The importance of winter battery charging

While 12-volt car batteries face challenges throughout the year, failure tends to be more prevalent during winter, when it cannot perform in a weakened state. This explains why the majority of breakdown callouts during this season are caused by battery issues.

With replacement lead-acid batteries increasing in cost, it is worth making them last for as long as possible. This blog will help you to understand more about car batteries and how to maintain them. While decent breakdown cover, with home-start assistance, will have your back, even the finest support cannot prevent the inconvenience factor.

What causes car batteries to deteriorate?

While most conventional flooded car batteries are rated at 12 volts, expect a fully-charged battery to achieve 12.6 volts. Should the voltage (i.e. the State of Charge) fall below 12.4 volts, internal chemical reasons occur (sulphation) that, ultimately, reduce the battery's capacity. The chemistry within lead-acid batteries means that they last longer, when kept charged fully. Therefore, this should be your priority.

How do I make my car battery last longer?

The main task is to ensure that the battery charge level is above 12.4 volts. You can measure this across the battery terminals, with an inexpensive voltmeter. To achieve an accurate reading, do not measure voltage after a journey, because you are likely to get a misleading surface charge measurement. Also, ensure that the car is not consuming electrical power, when you take your measurement, as this will result in an artificially low reading.

Therefore, test battery voltage after the car has been left standing for at least six hours and at least five minutes after the ignition has been switched off and all doors have closed.

Ensure also that your car charging system is in good order. In most cases, this means ensuring that the alternator's drive belt is intact, the battery terminal connections are clean and no low-voltage warning messages have appeared on the instrument cluster.

Can I recharge my battery with a charger?

It is not appreciated often that even the car's charging system can struggle to recharge a car battery fully. This is especially the case, with repetitive short journeys that last under 20 minutes. The battery suffers from gradual voltage walkdown, which the owner might not even notice, because the engine can still be started. However, in a low-voltage condition, the battery will deteriorate internally, resulting in a reduction in capacity to such an extent that it will be unable to deliver the required power, especially in cold weather.

The solution is to charge the battery, with a mains-powered charger. This is not easy, unless you have off-street parking, because you are not permitted to lay electrical cabling across a pavement.

What battery charger should I use?

With most modern batteries being sealed and, with the advent of batteries that are designed with stop-start systems, we do not recommend that you use old-fashioned trickle chargers on modern cars. While they reduce the charging current, as the battery voltage increases, they do not switch off completely. The result is over-charging, which risks shortening battery life.

Modern smart chargers not only switch off power to the battery, when it is charged fully, but they also possess algorithms to promote more effective charging and can

even reverse a degree of damage, caused by low-voltage conditions. They also possess programmes that can recharge sophisticated and expensive Absorbent Glass Mat batteries, used on many of today's start/stop and Mild Hybrid (MHEV) cars. Prices for modern smart chargers have come down significantly, and a budget of £60-£150 should net you a good-quality example from a reputable brand.

How do I connect a smart charger to my car?

We have found that advice differs. Some cars can have their batteries recharged, without being disconnected from the vehicle. Yet, other cars are more fussy, especially those with battery monitoring systems. Consult your owners' handbook, first. Should you be unsure, enquire with your main dealer.

What to do about it 

Keep up to date with the latest news from GEM Motoring Assist at:

X: @motoringassist

Facebook: @gemmotoringassist

Instagram: @gem_motoringassist

LinkedIn: @gem-motoring-assist

GEM Motoring Assist is a members’ motoring and road safety organisation in the UK. Our aim is to keep our members on the move… whether that’s through our breakdown recovery service or our motoring and road safety expertise.

Join GEM for simple and straightforward, all-inclusive personal breakdown cover.