Car Battery and Roadside Glossary

Ampere-hour (Ah) measures how much charge a battery can store. A higher Ah figure means the battery can supply current for longer before it runs flat.

Cold Cranking Amps (CCA) is the current a battery can deliver in a short burst to turn the starter motor. It is the clearest measure of how much starting power a battery has left.

Reserve Capacity is the number of minutes a fully charged battery can keep a car's electrics running if the alternator stops charging. Cars with heavy electrical loads need a higher figure.

A BCI group size is a standard code for a battery's physical dimensions and terminal layout. Two batteries with the same group size fit the same tray and clamp.

State of Health (SOH) shows how much of its original capacity a battery still holds, given as a percentage. A battery below 40% SOH needs replacing soon.

Terminal polarity is the position of the positive and negative posts on top of a battery. A battery with the posts on the wrong sides will not reach the car's cables.

An SLA battery is a sealed lead-acid battery with maintenance-free terminals. SLA units make up the Economy tier of car batteries.

An Enhanced Flooded Battery (EFB) is a tougher version of the standard flooded battery, built to handle frequent restarts. It suits cars with standard start-stop systems and costs less than an AGM unit.

An Absorbent Glass Mat (AGM) battery holds its electrolyte in glass fibre mats instead of free liquid. It is sealed, copes well with deep cycling and suits start-stop cars and cars with sensitive electronics.

A calcium battery uses calcium-alloy plates in place of standard lead-alloy ones. The plates lose less water and self-discharge more slowly, so the battery is sealed and never needs topping up.

A SpiralCell battery winds its pure lead plates into tight coils instead of stacking them flat. The design lowers internal resistance and self-discharge.

An auxiliary battery is a second, smaller battery that supports the main one, mostly in cars with start-stop systems. It powers accessories and electronics so the main battery can focus on starting the engine.

A HAT battery is built to keep working in sustained heat like an Abu Dhabi summer. Its construction resists the plate sulfation that high temperatures speed up.

The alternator is the engine-driven generator that charges the battery and powers the car's electrics while the engine runs. It produces alternating current and converts it to direct current for the car.

A dynamo is an older type of engine-driven generator that produces direct current straight from its windings. Modern cars use an alternator for the same job.

The voltage regulator controls the alternator's output so the battery is charged without being overcharged. When it fails, the voltage can climb high enough to damage the battery.

A start-stop system switches the engine off when the car stands still, for example at traffic lights, and restarts it when you move off. The extra restarts put more demand on the battery, which is why these cars use EFB or AGM units.

The Battery Management System (BMS) monitors the battery's charge and controls how the alternator charges it. It works from the details of the battery fitted, so it needs to know when a new one goes in.

The Engine Control Unit (ECU) is the onboard computer that manages the engine's fuel, ignition and sensors. It needs a steady supply from the battery and is sensitive to voltage spikes.

Parasitic drain is power taken from the battery while the car is parked and switched off. A faulty sensor, relay or aftermarket accessory is the usual cause.

Deep discharge means draining a battery close to empty, for example by leaving the lights on overnight. Car batteries are built to stay near full charge, so repeated deep discharges cut their working life.

Sulfation is the build-up of lead sulfate crystals on the battery plates. It reduces how much charge the battery can hold and gets worse with heat and deep discharges.

Stratification happens when the acid in a flooded battery settles into layers, with stronger acid at the bottom. It weakens the battery and is more likely after repeated deep discharges or when a battery is too small for the car.

Terminal corrosion is the white powder or rust that forms on battery posts and clamps. It blocks current flow, so even a charged battery can fail to start the car.

A swollen battery case has sides or a top that bulge outward. The change in shape signals plate sulfation and a weak State of Health.

A conductance test passes a small signal through a battery to measure its State of Health and cranking power. A digital tester shows the figures on the spot.

A jumpstart sends power from an external source, such as a power pack or another car, into a flat battery so it can turn the starter motor. Once the engine runs, the alternator takes over the charging.

A flatbed tow truck carries the whole car on a tilting bed, with all four wheels off the ground. It is the method used for luxury, sports and low-clearance cars.

A wheel-lift tow truck raises either the front or the rear wheels and tows the car on the other two. It suits standard sedans and compact cars.

A Vehicle Inspection Report (VIR) records a car's condition, including any existing damage, before it is towed. It is completed in under 5 minutes.

Winch recovery uses a powered cable line to pull out a car that cannot move under its own power, for example from deep sand or a ditch. Sand recovery units run a 9,000 kg-rated winch line.

Traction boards are ridged boards wedged under the tyres of a car stuck in sand. They give the wheels something firm to grip so the car can climb out.

A plug-patch repair seals a puncture from inside the tyre with a combined plug and patch. Done correctly, it lasts for the life of the tyre, unlike a plug on its own.

A space-saver is a narrow, lightweight spare wheel made for short distances only. It must not go above 80 km/h or be driven more than 80 km.

A run-flat tyre has stiff sidewalls that hold the car up after a puncture, so many cars fitted with them carry no spare. It can be driven at up to 80 km/h for up to 80 km after going flat.

The hard shoulder is the strip at the edge of a highway, outside the traffic lanes, kept for stopped vehicles. It is the safest place for a car that breaks down on a fast road.

UAE traffic law requires at least 1.6mm of tread across the full width of a tyre. A tyre worn below that limit has to be replaced.

Abu Dhabi traffic law requires hazard lights and a warning triangle for a vehicle stopped on a public road. On a highway the triangle goes 50 metres behind the car, and not using one carries a fine of AED 500.

Misfuelling means filling a car with the wrong fuel, such as petrol in a diesel engine. Running the engine on the wrong fuel damages the fuel pump and injectors.

Special 95 and Super 98 are petrol grades sold at UAE fuel stations. Special 95 suits most standard cars and compact SUVs, while Super 98 suits high-performance engines and many European luxury cars.