5. Grooved side of separators placed against negatives in cells giving the low readings.
6. Separator left out, cracked separator used, hole worn through separator by buckled plate or swollen negatives, or separators in some cells and new ones in others.
7. Old plates used in some cells and new ones in others.
8. Impurities in cells showing low gravity.
9. Shorted cell, due to plates cutting through separators.
10. Cracked jar.
11. Oil some of the older cars a three wire lighting system was used. If the lights are arranged so that more are connected between one of the outside wires and the center, than between the other outside wire and the center, the cells carrying the heavier lighting load will show low gravity.
12. On some of the older cars, the battery is made of two or more sections which are connected in series for starting and in parallel for charging. Oil such cars the cells in one of the sections may show lower gravity than other cells due to longer connecting cables, poor connections, corroded terminals, and so on. Such a condition AN-ill often be found in the old two section Maxwell batteries used previous to 1918.
High Gravity
This is a condition in which the hydrometer readings would indicate that a battery is almost or fully-charged, but the battery may fail to operate the starting motor. If the lights are burning while the starting switch is closed, they will become very dim. The gravity readings may be found to be above 1.300.