(2) Disconn ect and isolate the battery nega tive
cable. Connect the ba tter y ch arger leads. Some bat-
tery chargers a re equipped wit h polarity-sensin g cir-
cuitry. This circuitr y prot ects the battery charger and
the batt ery from being da maged if they ar e improp-
erly connect ed. If th e ba tter y st ate-of-ch arge is t oo
low for th e polar ity-sensing circuitr y to det ect, the
batt ery charger will not oper ate. This ma kes it
appear that th e bat tery will not accept charging cur-
rent . See t he in st ructions provided by the ma nufa c-
turer of the batt ery charger for deta ils on h ow to
bypass the polarity-sensing circuitry.
(3) Batt ery chargers var y in the amount of volta ge
and current th ey pr ovide. The am ount of time
required for a bat tery t o accept m easurable cha rging
curren t at va riou s volta ges is shown in the Char ge
Rate Table. If t he charging curren t is still n ot mea -
su rable at t he end of the cha rging tim e, the battery
is fault y and m ust be repla ced. If th e charging cur-
rent is measurable dur ing th e cha rging time, the ba t-
tery may be good and the cha rging sh ould be
complet ed in the normal manner.
CHARGE RATE TABLE
Voltage Hours
16.0 volts maximum up to 4 hours
14.0 to 15.9 volts up to 8 hours
13.9 volts or less up to 16 hours
CHARGING TIME REQUIRED
The time requir ed t o char ge a battery will vary,
depending upon th e following fact ors:
• Battery Capacity - A complet ely discha rged
heavy-dut y battery requir es twice th e ch arging t ime
of a small capacity battery.
• Te m p e r a t u re - A lon ger t ime will be n eeded to
charge a ba tter y at -18° C (0° F ) t han at 27° C (80°
F). Wh en a fa st bat tery cha rger is connected t o a cold
batt ery, the curren t a ccepted by the battery will be
very low at first. As th e battery wa rms, it will a ccept
a higher cha rging curr ent rate (amper age).
• Ch a rg e r Ca p a c i ty - A batt ery charger that
su pplies only five am peres will require a lon ger
charging time. A batt ery ch arger tha t su pplies
twenty am peres or mor e will requir e a shorter cha rg-
ing time .
• Sta te -Of-Ch a rg e - A completely dischar ged bat-
tery requir es mor e cha rging time than a partia lly
dischar ged bat tery. Electrolyt e is nea rly pure water
in a completely discha rged battery. At first, the
charging curr ent (ampera ge) will be low. As the bat-
tery charges, the specific gravity of the electrolyte
will gr a du a lly r ise.
The Bat tery Ch arging Time Table gives an in dica-
tion of th e tim e requir ed to ch arge a typical battery
at room temper atur e based upon the batt ery st ate-of-
charge an d t he cha rger capacity.
BATTERY CHARGING TIME TABLE
Charging Amper-
age
5 Amps
10
Amps
20 Amps
Open Circuit Volt-
age
Hours Charging @ 21° C (70°
F)
12.25 to 12.49 6 hours 3 hours 1.5
hours
12.00 to 12.24 10 hours 5 hours 2.5
hours
10.00 to 11.99 14 hours 7 hours 3.5
hours
Below 10.00 18 hours 9 hours 4.5
hours
STANDARD PROCEDURE - OPEN - CIRCUIT
VOLTAGE TEST
A battery open-cir cuit voltage (no load) test will
sh ow the a pproxima te state-of-charge of a bat tery.
This test can be used in pla ce of th e hydrom eter test
when a hydrometer is not ava ilable, or for mainte-
nance-fr ee batteries wit h non-remova ble cell ca ps.
Before proceeding with th is t est , completely charge
the battery (Refer to 8 - ELECTRICAL/BATTERY
SYSTEM/BATTERY - STANDARD PROCEDURE).
(1) Before measur ing the open-cir cuit voltage, the
su rface ch arge must be r emoved fr om the ba tter y.
Turn on the hea dlamps for fifteen seconds, then
allow up to five minut es for the battery voltage to
stabilize.
(2) Disconn ect and isolate both ba ttery cables, n eg-
ative ca ble first.
Fig. 4 VOLTMETER ACCURATE TO 1/10 VOLT
VA BATTERY SYSTEM 8F - 9
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