09 April 2024
All You Need To Know About Your Vehicle’s Battery

No battery, no commute, so take care of your vehicle’s battery.

For the purpose of this article, we’ll focus on an internal combustion engine (ICE) vehicle’s 12-volt battery. This battery can be found under the bonnet in the engine compartment, or in a specific purpose-built recess in the boot.

There are some rare occasions where the 12-volt battery can be found under one of the seats in a multipurpose vehicle (MPV) or in the footwell of some supercars. There are also some higher-end vehicles which may feature two batteries instead of just one, with one usually smaller than the other.

In any case, the main function of the 12-volt battery is to provide cranking power to start your vehicle’s ICE. Its other function is to provide protection against voltage spikes and surges to the vehicle’s various computers.

With the engine running, the alternator provides electricity to the various components of a vehicle as well as charging the battery. When the engine is not running, power to run lights, the infotainment system, alarm and security system, and stereo comes from the battery.

This is why it is not a good idea to run these items for too long with the engine off, since the alternator, which is driven off the engine, is not spinning and charging the battery.

alternator, driven by the engine via a serpentine belt

Types of Batteries

We’ll focus on the four main types of batteries that are readily available in the market. First, the two wet-cell types.

Flooded Lead Acid Battery (FLAB)

This is the oldest type, is very common and the most affordable. Most FLABs are typically comprised of six cells of lead-antimony plates, which are immersed (flooded) in a sulphuric-acid-and-water electrolyte solution.

Occasional maintenance is required for this type of battery, by checking and topping off each cell to the required level with battery water. FLABs must also be installed vertically to prevent the electrolyte from spilling.

If discharged to below 50% of the rated capacity, FLABs will experience significant shortening of their lifespan.

Enhanced Flooded Battery (EFB)

The EFB is also a common battery type. If you’ve heard of mechanics and fellow car owners talking about maintenance-free batteries, they’re likely referring to the EFB. EFBs still contain an electrolyte solution and cells of lead-antimony plates, but they’re all sealed within the outer plastic housing.

This battery type was introduced to provide more lifespan than its older FLAB ancestor. However, just like its ancestor, EFBs should be mounted vertically and should not be discharged to below 50% of their rated capacity, lest their lifespan is significantly shortened.

Next are the two common types of dry cell batteries.

Gel Cell Battery

Gel cell batteries, or gel batteries, were developed as a spill-proof version of the FLABs and EFBs. Instead of lead-antimony plates, gel batteries feature calcium-lead plates. Silica is added to the electrolyte to turn it into a spill-proof gel.

Gel batteries can be horizontally-mounted if need be, and are more shock- and vibration-resistant than FLABs and EFBs.

Gel batteries are also better suited to deep-discharge applications such as vehicles with very high-powered custom in-car audio installations, and will not wear out as quickly as FLABs and EFBs.

Absorbent Glass Mat Battery (AGM)

Although AGMs are referred to as dry-cell batteries, they’re actually quite similar to the wet-cell types. A fibreglass separator, or glass mat, absorbs the electrolyte and holds it in place.

AGMs can charge up to five times faster than their wet-cell counterparts. They’re also capable of being deep-discharged like the gel batteries. Naturally, AGMs are the most expensive battery-type of the four.

Modern cars with auto engine start/stop technology and mild-hybrid vehicles that recover energy from braking use AGM batteries. For such vehicles, replacement batteries must be of the AGM type, and the other three types should not be used.

One More Dry-Cell Battery

We haven’t forgotten lithium-based 12-volt batteries. These offer much stronger engine cranking and can charge up much quicker than FLABs and EFBs. They’re also much lighter than most other battery-types, but are much more expensive and are primarily used in weight-reduction scenarios, such as in motorcycles and motorsport applications.

Unless you know what you’re doing, there’s no need to spring for lithium-based batteries.

Replacing Batteries

The important thing to look out for is that the replacement battery must be of the same capacity as the outgoing one, meaning it needs to have the same or better cranking amps (CA) or cold cranking amps (CCA).

