Question

which post should be disconnected first when removing a battery?
negative
depends on battery construction
positive
either one - no differnece

Explanation:

When removing a battery, disconnecting the negative post first is a safety - related practice. This is to prevent accidental short - circuits. If the positive is disconnected first, and a tool accidentally touches the positive terminal and a metal part of the vehicle (which is connected to the negative terminal through the vehicle's frame), it can cause a short - circuit. By disconnecting the negative first, this risk is minimized as the negative is the ground reference.

Answer:

Negative