ELECTRICAL
10.24
CONVENTIONAL BATTERY
OCV - OPEN
CIRCUIT
VOLTAGE
TEST
Battery voltage should be checked with a digital
multitester. Readings of 12.6 volts or less require
further battery testing and charging. See charts and
Load Test on below.
NOTE: Lead-acid batteries should be kept at or near
a full charge as possible. Electrolyte level should be
kept between the low and full marks. If the battery is
storedor used in a partially chargedcondition, or with
low electrolyte levels, hard crystal sulfation will form
on the plates, reducing the efficiency and service life
of the battery.
CONVENTIONAL BATTERY
SPECIFIC GRAVITY
TEST
A tool such as a Battery Hydrometer (PN 2870836)
can be used to measure electrolyte strength or
specific gravity. As the battery goes through the
charge/discharge cycle, the electrolyte goes from a
heavy(moreacidic)stateat fullchargetoa light(more
water) state when discharged. The hydrometer can
measure state of charge and differences between
cells in a multi-cell battery. Readings of 1.270 or
greater should be observedin a fully chargedbattery.
Differencesofmorethan.025betweenthelowestand
highest cell readings indicate a need to replace the
battery.
Detail A
1.10
1.15
1.20
1.25
1.30
Battery Hydrometer (PN 2870836)
Continued on next page
OPEN CIRCUIT VOLTAGE
State of
charge
Conventional
Lead-acid
100%
Charged
75% Charged
50% Charged
25% Charged
0% Charged
12.60V
12.40V
12.10V
11.90V
less than 11.80V
SPECIFIC GRAVITY
State of
charge*
Conventional
lead-acid
100%
Charged
75% Charged
50% Charged
25% Charged
0% Charged
1.265
1.210
1.160
1.120
less than 1.100
*At80_F
NOTE: Subtract .01 from the specific gravity reading at 40_ F.
CONVENTIONAL BATTERY
LOAD
TEST
CAUTION: To prevent shock or component
damage, remove spark plug high tension leads
and connect securely to engine ground before
proceeding.
NOTE: Thistest canonly be performed on machines
with electric starters. This test cannot be performed
with an engine or starting system that is not working
properly.
Abatterymay indicateafullchargecondition in theOCV
test and the specific gravity test, but still may not have
the storage capacity necessary to properly function in
theelectricalsystem. For thisreason, a batterycapacity
or load testshouldbe conducted whenever poor battery
performance is encountered. To perform this test, hook
a multitester to the battery in the same manner as was
done in the OCV test. The reading should be 12.6volts
or greater. Engage the starter and observe the battery
voltage while cranking the engine. Continue the test for
15 seconds. During cranking the observed voltage
should not dropbelow 9.5 volts. If the beginningvoltage
is 12.6 volts or higher and the cranking voltage drops
below 9.5 volts during the test, replace the battery .
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