Maintaining a battery
Most modern, sealed VRLA automotive batteries are designated ‘Maintenance Free’, which denotes that they cannot be topped up with distilled water. The MOT stipulates that the battery should be secured firmly, so check the condition of the battery tray and clamps, while ensuring that the battery is clean and dry and that its vents are not obstructed. Validate the tightness of the terminals and wiring condition, too. While coating the terminals and posts with petroleum jelly is not strictly necessary on modern batteries, it does no harm.
Yuasa advises that a battery is a live product: if it is not fed, it will die. So, ensure that it is charged adequately, especially if your car makes short runs only. As the increasing internal resistance of an ageing battery can fool a conventional alternator to undercharge it, you should disconnect the battery leads and treat the battery to a refresher charge every three months.