Automotive Batteries Questions and Answers

Answer: C

The density figure is correct, but a sealed battery has no removable vent plugs and cannot be sampled. Such batteries are assessed by voltage, load or conductance instead, and some carry a built in indicator for one cell only. The order in which the effects act is what decides the outcome, so it is worth establishing first. A symptom that appears under one condition and not another is what narrows the diagnosis quickly.

Answer: D

The first two are correct, but surface charge makes an immediate reading misleadingly high and the battery must rest or be briefly loaded first. Each test has a precondition that decides whether the number means anything. Checking which component actually carries the load settles most questions of this kind at once. The order in which the effects act is what decides the outcome, so it is worth establishing first. Most errors here come from carrying across a result from a neighbouring case where it does not hold.

Answer: A

Without registration the system charges for an aged battery and the new one is chronically undercharged, which takes months to show. The timescale rules out a drain or a failed alternator. Fitting the wrong type is the other real candidate. Tracing the requirement back to the physical constraint that produces it makes the answer follow. Checking which component actually carries the load settles most questions of this kind at once.

Answer: B

Twelve volts cannot drive a dangerous current through skin, so electrocution is not among the hazards. Hydrogen, acid and short circuit heating are all real. High voltage traction systems are an entirely different matter. The shared behaviour explains why these belong together and the differences explain why both exist. Tracing the requirement back to the physical constraint that produces it makes the answer follow. Naming what changes and what stays the same is the reliable route through questions of this shape.

Answer: C

Typical acceptable figures lie between twenty and fifty milliamps once every module has entered sleep mode. A larger drain flattens the battery over days and is found by working through the fuses. Naming the cost of a choice alongside its benefit is what turns a fact into a design decision. The shared behaviour explains why these belong together and the differences explain why both exist. Working the distinction through on a single concrete case fixes it more firmly than any rule of thumb.

Answer: D

Overcharging boils the electrolyte away, undercharging leaves the battery permanently low, and sulphation is the crystallisation that follows from standing in that condition. The three are linked but distinguishable. Reading the definition literally, rather than recalling a summary, avoids the usual confusion. Naming the cost of a choice alongside its benefit is what turns a fact into a design decision. A symptom that appears under one condition and not another is what narrows the diagnosis quickly.

Answer: A

The green eye is a hydrometer float in a single cell, so it reports that cell and nothing else. A good indication does not clear the battery. Some consumer batteries do carry test buttons, which makes the last option a real feature elsewhere. Most errors here come from carrying across a result from a neighbouring case where it does not hold. Reading the definition literally, rather than recalling a summary, avoids the usual confusion.

Answer: B

A faulty cell elsewhere in the battery is invisible to it, so a green eye with a battery that will not crank is entirely possible. A low level does turn it clear, which makes the last option a partial truth about its second function. Naming what changes and what stays the same is the reliable route through questions of this shape. Most errors here come from carrying across a result from a neighbouring case where it does not hold.

Answer: C

White or clear means the level has dropped below the float, which on a sealed battery cannot be corrected. Topping up is impossible on a sealed unit, which is exactly why the last option tempts anyone who has worked on older batteries. Working the distinction through on a single concrete case fixes it more firmly than any rule of thumb. Naming what changes and what stays the same is the reliable route through questions of this shape.

Answer: D

A replacement must match the physical size, the terminal positions and polarity, and meet the capacity and cranking figures. The date code matters for stock rotation rather than fitment. Getting the terminal layout wrong makes the leads too short. Tracing the requirement back to the physical constraint that produces it makes the answer follow. Checking which component actually carries the load settles most questions of this kind at once.