It is important to note that when the battery of a vehicle is disconnected, the radio code, on-board computer settings and clock settings are lost. It is therefore advisable to obtain the radio code in advance. After reconnecting it, you will not be able to get sound through the radio until you input the correct code. One should avoid tools bridging battery terminals because this may cause short circuits, sparks and even personal injuries. Due to explosive gases emitted by batteries for example no smoking, open flames or sparks within close proximity to a battery are allowed hence strictly discouraged. Properly securing it with hold-down devices can prevent cracking, acid leakage and accelerated discharge. It should also be regularly visually examined for cracks, leakages and corrosion on its case if any since this might lead to a bad one that has to be rectified immediately. Electrolyte levels in unsealed batteries need periodic checkups either by inspection through case or removing cell caps as well as topped up with distilled water in some cases. The battery cables and terminals must remain free from corrosion while the top of the battery must always be kept clean to prevent discharge. This helps maintain charge in vehicles which are not frequently operated and for those having additional accessories like radios; they may require negative battery cable disconnection during storage periods. In order not reduce its lifespan unnecessarily do not discharge recharge your battery without necessity doing so will shorten it's life considerably . Distilled water should refill each cell up to level indicated by split ring (each) or outside of case (a line). Battery terminals should be cleaned annually so that wires brush plus dielectric grease can be used instead of cleaning off rusts right away after disconnecting negative cable opening positive clamp first Will replacing damaged cables required testing their condition because damaged cables, Men of great importance in changing exposed cells include activities such as ventilation, evacuation before cleaning necessary supplies including protective clothing that includes goggles gloves apron For instance, the E30 series has its battery in the right side engine compartment, while the E36 series has it in the luggage compartment and Z3 models have it centrally placed. When replacing a battery, it is necessary to choose one having enough cold cranking amps equal or even greater than that of the original battery by considering the wire aging as well as increased electrical resistance of older vehicles. In this case, you should open your car trunk, unplug negative and positive cables from it, take away both batteries with their brackets along with radio recoding and reinitialization of windows if they are electrically operated and possess finger jams.