Automotive Batteries Questions and Answers

Answer: A

Four hundred milliamps is roughly ten times the acceptable figure and will flatten a battery in a few days. The battery itself has tested sound. Fuse by fuse investigation identifies the circuit responsible. 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. Reading the definition literally, rather than recalling a summary, avoids the usual confusion.

Answer: B

Cold cranking amps is the rating that matters for starting, because it is measured at the temperature and duration that cranking actually involves. A replacement battery must meet or exceed the specified figure. 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. Most errors here come from carrying across a result from a neighbouring case where it does not hold.

Answer: C

Specific gravity reads the state of charge, volt drop under load exposes a poor connection, and parasitic drain measures what is left running. Each is a distinct diagnostic with its own acceptance figure. 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. Naming what changes and what stays the same is the reliable route through questions of this shape.

Answer: D

A starter battery has thin plates for high current and tolerates only shallow cycling, so repeated deep discharge destroys it. A discharged battery genuinely does freeze more readily, which makes the last option a real secondary hazard. 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. A limit that survives making every external component ideal is an intrinsic one, and worth knowing for that reason.

Answer: A

Thick flat plates survive hundreds of deep cycles at the cost of a lower cranking current. Stop start batteries cycle frequently but only shallowly, which makes the last option a genuinely tempting near miss. Leisure and forklift batteries are deep cycle types. 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: B

A charged battery resists freezing to around minus sixty degrees, while a discharged one freezes near minus ten because the acid has entered the plates. A frozen battery cracks its case and is destroyed, which is why winter charge matters. 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. The quantity that varies and the quantity that does not are worth naming before any substitution is attempted.

Answer: C

Both plates convert to lead sulphate on discharge, the positive from lead dioxide and the negative from sponge lead. Charging reverses both reactions. Confusing the plate or the direction is the usual error, which is why each option is a genuine half truth. Most errors here come from carrying across a result from a neighbouring case where it does not hold. Tracing the requirement back to the physical constraint that produces it makes the answer follow.

Answer: D

Sulphate ions leave the electrolyte for the plates and water is produced, so the specific gravity falls. That is precisely why a hydrometer reads the state of charge. The change of density is the direct chemical consequence. Naming what changes and what stays the same is the reliable route through questions of this shape. The shared behaviour explains why these belong together and the differences explain why both exist.

Answer: A

Once most of the sulphate has converted, further current electrolyses water and bubbles appear. Specific gravity does rise during charging, which makes the second option a real observation with a different meaning. Prolonged gassing wastes water. Working the distinction through on a single concrete case fixes it more firmly than any rule of thumb. Naming the cost of a choice alongside its benefit is what turns a fact into a design decision.

Answer: B

The gassing voltage is around 14.4 volts and sustained charging much above it boils the electrolyte away. Regulators are set close to that figure deliberately. Sixteen volts would destroy the battery and the electronics quickly. A symptom that appears under one condition and not another is what narrows the diagnosis quickly. Most errors here come from carrying across a result from a neighbouring case where it does not hold.