AA Car Care: a day in the life of an automotive battery
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That small rectangular box is hidden out of sight in a vehicle, and many drivers don’t really think about it until it’s too late.
Modern vehicle electrics rely on a constant battery voltage supply, and even a drop of just a few volts can cause warning lights to appear on your dashboard.
AA Roadservice stats show that up to 43 per cent of breakdowns attended are battery related, so if your car sounds like it's struggling to start, take it to an AA Auto Centre or an AA Approved Repairer before it’s too late.
Cold Cranking Rating (CCA)
This is the number of amperes a lead acid battery at minus 17.8 degrees Celsius 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, as a 300CCA battery might not start a large heavy duty diesel, which requires 700CCA to start on a chilly winter’s morning.
A unit of measure for a battery’s electrical storage capacity, obtained by multiplying the current (amps) by the time (hours) of discharge. Example: a battery which delivers 5 amps for 20 hours delivers 5 X 20 = 100 AH of capacity.
Reserve Capacity Rating (RC)
The time in minutes that a new, fully charged battery will deliver 25 amps at 26.7deg 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 or generator of a vehicle fails.
BATTERY TYPES EXPLAINED
There are many car battery types available to match different models of cars. It is very important to select the correct one; “if the shoe (or battery) fits” is no longer acceptable.
Calcium batteries are the most common battery fitted to vehicles. A small amount of calcium is added to the lead plates to increase durability of the battery. Some also have silver added to the plates to increase the cranking power and overall efficiency.
Benefits of a calcium battery:
- High cold cranking amps
- Longer shelf and service life (compared with hybrid batteries)
- Maintenance free
AGM (Absorbent Glass Mat)
The AGM 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 compared with 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
- Maintenance free
EFB (Enhanced Flooded Battery)
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 used in entry level vehicles with stop-start technology.
Gelled batteries, or "gel cells" contain a jelly-like substance which is produced when silica gel is added to the acid.
The advantage of these batteries is that it is impossible to spill acid even if they’re broken. The disadvantage is that they must be charged at a slower rate to prevent overheating. They cannot be fast-charged on a conventional automotive charger.
Gel batteries are often found in golf buggies, as a back-up battery for house alarms, and electric toys.
Winter is the most important time of year to think about battery health, especially if your battery is over five years old. A battery specialist will be able to test the battery and give a replacement recommendation if required.