cables. Diagram shows first; connect positive cable clamp to positive post discharged bat. , second; positive cable clamp to booster bat. positive post ., third, connect negative cable clamp to negative post booster bat., lastly; connect negative cable clamp to bare metal on car with discharged battery. Read instructions on your cables.