The
question can only be answered if you determine the
load that is being put on the batteryand the
load capacity
of the battery.I have run the radio in my
truck for two hours and it started without a problem.I have seen a luxury car with 12 or 14 interior lights run a battery down in 90 minutes from a door left open.Most original equipment radios draw very little current so that isn't much
of an issue.What can be
of concern is if you repeatedly drain the battery with powerful stereos, lights, powerwindows etc. then recharge it by running the engine.
Otherwise, we would strongly
question his or her sanity by choosing an uncovered flatbed
truck for transport, let alone allowing the use
of unsecured wooden scraps as a
loading ramp.