The 1-ball model

It will provide a bright green indication if the battery is fully charged,

a dark indication if the battery is discharged, and a clear and bright indication if the electrolyte level is low.

The 2 Balls model

It will provide a bright green indication if the battery is charged, a clear and bright indication if the battery is discharged, red indication if the electrolyte level is low.

Advantages:

 Determines the battery cavity at a glance.

 Basing on specific gravity, indicates stable charging state

Provides temperature compensation to assure accurate readings of battery temperature.

Indicate a low electrolyte level.

 Reduces the need for OCV (Open Circuit Voltage) testing, thereby saving time.

 Reduces customer warranty claims.

Improves end-user satisfaction.