R.P.S. Corporation MAGNUM series, Руководство по обслуживанию

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Magnum Service Manual V1.0
11
11-6
BATTERY SYSTEM
The state-of-charge of a lead acid battery can be determined by the specific gravity of the
electrolyte (its weight compared to water). The specific gravity can be measured directly
with a hydrometer or determined by the stabilizing voltage.
A hydrometer is a bulb-type syringe which will extract electrolyte from a cell. A glass float
or a plastic disk in the hydrometer body is calibrated to read in terms of specific gravity. A
common range of specific gravity used on these floats is 1.160 to 1.325. Do not assume a
battery will not take a charge because you have been charging it for a while and the float
will not rise. The battery may have been fully discharged and will require considerable
charging time before reaching the minimum specific gravity on the float.
The lower the float sinks in the electrolyte, the lower its specific gravity. The proper way to
read a hydrometer is to dray electrolyte into the body of the hydrometer while holding it ver-
tically so the float is not rubbing on the side of it Draw an amount of acid into the body so
the that with the bulb fully expended, the float will be lifted free not touching either side, the
top or the bottom. Your eye should be level with the surface of the liquid in the hydrometer
body. Disregard the curvature of the liquid where the surface rises against the float stem
and the barrel due to surface tension. Keep your hydrometer and it’s float clean. Check
them frequently for cracks.
The following table illustrates typical specific gravity values for a cell in various stages of
charge with corresponding voltage readings.
OPEN CIRCUIT
VOLTS
STATE OF
CHARGE
HYDROMETER
READING
12.65 100% 1.260 or more
12.45 75% 1.225 - 1.260
12.24 50% 1.190 - 1.225
12.06 25% 1.120 - 1.190
11.89 Totally Discharged 1.120 or less