Power Products ALPHA C-25 Operating Manual

www.power-products.com

ALPHA C-20/25

BATTERY CHARGER

OPERATING MANUAL

Power Products Inc. • 27 Pamaron Way, Bldg. E • Novato • CA 94949

Tel: [phone] • Fax: [phone]

www.power-products.com

TABLE OF CONTENTS

1. SYSTEM OVERVIEW ...................................................... 3

1.1 SYSTEM OVERVIEW ........................................................... 3

1.2 DISPLAYS AND CONTROLS ................................................ 3

2. INSTALLATION .............................................................. 6

2.1 LINE VOLTAGE .................................................................... 6

2.2 TERMINALS ......................................................................... 6

2.3 SPACE REQUIREMENTS .................................................... 6

3. OPERATING GUIDE ....................................................... 7

3.1 CHARGE CHARACTERISTICS ............................................ 7

3.2 CHARGING METHODS ................................ ........................ 8

3.3 PREPARATION FOR CHARGING ........................................ 9

3.4 VERIFY END VOLTAGE ..................................................... 10

3.5 CHARGE TIME ................................................................... 11

4. CALIBRATION AND MAINTENANCE .......................... 15

4.1 OVERVIEW OF CALIBRATION ........................................... 15

4.2 SHUNT VERIFICATION ...................................................... 16

4.5 OPERATING RANGES ....................................................... 16

4.6 MAINTENANCE .................................................................. 17

5. TROUBLSHOOTING ..................................................... 18

6. SPECIFICATIONS ......................................................... 19

APPENDIX A - BATTERY OVERVIEW .............................. 20

CLASSES OF BATTERIES .......................................................... 20

SECONDARY BATTERIES .......................................................... 20

LEAD-ACID BATTERIES, VENTED OR VRLA ............................. 20

NICKEL-CADMIUM BATTERIES ................................................. 21

DEFINITIONS .............................................................................. 21

WARRANTY ....................................................................... 22

CERTIFICATION OF CALIBRATION ................................. 23

1. SYSTEM OVERVIEW

1. SYSTEM OVERVIEW

1.1 SYSTEM OVERVIEW

The Alpha C-25 Charger is a self-contained unit for charging of
rechargeable batteries. It has been designed to charge one or two batteries
of the same voltage rating simultaneously, to a combined maximum of 25
amperes. At 40 lbs. and 15 by 5 ¾ inches (381 by 146mm) the C-25 takes
minimal space and can easily be moved to add flexibility to the work
environment. The charger height and depth are the same as the Power
Products’ discharge tester, Beta D-50, with the same general appearance.
Therefore, two adjacent units comprise a charger/discharger, which can
service from one to three batteries simultaneously, lead-acid or nickel
cadmium.

The Alpha C-25 allows charging at both constant potential and constant
current to give flexibility in selection of charge method. The C-25 charger
has an adjustable charge current from 0 to 25 amperes in the CP mode.
End of voltage settings should be 14.3 for 12 Volt and 28.5 for 24 Volt
batteries. Panel trimpots allow user voltage changes if required. In CC
mode, there is no voltage adjustment. Maximum voltage is approximately
37 volts. Two digital panel meters allow viewing of charge current and
voltage. They can be switched to allow viewing of either of the two batteries
being charged. A digital electronic timer displays elapsed time and can be
set to a fixed duration charge period.

The flexibility of settings of the Alpha C-25 makes it usable for a wide variety
of batteries and voltages. The unit efficiently charges Lead Acid batteries of
12 or 24 volts, as well as Nickel Cadmium batteries of a single cell to 24
volts.

1.2 DISPLAYS AND CONTROLS

The Alpha C-25 has been designed to have very simple and easy to
understand controls and displays (see figure 1-1 and 1-2).

NOTE: A trimpot for the 12 Volt, and a trimpot for the 24 Volt constant
potential setting has been added for adjustment of the end of charge
voltage.

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1. SYSTEM OVERVIEW

DIGITAL CHARGE TIMER

Displays elapsed charge time.
Can be set to fixed duration
charge times

DIGITAL
VOLTMETER

Displays battery
voltage during
charge

CHARGE MODE
SELECT KNOB

Selects constant current
or constant potential
mode for 12 or 24 volt
batteries

DIGITAL AMMETER

Displays charge
current

INSTRUCTION
PANEL

AMPERE
ADJUST KNOB

Sets current
charge

ON/OFF LAMPS

Illuminate to indicate if
unit is charging (on) or
not (off)

