Question

Two technicians are discussing a vehicle that cranks slowly when the key is turned to the crank position. The positive battery terminal is noticably hotter than the negative terminal. Technician A says that the positive battery terminal must have an excessive voltage drop since it is hotter. Technician B says that the negative battery terminal must have an excessive voltage drop since it is cooler. Who is correct?

Answer 1

Technician A is more likely correct because a hot positive battery terminal usually indicates a poor connection or corrosion at the terminal, causing increased resistance and heat due to current flowing through it when cranking the engine.

Step-by-step explanation:

The question pertains to a scenario where a vehicle's battery cranks slowly and the positive battery terminal is noticeably hotter than the negative terminal. Technician A suggests that there must be an excessive voltage drop at the positive terminal since it's hotter. Conversely, Technician B believes the negative terminal must have the excessive voltage drop because it is cooler.

Generally, heat at an electrical connection indicates resistance, which can cause a voltage drop across the terminal, leading to excessive current flow through that resistance and resulting in heat. When the positive battery terminal is hotter, it is usually due to a poor connection or corrosion that has increased resistance at the terminal. This does not necessarily mean there's an excessive voltage drop across the terminal but rather at the terminal due to the connection issue. Technician A's assertion is more accurate since a high resistance connection at the positive terminal would cause it to heat up during high current flow like when cranking the engine.