Looking after your battery

Posted on December 9th, 2014 by Rob Marshall

batteryAlthough we have been blessed with a mild winter, so far this year, my contacts in the parts supply business inform me that they are stocking up on car batteries, bracing themselves for the first snap of cold weather, should it arrive.

As the season last year was relatively mild overall, throughout the UK, elderly batteries have not been exposed to the much harsher cold weather, conditions in which an older item might struggle to summon up sufficient energy to start an engine.

However, because almost all conventional car batteries are sold as ‘maintenance free’, owners presume that they can be fitted and forgotten. This is not the case. Car batteries prefer to be kept fully-charged and will be damaged permanently, if they are kept at anything below this level. You might not notice that anything is wrong with your battery, because it may appear to be operating perfectly satisfactorily, but the damage is still being caused.

Therefore, charging the battery, using a mains-powered trickle charger (I will discuss the new generation of smart chargers in a future blog), is a wise idea. Depending on your charger and car model, this can be performed without disconnecting the battery from the car. Newer models, equipped with battery monitoring ECUs, tend to require the negative pole of the battery charger to be attached to an earth point on the car body and not directly to the battery terminal. Always consult your car manufacturer, if you are uncertain. In addition, many cars have a battery disconnection procedure that will allow the various computers and ECUs to power down, prior to the power being cut-off. To complicate things further, some latest cars require a new battery to be coded to the vehicle, which inevitably, increases the cost of renewal.

More in-depth battery advice is here but we have come across motorists recently, who are trying to economise, by replacing a failed Absorbent Glass Matt (AGM) battery with a cheaper older-style flooded acid battery. AGM batteries tend to be fitted to high-specification models possessing stop-start and regenerative braking features, and their discharge and recharging characteristics differ considerably to those of the more traditional flooded acid battery.

If you fit an incompatible battery type to such a car, not only will its charging system be incapable of replenishing the battery charge but the stop-start system will also fail to operate correctly, which is likely to reduce the fuel efficiency savings that the technology offers. You might also void any remaining vehicle warranty.