Battery failure is most commonly identified when attempting to turn a cold engine; as such, failures are more common in winter when more power is required to crank the engine and other services such as heated rear screens and seats are placing additional demands upon the vehicle’s electrical system.
How batteries are specified
Most of us simply see the battery as a black box with a couple of terminals, but there is a little more to it than that. Other than specialised batteries used in electric vehicles (EVs), the vast majority of car batteries are based upon lead acid technology.
As with most rechargeable batteries, lead acid batteries deteriorate over time; therefore, the first thing to check is the age of the one you are replacing. The date of manufacture may or may not be visible on the battery body; if not, you may see a code with a letter (A to M) denoting the month and a digit identifying the year of manufacture.
There are two principal ratings to consider in selecting the appropriate battery and it is important to get the right one for your vehicle; otherwise, you will either spend too much or it will lack the power necessary to start your engine in adverse conditions. The amp-hours rating describes the overall charge – and thus the power delivery – capacity of the battery; therefore, the best you can afford is a good idea in this context. The cold cranking amps rating (CCA) denotes how much power it can output when starting a cold engine; the larger the engine, the higher the CCA figure required, with diesel engines mandating a higher output than their petrol counterparts.
Modern car engine compartments are tightly packed, so make sure that the battery you are planning to buy will fit in the space allowed. Also check that the terminal type and position is correct. From specialist batteries such as the Odyssey PC680 motorsport battery from suppliers such as http://www.grovesbatteries.co.uk/optima-odyssey.aspx?BatteryId=573 through to rather more mainstream models, you will find a wide range of battery retailers competing for your business.
Once you have bought your new battery, fit it carefully, remembering that the power output from even a modest car battery can delliver a lethal shock if handled incorrectly. If you are unsure, have a mechanic fit it for you.