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.
Changing the connecting terminals to lead, the same material as the battery pole of a starter battery, will solve most corrosion problems. The lead within a battery is mechanically active. On discharge, the lead sulfate causes the plates to expand, a movement that reverses during charge when the plates contract again.