Testing The Battery - Monaco Cayman 2005 Owner's Manual

Check the battery connections for tightness and corrosion. If corrosion is found, disconnect the
cables (mark cable locations) and carefully clean them with a mild solution of baking soda and water, or
an aerosol product specifically designed for battery maintenance. Do not allow cleaning solution to seep
into the battery and damage the electrolyte balance. Use water to rinse the top of the battery and sur-
rounding area when done. Carefully hook the cables back to the battery. The battery cable to battery ter-
minal connections should be metal to metal. Coat the terminals with petroleum jelly or an anti-corro-
sion grease.
WARNING:
Liquid lead acid batteries produce hydrogen gas while being charged. This is highly explo-
sive. Do not smoke around batteries and keep all source of ignition or flames away from
batteries. The hydrogen gas may explode resulting in fire, personal injury, property
damage or death.
A battery can be tested and monitored several ways. The Monitor Panel
on the Systems Control Center in the hallway shows the voltage of the house
batteries at a quick glance. The most efficient way of testing the LLA bat-
teries is to check the electrolyte solution using a hydrometer.
Hydrometers are available in different types, such as cylinder gradua-
tion (shown here) or floating ball types. Hydrometers can be purchased
from most auto parts stores. The hydrometer tests the battery electrolyte
solution, measured in specific gravity. Distilled water has a specific
assigned gravity of 1,000. The hydrometer is calibrated to this mark.
Pure sulfuric acid has a specific gravity reading of 1,840. The acid is
1.84 times heavier than water. The electrolyte solution is about 64% water
to 36% acid (fully charged battery). Hydrometers with cylinder graduation
are graphed and the exact state of specific gravity can be determined.
Temperature and recent battery activity (charging or discharging) affect
the hydrometer readings. It is best to check the battery when it has been
"at rest" for at least three hours, although readings taken at other times
will give a "ballpark" figure. When using the hydrometer, draw the elec-
trolyte solution up into the tube. Allow the hydrometer to attain the same
temperature as the electrolyte solution. Note the reading for that cell.
Complete the same test for the rest of the cells on that battery bank.
The hydrometer is calibrated at 80° F. Temperature affects the hydrometer readings. The higher the elec-
trolyte temperature, the higher the specific gravity reading. The lower the temperature, the lower the specific
gravity reading. Add or subtract four points for each 10° variance from the 80° F chart. Readings between
cells should not vary more than 50 points.
If one cell in a particular battery bank being tested is at a 50% state of charge while the others are indi-
cating a full charge, charge only that battery to see if the low cell will come up. At the same time, do not
over charge the "healthy" cells.
Cayman 2005
Hydrometer (Cylinder Type)
testing a LLA type battery.
Electrical Systems - House --- Section 8

Testing the Battery

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