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.
Wire sized to supply voltage at 240-volt levels will be roughly half the size it needs to be to safely carry the amount of electrical current required at 120 volts. We see this major flaw on brand-new boats, so beware. Exposure to salt water is a major cause for corrosion at buss bars and electrical termination points.