Blood pressure is usually expressed in terms of the systolic pressure (maximum during one heart beat) pressure over diastolic pressure (minimum in between two heart beats) and is measured in millimeters of mercury (mmHg), above the surrounding atmospheric pressure (considered to be zero for convenience).
Corrosion on the terminals is due to hydrogen gas being released from the acid in the battery. It mixes with other things in the atmosphere under the hood and produces the corrosion you see on the terminals. Generally, if the corrosion is occurring on the negative terminal, your system is probably undercharging.
What is Battery Sulfation? Sulfation, a build-up of lead sulfate crystals, is the number one cause of early failures of lead-acid, sealed AGM or flooded (wet cell-filler caps) batteries. A sulfated battery can lead to: 1  loss of cranking power. 2  longer charging times. 3  excessive heat build-up leading to boil out. 4  shorter running times between charges. 5  dramatically shorter battery life.