Cars with engine start/stop technology and/or mild hybrid drivetrains require AGM batteries, and only these should be used for replacement. Older vehicles which use FLABs or EFBs can be replaced with FLABs, EFBs and gel batteries, or even AGM if the vehicle owner is feeling generous.

Something else we’ve noticed is that regardless of battery type, the change interval in Singapore is around two years. This is likely due to our climate, driving conditions and the increased popularity of dashcams.

Yes, dashcams. A dashcam that is set to operate most if not all the time when parked can contribute to shorter battery lifespan, so keep that in mind when choosing your dashcam’s ‘parking’ setting.

Gel cell or AGM batteries would be more suitable for vehicles with permanently-wired dashcams, or you could choose to have an accessory battery pack installed specially for this purpose..

I’ve got a dead battery HALP!

Many of us have faced this dreaded scenario before.

We go to our car, unlock it, get in the driver’s seat and try to start the engine, only to be met with a solitary click or a series of clicks from the starter motor and nothing else. Sometimes, the engine may crank very slowly but doesn’t fire into life.

Here are two methods of jump-starting a vehicle with a dead battery.

1. Two-Vehicle Jump-Start

The first item needed for a two-vehicle jump-start is a pair of jumper cables. Be aware though, not all jumper cables are created equal. See the two images below:

jumper cables with thinner-gauge wires
jumper cables with thicker-gauge wires

Always use a quality set of jumper cables with thicker-gauge wires. The reason for this is because starting an ICE requires high power draw. A thinner-gauge set of jumper cables may not be able to deliver all the cranking amps needed at best, or start to overheat and present a fire hazard at worst.

Now that a suitable set of jumper cables that are sufficiently long have been obtained, get a friend to help. Doing this as a tag-team makes things so much easier.

First, drive the boosting vehicle to the one with the dead battery so that the batteries or manufacturer-specified jump-points are in relatively close proximity. In most cases, this would mean engine-bay to engine-bay.

Then, get your helper to hold one end of the jumper cables up and apart from each other.

This is important because the jaws of the jumper cable should never come into contact with each other, lest a short circuit is created that can potentially fry sensitive electronics and also start a fire.

Get the helper to connect the red cable’s jaw-end to the positive battery terminal of the vehicle with the dead battery. Then do the same on the boosting vehicle.

With this done, the helper will connect the other jaw-end of the black cable to a suitable body grounding point on the vehicle with the dead battery. Usually this would be a bolt on the strut tower, the grounding point on the engine itself, or the negative terminal of a manufacturer-specified jump point.

Finally, proceed to connect the the jaw-end of the black cable to the negative battery terminal of the boosting car. Both vehicles are now electrically connected to each other. We can proceed to jump-start the vehicle with the dead battery.

Get the helper to sit in the driver’s seat of the boosting vehicle, start the engine, and then bring engine revolutions up to 2,500rpm. This will allow the boosting vehicle’s alternator to charge at its rated capacity and help the jump-starting process.

Finally, jump into the dead-battery vehicle’s driver seat, turn off all unnecessary ancillaries such as the aircon, headlights and stereo, then proceed to start the engine. It should fire into life normally. If it doesn’t, try one more time and then call for a tow truck if the engine doesn’t start the second time.

With the distressed vehicle’s engine now running, disconnect the jumper cables after a couple of minutes in this order.

  • negative on dead-battery vehicle
  • negative on boosting vehicle
  • positive on boosting vehicle
  • positive on dead-battery vehicle

Remember never to allow any jumper cable-ends to contact each other or the bodywork of either vehicle during this procedure.

The dead-battery vehicle can now be driven to a workshop for a battery health check and replacement if needed.

2. Jump-Pack Jump-Start

Jump-packs come in all shapes and sizes, with the more powerful ones holding a bank of lithium cells. There are even supercapacitor-based jump packs that can charge their built-in supercapacitors with a dead battery’s remaining charge, and discharge all of that energy in a quick burst to start an engine.

Using a jump-pack is pretty simple. Connect the black cable to the negative battery terminal, and the red to the positive of the distressed vehicle. Remember not to touch any part of the bodywork with the jaw-ends.

Then turn on the jump-pack, start the engine normally, and disconnect the jump-pack.

