Chevrolet 30 Series 1967 Service Manual page 353

EMERGENCY BOOST CHARGING
In cases where the Battery is not sufficiently charged
to crank the engine, an emergency boost charge may be
applied as a temporary expedient in order to crank the
engine. The Emergency Boost Charge method consists
of charging at a 40 to 50 ampere rate for a period of
one-half hour.
It should be particularly noted that the Emergency
Boost Charge will not necessarily restore the Battery
to a useful state of charge for continued service. After
an emergency boost charge, failure to charge the Bat­
tery further, either by a long uninterrupted driving
period or by the Fast Charge or Slow Charge method,
may result in failure to crank the engine the next time
cranking is attempted. A Battery should never be con­
demned on the basis of failure to crank the engine after
an emergency boost charge.
boost charge may put enough energy into the Battery
to crank the engine once, further charging usually is
necessary in order to create a sufficient reserve to
crank a second and third time.
12 VOLT BATTERY
SUGGESTED CHARGING RATES
(100 Amp/hr or Less Capacity)
Type
of Charge
Boost Charge for
20 Minutes
Light Load Test
Slow Charge
1-1/2 Hours
Fast Charge
Emergency Quick
30 Minutes
Boost
Dry Charge
10 Minutes
Warm-up Boost
BATTERY TESTING PROCEDURES
Testing procedures are used to determine whether
the Battery is (1) good and usable, (2) requires re ­
charging or (3) should be replaced. Analysis of Battery
conditions can be accomplished by performing a visual
inspection. Instrument Test and the full charge hydro­
meter test.
1. VISUAL INSPECTION
The first step in testing the Battery should be a visual
inspection, which very often will save time and expense
in determining Battery condition.
• Check the outside of the Battery for a broken or
cracked case or a broken or cracked cover. If
any damage is evident, the Battery should be
replaced.
• Note the electrolyte level. Levels that are too
low or too high may cause poor performance, as
Although an emergency
Length Charging
Rate
of Time
50 Amps
4 Amps
24 Hours
40-50 Amps
40-50 Amps
15 Amps
covered in the
Servicing" .
• Check for loose cable connections, and for evi­
dence of corrosion as covered in section entitled
" Periodic Servicing" . Correct as required before
proceeding with tests.
2. INSTRUMENT TEST
A number of suppliers have approved testing equipment
available. These testers have a programmed test proce­
dure consisting of a series of timed discharge and charge
events, requiring approximately
will determine the condition of the Battery with a high
degree of accuracy. When using these testers, the pro­
cedure recommended by the tester manufacturer should
be followed. Batteries should not be charged prior to
testing or doing so may alter the test results. If a
tester is not available for testing, the "Specific Gravity
Cell Comparison Test" may be used or an alternate
method, but with a sacrifice in testing accuracy.
3. FULL CHARGE HYDROMETER TEST
This test should be used only on Batteries which test
good with testing equipment or "Specific Gravity Cell
Comparison T est" but which subsequently fail in service.
• Remove the Battery from the vehicle, and adjust
the electrolyte level as necessary, by adding color­
less, odorless, drinking water.
• Fully charge the Battery at the Slow Charging
rate as covered in the section entitled " Battery
Charging" .
• Measure the specific gravity of the electrolyte in
each cell and interpret as follows:
Hydrometer Reading
charge hydrometer readings less than 1.230 cor­
rected for temperature indicate the Battery is
defective and should be replaced.
Hydrometer Readings Above 1.310—Full charge
hydrometer readings above 1.310 corrected for
temperature indicate that the cells have been im­
properly filled (activation) or improperly serviced.
Poor service and short Battery life will result.
SPECIFIC GRAVITY READINGS
A hydrometer can be used to measure the specific
gravity of the electrolyte in each cell (fig. 7b).
The hydrometer measures the percentage of sulphuric
acid in the battery electrolyte in terms of specific
gravity. As a battery drops from a charged to a dis­
charged condition, the acid leaves the solution and enters
the plates, causing a decrease in specific gravity of
electrolyte. An indication of the concentration of the
electrolyte is obtained with a hydrometer.
When using a hydrometer, observe the following points:
1. Hydrometer must be clean, inside and out, to insure
an accurate reading.
2. Hydrometer readings must never be taken immedi­
ately after water has been added. The water must be
thoroughly mixed with the electrolyte by charging
for at least 15 minutes at a rate high enough to cause
vigorous gassing.
3. If hydrometer has built-in thermometer, draw liquid
into it several times to insure correct temperature
before taking reading.
ENGINE-ELECTRICAL 6Y-5
section entitled " Periodic
to 3 minutes, that
2
Less Than 1.230—Full
CHEVROLET TRUCK SERVICE M ANUAL