Batteries last longer when stored in a charged state

Changing a hp pavilion dv7 battery When changing a battery, battery manufacturers recommend disconnecting the negative ground connection first to prevent accidental short-circuits between the hp pavilion dv7 battery terminal and the vehicle frame. Conversely the positive cable is connected first. A study by the National Highway Traffic Safety Association estimated that in 1994 more than 2000 people were injured in the United States while working with automobile batteries. The majority of automotive lead-acid batteries are filled with the appropriate electrolyte solution at the manufacturing plant, and shipped to the retailers ready to sell. Decades ago, this was not the case. The retailer filled the battery, usually at the time of purchase, and charged the battery. This was a time-consuming and potentially dangerous process. Care had to be taken when filling the hp pavilion dv7 battery with acid, as acids are highly corrosive and can damage eyes, skin and mucous membranes. Fortunately, this is less of a problem these days, and the need to fill a battery with acid usually only arises when purchasing a motorcycle or ATV battery. Freshness Because of 'sulfation', lead-acid batteries stored with electrolyte slowly deteriorate. Car batteries are date coded to ensure installation within one year of manufacture. In the United States, the manufacturing date is printed on a sticker. The date can be written in plain text or using an alphanumerical code. The first character is a letter that specifies the month (A for January, B for February and so on).[7] The letter 'I' is skipped due to its potential to be mistaken for the number 1. The second character is a single digit that indicates the year of manufacturing (for example, 6 for 2006). When first installing a newly purchased battery a 'top up' charge at a low rate with an external hp pavilion dv7 battery charger (available at auto parts stores) may maximize battery life and minimize the load on the vehicle charging system. Failure Common battery faults include: Shorted cell due to failure of the separator between the positive and negative platesShorted cell or cells due to build up of shed plate material below the plates of the cell.Broken internal connections due to corrosion.Broken plates due to vibration and corrosionLow electrolyte level Cracked or broken case Broken terminals.Sulfation after prolonged disuse in a low or zero charged state.Corrosion at the hp pavilion dv7 battery terminals can prevent a car from starting due to electrical resistance. The white powder sometimes found around the battery terminals is usually lead sulfate which is toxic by inhalation, ingestion and skin contact. The corrosion is caused by an imperfect seal between the plastic battery case and lead battery post allowing sulfuric acid to react with the lead hp pavilion dv7 battery posts. The corrosion process is also expedited by over charging. Corrosion can also be caused by factors such as salt water, dirt, heat, humidity, cracks in the battery casing or loose battery terminals. Inspection, cleaning and protection with a light coating of dielectric grease are measures used to prevent corrosion of hp pavilion dv7 battery terminals. Sulfation occurs when a battery is not fully charged. The longer it remains in a discharged state the harder it is to overcome sulfation. This may be overcome with slow, low-current (trickle) charging. Sulfation is the formation of large, non-conductive lead sulfate crystals on the plates; lead sulfate formation is part of each cycle, but in the discharged condition the crystals become large and block passage of current through the electrolyte. The primary wear-out mechanism is the shedding of active material from the hp pavilion dv7 battery plates, which accumulates at the bottom of the cells and which may eventually short-circuit the plates.