Seven Tips to Extend Your Vehicle’s Battery Lifespan

The big question at this point is how should one care for their vehicle’s battery? Here are seven tips.

1. Avoid prolonged periods of inactivity

Modern vehicles have computers that monitor various aspects and functions. When parked, most of these computers go to sleep, but one or two may awaken at select periods to monitor certain things, like the security system. This, naturally, puts a small load on the vehicle’s battery and causes it to discharge.

If a vehicle is to be parked for more than a week, it is advisable to connect a good quality trickle charger to the battery to keep it charged up for the next engine start and commute. Trickle chargers of higher quality are also able to desulphate lead sulphate crystals built up on the battery plates to improve the battery’s health.

If you live in a HDB flat or condominium where power outlets are not available, consider disconnecting the negative terminal lead instead to cut off any electrical draw.

2. Avoid too many short journeys

Along with not letting a vehicle sit parked for too long, short start-stop journeys put a huge strain on the electrical system since the alternator would not have sufficient time to charge the battery up.

Modern vehicles also feature auto start-stop technology which kills an engine when stopped in traffic and starts it up again when one is ready to move off. Auto start-stop is an even larger strain, and combined with short journeys actually accelerate battery drain.

If your typical commute involves short journeys of five kilometres or less, or a purely street-based commute with multiple traffic-light stops , consider taking a longer drive of around 50-100km at least once a week, if not twice.

Simply jump on the nearest highway and drive around the island until you circumnavigate your way back home, or go visit a relative or friend who lives further away. This will allow the alternator to charge more optimally and the battery itself won’t be subject to heavier loads during a longer distance cruise.

3. Unplug cables and accessories

Parasitic draw is a large but often hidden cause of battery drain. Mechanics have encountered situations where a brand new battery goes flat within a month, and the parasitic-draw issue was painstakingly tracked down to an errant electrical accessory that continued to stay powered on while the vehicle was turned off.

Consider disconnecting your USB cables and devices, and any other accessories that are powered by the vehicle’s electrical system before locking and leaving your vehicle.

Which then brings us to the next tip…

4. Turn off lights when locking and leaving your vehicle

5. Keep the terminals clean

Another source of poor electrical performance in a vehicle is corroded battery terminals. We’re talking about the unsightly green powdery stuff that builds up on the terminals of FLABs and EFBs, and can cause connection issues.

A DIY remedy is to pour some hot water on the terminals to flush away the build-up. A small copper brush and degreaser can also help with cleaning duties.

Once the terminals are clean, apply a thin layer of automotive grease to the terminals to reduce the incidence of such corrosion. Also inspect the terminals once a month and during each service.

6. Have the battery tested periodically

When booking a service, you should request to have your vehicle’s battery health ascertained. This involves connecting a tester to the terminals and applying a load to see if the battery’s rated CA or CCA matches what the tester is seeing, as well as its state of charge.

Readings that are significantly lower could be indicative of a battery on its last legs.

7. Do not wait to replace an ageing battery

A tell-tale sign of a dying battery is a noticeably longer duration to crank the engine over into life. Engine cranking would also be slower and feel more strained.

Another, for more modern cars with auto start-stop technology, is the engine remains running while an advisory warning pops up on the instrument cluster saying something to the effect of “Auto Start/Stop Unavailable – Battery Charge” or similar.

One more is a bunch of unrelated error messages and codes that get thrown up once the vehicle is started.

All of these point to a battery that’s on its way out.

Since no one likes to be left stranded with a dead vehicle, have your vehicle’s battery tested periodically and changed around every two years, or when the tested CA is significantly lower than the battery’s rated CA, whichever happens first.


Well, don’t be.

AutoApp can handle all of your car’s servicing needs and keep you updated along the way. Battery health checks can be scheduled together with your regular servicing, and we’ll even remind you when it’s due for replacement.

Our panel of partner workshops are carefully curated to offer the most optimal and timely servicing solutions for your car. We’ll also remind you when your next servicing is due so that you don’t have to worry about getting it done on time.

Other safety-related and maintenance checks such as the wear of brakes and tyres are checked during servicing with Autoapp.

Leave the hassle to us. Let go, let AutoApp.

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