Chevrolet CHEVY VAN G10 SERIES Service Manual page 216

W att R ating 5 A m peres
Below 2450
10 Hours
2450-2950
12 Hours
Above 2950
15 Hours
♦Initial rate for constant voltage taper rate charger.
T o avoid dam age, charging rate m ust be reduced or tem p o r­
arily h alted if:
1. E lectrolyte tem perature exceeds 125°F .
2. V iolent gassing or spewing o f electrolyte occurs.
B attery is fully charged w hen over a tw o hour period at a low
TEST PROCEDURES
T estin g p ro c e d u re s a re u sed to d eterm in e w h eth e r th e
B a tte ry is ( 1 ) g o o d a n d u sab le, ( 2 ) re q u ire s rech arg in g
o r ( 3 ) sh o u ld b e rep la ce d . A n aly sis of B a tte ry cond itio n s
c a n b e ac co m p lish e d b y p e rfo rm in g a V isu a l In sp ectio n ,
Specific G ra v ity T est, In stru m e n t T e st a n d L o a d T est.
R e fe r to T e s t P ro c e d u re s C h a rt at th e en d o f this section.
VISU A L INSPECTION
The first step in testing the B attery should be a visual
inspection, w hich very o ften will save tim e an d expense in
determ ining B attery condition.
• Check the outside o f the B attery for a b ro ken or cracked
case or a broken or cracked cover. I f any damage is
evident, the B attery should be replaced.
• N ote th e electrolyte level. Levels th a t are to o low or too
high may cause p o o r perform ance, as covered in the
section en titled "Periodic Servicing."
• Check for loose cable connections, and for evidence o f
corrosion as covered in section en titled "Periodic Servic­
ing." C orrect as required before proceeding w ith tests.
SPECIFIC G R A V IT Y READINGS
A h y drom eter can be used to m easure the specific gravity
o f th e electrolyte in each cell (Fig. 7b).
T he h y drom eter m easures the percentage o f sulphuric acid
in the b attery electrolyte in term s o f specific gravity. As a
b attery drops from a charged to a discharged co ndition, the
acid leaves the solution and enters th e plates, causing a
decrease in specific gravity o f electrolyte. An indication o f the
concentration o f the electrolyte is o btained w ith a hy d ro m ­
eter.
When using a hydro m eter, observe the following points:
1. H ydrom eter m ust be clean, inside and o u t, to insure an
accurate reading.
2. H ydrom eter readings m ust never be taken im m ediately
after w ater has been added. The w ater m ust be
thoroughly m ixed w ith the electrolyte by charging for at
least 15 m inutes at a rate high enough to cause vigorous
gassing.
CHARGING GUIDE
R ecom m ended R ate* and Tim e for Fully Discharged C ondition
10 Amperes 20 Amperes
5 H ours
2-1/2 Hours
6
Hours 3 Hours
7-1/2 H ours 3-1/4 Hours
30 Amperes
2 H ours
2 Hours
2 H ours
charging rate in am peres all cells are gassing freely and no
change in specific gravity occurs. F o r the m ost satisfactory
charging, the low er charging rates in am peres are recom ­
m ended.
Full charge specific gravity is 1.260-1.280 corrected for
tem perature w ith electrolyte level at split ring.
3. If h y d ro m eter has built-in therm om eter, draw liquid in to
it several tim es to insure correct tem perature before
taking reading.
4. H old h y d ro m eter vertically and draw in just enough
liquid from b attery cell so th a t float is free floating. H old
h ydrom eter a t eye level so th a t flo at is vertical and free
o f o u ter tu b e, th en take reading at surface o f liquid.
Disregard the curvature w here the liquid rises against
float stem due to surface tension.
5. Avoid dropping b attery fluid on car or clothing as it is
extrem ely corrosive. A ny fluid th a t drops should be
w ashed o ff im m ediately w ith baking soda solution.
The specific gravity o f the electrolyte varies n o t only w ith
the percentage o f acid in th e liquid b u t also w ith tem perature.
As tem perature increases, the electrolyte expands so th a t the
specific gravity is reduced. As tem p eratu re drops, the electro­
lyte co n tracts so th a t th e specific gravity increases. Unless
these variations in specific gravity are taken in to account, the
specific gravity o btained b y th e h y d ro m eter m ay n o t give a
tru e indication o f th e co n cen tratio n o f acid in the electrolyte.
A fully charged B attery will have a specific gravity reading
o f approxim ately 1.270 at an electrolyte tem perature o f 80°F .
If the electrolyte tem perature is above or below 8 0 °F .,
additions or subtractions m ust be m ade in order to o b tain a
h y d ro m eter reading corrected to the 80° F . standard. F or every
10° above 8 0 °F ., add fo u r specific gravity p oints (.004) to the
h ydrom eter reading. Exam ple: A h y d ro m eter reading o f
1.260 at 110°F. w ould be 1.272 corrected to 80°F'., indicating
a fully charged B attery. F o r every 10° below 8 0 °F ., subtract
fo u r points (.002) from th e reading. E xam ple: A hydrom eter
reading o f 1.272 at 0 °F . w ould be 1.240 corrected to 8 0 °F .,
indicating a partially charged B attery.
SPECIFIC G R A V IT Y CELL COMPARISON TEST
This test may be used w hen an in stru m en t tester is n ot
available. T o perform this test m easure th e specific gravity of
each cell, regardless o f state o f charge, and in te rp re t th e results
as follows:
• I f specific gravity readings show a difference betw een the
highest an d low est cell o f .050 (5 0 points) or m ore, the
B attery is defective an d should be replaced.
ENG INE E LEC TR IC A L 6Y-5
40 Amperes 50 Amperes
1-1/2 Hours
1-3/4 Hours
1-1/2 Hours
C H E V Y V A N SH O P M A N U A L