Ezgo Express S4 User Manual

MAINTENANCE
45
NOTICE: Do not perform a hydrometer test on a battery that has just been watered. The battery must go
through at least one charge and discharge cycle in order to permit the water to adequately mix with the elec-
trolyte.
The temperature of the electrolyte is important since the hydrometer reading must be corrected to 80° F (27° C). High
quality hydrometers are equipped with an internal thermometer that will measure the temperature of the electrolyte
and will include a conversion scale to correct the float reading. It is important to recognize that the electrolyte tempera-
ture is significantly different from the ambient temperature if the vehicle has been operated.
Using A Hydrometer
1. Draw electrolyte into the hydrometer and release it sev-
eral times to permit the thermometer to adjust to the
electrolyte temperature and note the reading. Examine
the color of the electrolyte. A brown or gray coloration
indicates a problem with the battery and is a sign that
the battery is nearing the end of its life.
2. Draw the minimum quantity of electrolyte into the
hydrometer to permit the float to float freely without con-
tacting the top or bottom of the cylinder.
3. Hold the hydrometer in a vertical position at eye level
and note the reading where the electrolyte meets the
scale on the float.
4. Add or subtract four points (.004) to the reading for
every 10° F (6° C) the electrolyte temperature is above
or below 80° F (27° C). Adjust the reading to conform
with the electrolyte temperature, e.g., if the reading indi-
cates a specific gravity of 1.250 and the electrolyte tem-
perature is 90° F (32° C), add four points (.004) to the
1.250 which gives a corrected reading of 1.254. Simi-
larly if the temperature is 70° F (21° C), subtract four
points (.004) from the 1.250 to give a corrected reading
of 1.246.
5. Test each cell and note the readings (corrected to 80° F
or 27° C). A variation of fifty points between any two cell
readings (example 1.250 - 1.200) indicates a problem
with the low reading cell(s).
As a battery ages the specific gravity of the electrolyte will
decrease at full charge. This is not a reason to replace the
battery providing all cells are within fifty points of each other.
Since the hydrometer test is in response to a vehicle exhibit-
ing a performance problem, the vehicle should be recharged
and the test repeated. If the results indicate a weak cell, the
battery or batteries should be removed and replaced with a
good battery of the same brand, type and approximate age.
Hydrometer Temperature Correction
°F °C
160 71
150 65
140 60
130 54
120 49
110 43
100 37
90 32
80 26
70 21
60 15
50 10
40 4
30 -1
20 -6
10 -12
+.032
+.028
+.024
+.020
+.016
+.012
+.008
+.004
0
-.004
-.008
-.012
-.016
-.020
-.024
-.028
+.030
+.026
+.022
+.018
+.014
+.010
+.006
+.002
-.002
-.006
-.010
-.014
-.018
-.022
-.026
EXAMPLE #1
ELECTROLYTE TEMPERATURE
Above 80 °F (27 °C)
AMBIENT TEMPERATURE
Above 80 °F (27 °C)
ELECTROLYTE TEMPERATURE
Above 90 °F (32 °C)
HYDROMETER READING 1.250
1.250 + .004 = 1.254
CORRECTED SPECIFIC GRAVITY
READING
EXAMPLE #2
ELECTROLYTE TEMPERATURE
Above 80 °F (27 °C)
AMBIENT TEMPERATURE
Above 80 °F (27 °C)
ELECTROLYTE TEMPERATURE
Above 70 °F (21 °C)
HYDROMETER READING 1.250
1.250 - .004 = 1.246
CORRECTED SPECIFIC GRAVITY
READING
ELECTROLYTE
TEMPERATURE

Ezgo Express S4 Specifications

General

Brand	Ezgo
Model	Express S4
Category	Electric Vehicles
Language	English