- Yuasa Battery, Inc. Automobile Battery Charger User Manual

Battery Testing
Methods of Checking Battery Condition
State of Syringe Digital 5-Ball
Charge Hydrometer Voltmeter Hydrometer
100% Charged
w/Sulfate Stop 1.280 12.80v 5 Balls Floating
100% Charged 1.265 12.60v 4 Balls Floating
75% Charged 1.210 12.40v 3 Balls Floating
50% Charged 1.160 12.10v 2 Balls Floating
25% Charged 1.120 11.90v 1 Balls Floating
0% Charged less than 1.100 less than 11.80v 0 Balls Floating
POINTS TO REMEMBER
Use a voltmeter or hydrometer to test state of charge.
In extreme cold or heat, you’ll have to adjust hydrometer readings.
Battery can be tested with or without electrical load applied.
Unloaded testing is simplest.
Applying a load and reading voltage at battery is more accurate.
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A battery’s specific gravity changes with temperature.
Ideally, readings should be taken at 77°F. Is it really
going to matter if you’re off a couple of degrees one way
or another? Probably not. If you’re working somewhere
that’s uncomfortably hot or cold, it’s time to use the old
conversion factors: add .001 to the specific gravity read-
ing for each 3°F above 77°F or subtract .001 from the
specific gravity reading for each 3°F below 77°F. Cell
voltage can be found by adding .84 to the specific gravity.
Note, too, that YUASAs “Sulfate Stop,” a chemical addi-
tive that increases battery life by drastically reducing sul-
fate buildup, changes the specific gravity readings; they’ll
be higher than with ordinary batteries.
Test sealed VRLA types with a voltmeter or
multimeter. If the stabilized open circuit voltage is
below 12.5v, the battery needs charging. For a stabilized
open circuit reading, first allow the battery to remain in
an open circuit condition for at least 1 - 2 hours.
LOADED TESTING: There are two types of loaded tests
for motorcycle batteries. You’ll need a voltmeter or multi-
meter.
Low-load test: Basically, this means turning on the
bike’s lights and taking a voltage reading at the battery.
Remember, hook positive (+) to positive (+), negative (-) to
negative (-). The battery in a 12v system should have at
least 11.5v DC with the lights on. A 6v system should
have at least 5.75v DC. If voltage drops below these lev-
els, it’s time to charge.
High-rate discharge test: This is the best test of bat-
tery condition under a starting load. Use a load testing
device that has an adjustable load. Apply a load of three
times the ampere-hour rating.
At 14 seconds into the test, check battery voltage: a
good 12v battery will have at least 10.5v, and a good 6v
battery, at least 5.25v. If the reading’s low, charge.
There are two types of battery tests: unloaded and
loaded. An unloaded test is made on a battery without
discharging current. It’s simplest and most commonly
used. If you need a precise reading, loaded testing is the
answer. It’s more accurate.
UNLOADED TESTING: Check charge condition using
either a hydrometer or voltmeter. With a voltmeter,
voltage readings appear instantly to show the state of
charge. Remember to hook the positive lead to the
battery’s positive terminal, and the negative lead to the
negative terminal.
A hydrometer measures the specific gravity of each cell.
The specific gravity tells the degree of charge;
generally, a specific gravity of about 1.265 to
1.280 indicates a full charge. A reading of 1.230
to 1.260 indicates the battery should be charged before
testing. The chart below shows the charge level as
measured by syringe float hydrometer, digital voltmeter
and five-ball hydrometer.
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SECTION
Inspecting, Testing
and Charging