Batteries – a layman’s guide
There are basically two types of lead-acid batteries used in the automotive industry: Vehicle Starter Batteries and Leisure Batteries. Today we will look at the batteries used to start your vehicle.
These days Starter Batteries have just one job to perform, namely to start the vehicle. Once the vehicle has been started most, if not all, the vehicle’s electrical requirements are supplied by the alternator. Yes, in winter when the heating system is on full (or heated clothing), the heated seats on high (and or heated grips), with the headlights on and the rear and front de-mist working then power could also be drawn from the battery as well. But, under normal circumstances, the alternator provides the electrical power for the vehicle.
How does a Starter Battery differ from a Leisure Battery?
In a Starter Battery, there are more lead plates and these plates are thinner. This has the effect of giving a higher amount of power for a shorter period of time. Exactly what a starter motor requires. This type of power delivery is measured in CCA (Cold Cranking Amps).
The trade-off is that there is less electrical power (Ah) to run the vehicle and it’s accessories. This is not usually a problem as the alternator is providing the power for the accessories.
In general, a Starter Battery’s resting voltage should never go below 12.24V at 20°C (80°F) as the battery can be damaged. Check the manufacturer’s specifications for the exact voltage.
A Leisure Battery has a fewer number of thicker Lead plates which allows it to provide a smaller amount of power for a much longer period. This is ideal for boats, motorhomes and the like which require power when the engine is switched off. This type of power is measured in Ah (Amp hours).
In general, a Leisure Battery’s resting voltage should never go below 12.06V at 20°C (80°F) as this can damage the battery. Therefore, a Leisure Battery can tolerate a deeper discharge before being damaged. Check the manufacturer’s specifications for the exact voltage.
Note there are batteries known as Deep Cycle Batteries that can tolerate a very high level of discharge. These are generally found in submarines and older forms of electric vehicles.
Cold Cranking Apps
The definition is: Cold Cranking Amps (CCA) are the numbers of amperes a lead-acid battery at 0°C (32°F) can deliver for 30 seconds and maintain at least 1.2 volts per cell (7.2 volts for a 12-volt battery).
So what does that mean for you?
The CCA determines how much power you have to start your vehicle in most climates. So:
- If your vehicle has a large engine, it needs a battery with a higher CCA.
- If your vehicle is kept in a cold climate, it requires a battery with a higher CCA
- If your vehicle has both a large engine and is kept in a cold climate it needs a much higher CCA.
- If you’ve moved from a warm climate to a cold climate, you need a battery with a larger CCA rating.
- If your vehicle lives in a nice, heated garage, then you might be able to fit a battery with a slightly lower CCA. This is strongly discouraged and should only be considered if a suitable battery is not available.
As a rough rule of thumb: the larger the engine and the colder the climate, the bigger the CCA. But there is a “but”.
If you’ve added lots of power hungry accessories, then your battery needs a large Ah rating. So you will need to find one with both a higher Ah and higher CCA. In this case, the physical size of the battery will usually be larger.
Assuming that no other factors have changed, when replacing the Starter Battery in your vehicle, you should fit one that has the same CCA or slightly higher CCA and the same or slightly higher Ah rating as was supplied with the vehicle when new. If the CCA isn’t specified on the battery, don’t buy it to start your vehicle!
Finally, always remember to check that the dimensions of the battery are the same and that it will fit in your vehicle.
I want to help you so, if you have any questions about Starter Batteries, please leave them below.