A lesson in automotive batteries
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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 per cent 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 here’s a bit of “battery speak” you may hear from time to time, or see printed on the battery.
Cold Cranking Amps (CCA): The number of amperes a lead acid battery at -17.8C can deliver for 30 seconds and maintain at least 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 heavy duty diesel on a chilly morning are going to be slim to none.
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 delivers 5 amps for 20 hours delivers 100 AH of capacity.
Reserve Capacity Rating (RC): The time in minutes that a new, fully charged battery will deliver 25 amps at 26.7C and maintain a terminal voltage equal to, or higher than, 1.75 volts per cell. This rating represents the time the battery will continue to operate essential accessories if the alternator fails.
Car battery types explained
With such a variety of battery types available, it’s extremely important to select the correct one.
Calcium batteries are the most common battery fitted to vehicles. In these batteries, a small amount of calcium is added to the lead plates to increase durability. Some calcium batteries also have silver added to increase the cranking power and overall efficiency.
Benefits of a calcium battery:
●High cold cranking amps
●Increased shelf and service life
One downside to calcium batteries is the charging requirement if they go flat.
A modern vehicle charging system is sufficient to keep a calcium battery charged under normal circumstances, but an alternator output is insufficient to bring a flat calcium battery back to full charge.
The solution is to have the battery either charged by a professional or at home with a smart charger.
Absorbent Glass Mat (AGM)
An AGM battery is a high performance battery which is able to endure the increased demands of modern vehicles.
Benefits of an AGM battery:
●Higher durability and cycle life when compared to a calcium battery
●High charge acceptance which is critical for modern battery management systems
●Leak-proof and spill-proof
●Excellent starting power, so you can rely on the engine starting — even at a low state of charge
Enhanced Flooded Battery (EFB)
The EFB uses some design features of the AGM battery to deliver a design that is able to cycle deeper and accept higher charge rates. The EFB is commonly found in entry level stop-start vehicles.
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.
With winter round the corner, 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 is common with imported vehicles.
A battery specialist will be able to test your battery and recommend the best replacement.