Your car’s battery is essential to making sure your vehicle starts every day. It ensures that the lights light up, the wipers wipe and that the music plays. Your battery is charging whenever your car is running, but it only has so much life and will eventually need to be replaced.
Modern vehicle electrics rely heavily on a constant battery voltage supply and even a voltage drop of a few volts can cause warning lights to appear. AA Roadservice stats show that up to 43% of breakdowns attend are battery related, so if your car sounds like it's struggling to start, now’s the time to get it checked.
For newbies to electrical terms here’s a bit of ‘battery speak’ you may hear from time to time, or see printed on the battery itself. Your understanding of the battery terminology below can help you to understand your car battery and help you to make the right choice when your 12-Volt lead acid has passed it serviceable life and is not reliable anymore.
Cold Cranking Amps (CCA)
CCA is the measurement of the ability of a battery to crank the motor of your car in cold temperatures. The number of CCA a battery can possibly have is not determined by the number of the plates in the battery but by a number of other factors mainly by the sum of total surface area of the plates in the battery. The CCA a battery can deliver at any point in time is determined by the number of amperes a lead acid battery at -18ºC can deliver for 30 seconds and maintain at least 7.2 Volts (1.2 volts per cell). It’s important to have the correct battery size for the vehicle – the chances of a small 300CCA starting up a large heavy-duty diesel on a chilly morning are going to be slim to none. Always check for the OEM recommendation of CCA needed for your car
Ampere - hour (AH)
A unit of measure for a battery’s electrical storage capacity, obtained by multiplying the current in amps by the time in hours of discharge. Example: A battery which can consistently delivers 5 amps for 20 hours delivers 100 AH of capacity. AH is very important for all modern vehicle with high power demands and lots of auxiliary features. It is the battery capacity (AH) that keeps them live when the car is turned off.
Reserve Capacity Rating (RC)
This rating represents the time the battery will continue to operate essential accessories if the alternator fails. It is measured by the time in minutes that a new, fully charged battery will deliver 25 amps at 27ºC and maintain a terminal voltage equal to, or higher than,10.5 volts (1.75 Volts per cell).
Car battery types explained
There are many variations of Lead Acid batteries. Each designed for its own particular application with specific discharge and charge characteristics. These battery types are specifically designed for a set designated end application.
It is important to pick the right lead acid battery for your particular application. Failure to do so can reduce performance and in some instances irreversible damage to the battery, resulting in a drastic reduction of its overall life span. Lead Acid batteries are broken down into two main categories; Flooded (or wet) Cells and Sealed Lead Acid Batteries (SLA) also known as Valve Regulated Lead Acid Battery (VRLA) All of these batteries contain small amount of calcium, silver, tin, and selenium, to form alloy with the lead grid.
Conventional (Wet Cell) Calcium Battery - Flooded Lead Acid Battery
Flooded Lead Acid batteries are conventional Lead based batteries. Lead calcium alloy has replaced antimony in its grids. A Calcium component (around 1%) is added to both the positive and negative plates. This works to reduce water loss through gassing in the battery and allows the battery container to be fully sealed and maintenance-free. Calcium also brings other benefits like high cold cranking amps, increased self and service life and best of all Lead Acid batteries with Calcium/Calcium plates can be maintenance free and is cost effective. However, once a calcium battery goes flat it needs a seven stage bench charge to bring it to 100% state of charge (SOC)
Absorbent Glass Mat (AGM) Battery – Sealed Valve regulated Lead Acid Battery
All lead based batteries use same basic chemistry and AGM is no exception. However, it is the different types of construction that makes the difference between the conventional flooded battery and AGM. The Absorbent Glass Mat is the genius here, it captures the electrolyte between the plates tightly compressed into each cell and held under pressure in a plastic battery box. This makes AGM the most efficient battery available. An AGM battery is a high performance battery which is able to endure the increased demands of modern vehicles.
Benefits of an AGM Battery:
- Spill proof through acid suspension in matting technology
- High specific power, low internal resistance ,responsive to load
- Up to 5 times higher charge acceptations than SLI (flooded Lead Acid Battery)
- Excellent life cycle compared to SLI (3X) and EFB (1.5X)
- Water retention (Oxygen and Hydrogen recombine to produce water)
- Extended self-life – low rate of discharge
- Less susceptible to sulphation and stratification
- Can tolerate deeper discharge cycle compared to SLI
- Handles high electrical loads
- Quickly recharges and extends cycle life
- Ideal for micro hybrid (start-stop applications)
- Vibration resistance due to sandwich construction
- Non-spillable and maintenance-free
- Greater mounting flexibility
Enhanced Flooded Battery (EFB) – Sealed Flooded Lead Acid Battery
Enhanced Flooded Battery (EFB) technology was developed to provide automotive manufacturers with a more cost effective battery solution for micro hybrids with ISS technology. EFB’s can be manufactured using the same equipment used for conventional flooded SLI batteries as they are flooded batteries. This makes manufacturing easier and also cheaper than AGMs. As the name suggests, EFB’s are an enhanced version of the flooded conventional battery. Enhancements include thicker plates, improved active material formulation and a high strength polyester scrim which is wrapped around the plate to help retain the active material. Their improved durability, cycle life and performance allow them to fit in between the conventional flooded and AGM designs.
Superior starting performance compared to conventional flooded • Improved cycle life compared to conventional flooded (2x). EFB batteries are often installed in vehicles with simple automatic start-stop systems. Due to their superior performance batteries with EFB technology are also increasingly used as replacements for conventional lead-acid batteries.
Gel Cell Battery – Sealed Valve Regulated Lead Acid Battery
Gelled batteries, or ‘gel cells’ contain a jelly-like substance which is due to silica gel being added to the acid. The advantage of these batteries is that it is impossible to spill acid even if they are broken. The disadvantage is that they must be charged at a slower charge rate to prevent overheating. They cannot be fast charged on a conventional automotive charger or they may be permanently damaged. Gel batteries are often found in golf buggies, back up for house alarms and electric toys and they do not come cheap
In extremes of weather, it’s a good time to think about battery health, especially if the battery is over five years old or the age is unknown which can be common with imported vehicles. A battery specialist or stockist will be able to test your battery and give the best replacement recommendation to suit the car. Remember a battery at 100% state of charge is not necessarily 100% state of health. A battery with poor state of health can cause expensive damage to other electrical components of the car namely starter motor and alternator.