Rolls 16 CH 25P, User Manual

Page: 11 / 28

8 9
shorten the life of the battery considerably. Undercharge is indicated by a decrease in
specific gravity readings.
Overcharge is commonly identified by faster and/or excessive water loss due to
off-gassing, dark electrolyte due to burning oxide paste or very high specific gravity
readings.
The correct float voltage will charge and maintain the battery at full state-of-charge.
This is determined by two factors – operating temperature and locomotive work
schedule.
When properly installed, a temperature sensor regulates the float voltage,
compensating for changes in cell temperature. See Figure 1 – Temperature Sensor for
instructions.
RECOMMENDED FLOAT VOLTAGE
The recommended float voltage per cell at varying ambient temperatures are as
follows:
TEMPERATURE
FLOAT VOLTAGE
VPC 8 VOLT 32 VOLT
GREATER THAN 27°C (80°F) 2.25-2.30 VPC 9.0-9.20V 36.0-36.8V
10°C (50°F) to 27°C (80°F) 2.30-2.33 VPC 9.20-9.32V 36.8-37.28V
LESS THAN 10°C (50°F) 2.33-2.38 VPC 9.32-9.52V 37.28-38.08V
The effect of locomotive work schedule on the correct float voltage is often determined
by usage and experience. If the battery is used for starting frequently, such as an
auto start/stop where the locomotive may be repeatedly started to warm the engine
when not be in use, the float voltage should often be set at the higher end of the range
indicated at the appropriate temperature; similarly, for infrequent battery usage, the
operating or float voltage should be set at the lower end of the range.
Adjustments in float voltage may be necessary from season to season and in situations
where the batteries have become sulfated.
NOTE: It is recommended that float voltage regulator adjustments be made while the
engine is at operating speeds.