Basic Battery Terminology for Solar Power Systems

When reading about deep cycle solar batteries, here are some of the terms you might find used:

AGM: A type of lead acid battery which is known for being maintenance free.

AMP: Unit of measure for electrical current.

Capacity:  The amount of energy a battery can hold.

Current: The flow of electricity.

Days of Autonomy: The number of days a battery bank can provide energy for electrical loads before the batteries need to be recharged.

DC: Direct Current is the unidirectional (one way) flow of electric charge. Batteries and solar panels output DC current

Deep Cycle: A deep-cycle battery is a lead-acid battery designed to be regularly deeply discharged using much of its capacity.

Distilled Water: Water that has had most impurities removed by distillation, which involves boiling.

DoD:  Depth of Discharge refers to how deeply the battery has been discharged.

Electrolyte: In a battery, electrolyte is a gel or liquid medium that allows electricity to flow.

Flooded: Also referred to as Wet Cell. This is the most common type of lead acid battery. Flooded batteries require regular maintenance.

Hydrogen: A highly flammable gas that can be released when charging batteries.

Hydrometer: A tool used to measure the specific gravity within a flooded lead acid battery.

Specific Gravity: A density ratio between substances. Within a battery, specific gravity is a measurement of the current state of charge.

State of Charge (SoC): State of Charge refers to the percentage of a battery’s total energy capacity that is still available to discharge (use). It is loosely comparable to an automobile’s fuel tank, with 0% being empty and 100% being full.

Volt Meter: A tool to measure electrical volts.

VOLTS: The measure of the force that makes electricity move through a wire.