Final answer:
True, modern load testers are connected in series with the battery cable to measure current, much like ammeters, which also measure current by being connected in series.
Step-by-step explanation:
The statement that modern load testers require connecting the tester leads in series with the battery cable to measure current is True. This method is similar to how ammeters are used to measure current. Both ammeters and load testers need to be connected in series to the circuit or device under test to accurately gauge the current flowing through them. Battery testers utilize small load resistors to draw current and test a battery's internal resistance, which is indicated by a change in terminal voltage under load conditions. High internal resistance suggests that the battery is weak.