BATTERY VIEW
SWITCH

Switches between
displaying current
and voltage for
battery one or
battery two

AC ON/OFF
SWITCH

Turns unit on
or off

DC LINE FUSE

Fuse protecting
DC line

START
BUTTON

Pressed to
start charge

DC LINE CONNECTORS

Connects for DC cable
leading to battery

ALPHA C-20/25 CHARGER – OPERATING MANUAL V1.0 Page 4

Figure 1–1. Front view of Alpha C-25

1. SYSTEM OVERVIEW

AC LINE FUSE

AC VOLTAGE
SELECT SWITCH

Selects mains input
voltage (120 or 230
volts)

COOLING FANS

AC MAINS CABLE

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Figure 1–2. Rear view of Alpha C-25

2. INSTALLATION

2. INSTALLATION

2.1 LINE VOLTAGE

The Alpha C-25 can operate on either 120 or 230 Volts AC. The desired line
voltage can be selected on the rear of the unit.

CAUTION: Ensure that the unit is set for the appropriate

line voltage before operation.
A. On the back of the unit locate the AC voltage select switch.
B. Set switch for appropriately marked AC voltage (120 or 230 volts).
C. For 230 VAC operation, the 120 VAC plug must be replaced with one

for 230 VAC in required configuration.

NOTE: If the plug has to be changed make sure to connect

the green AC line wire to ground.
Connect the unit to a wall outlet with a 15-20 ampere capacity. Sharing of

the line with other equipment may result in erratic operation if other
equipment draws high pulse or surge currents.

NOTE: The Alpha C-25 will maintain its operational

integrity with line fluctuation less than ± 5%.

2.2 TERMINALS

The Alpha C-25 is supplied with two DC cables. One cable has an aircraft
battery quick-disconnect connector and one has ring terminals. If the quick­disconnect connector is removed, the ring terminals can be used to connect
to a post terminal battery, or be fitted to a different quick-disconnect
connector.

WARNING: Correct polarity must be observed.

2.3 SPACE REQUIREMENTS

The Alpha C-25 system occupies 15" x 5 ¾" (381 mm x 146 mm) of tabletop
space. Place the unit on a sturdy workbench in a well-ventilated battery
servicing area with the battery adjacent to it.

ALPHA C-20/25 CHARGER – OPERATING MANUAL V1.0 Page 6

2. INSTALLATION

The rear of the unit has air flow for cooling. Allow at least 6" (150 mm) of
separation from the wall and adjacent equipment in order to maintain proper
air flow.

NOTE: In non air-conditioned rooms it is recommended

that circulating or extracting fans be used to aid in the

removal of heated air.

NOTE: Operation in dusty or otherwise dirty air

environments will severely reduce the cooling capacity of

the fans and can lead to premature failure.

3. OPERATING GUIDE

This section gives an overview of how to charge a battery using the Alpha C-25. Always

refer to the battery manufacturers’ maintenance manual for their recommended

charging methods and settings.

3.1 CHARGE CHARACTERISTICS

The constant current charge characteristics of a lead-acid cell with respect to cell
voltage, ampere-hours input, specific gravity and rate of gassing at constant
current can be seen in figure 3-1.

Figure 3-1. Charge characteristics of a lead-acid cell

ALPHA C-20/25 CHARGER – OPERATING MANUAL V1.0 Page 7

3. OPERATING GUIDE

As shown by the curve in figure 3-1 the cell voltage of a discharged battery rises
rapidly when the battery is first placed on charge. The extent of the initial rise
depends on the charging rate. As the charge continues, the voltage rises at a
slower rate and eventually levels off when a full state-of-charge is reached. It can
be seen that the specific gravity reading lags behind the rate of ampere-hour return
during most of the charging cycle. Consequently, the specific gravity is not
indicative of the available ampere-hour capacity until the cell approaches a full­charge state.
When a battery reaches a full state-of-charge the voltage of the battery will
stabilize and remain constant or decrease (in constant current mode). The
charging should discontinue at this stage. A minimum of 103% of previous
discharge should be placed in the battery.

In general a vented battery may be charged at any rate that will not produce
excessive gassing or electrolyte temperatures above 113°F (45°C). VRLA
batteries should never be charged in a constant-current mode with a current
greater than C1/10 (C1 equals the rated capacity of the battery). During constant
current charging at a rate in excess of C1/10, oxygen is produced at an excessive
rate. The resulting increasing pressure will cause the cell to vent. Venting of
gasses results in a depletion of electrolyte. As the electrolyte cannot be replaced in
a sealed battery, the cell will dry out resulting in a decrease in capacity and
eventually battery failure. Therefore constant-potential charging is the
recommended charge method for valve regulated lead acid batteries

3.2 CHARGING METHODS

There are two main methods of charging a battery:

1) Constant current

2) Constant potential.
In what follows both methods will be described in some detail.

3.2.1 CONSTANT-CURRENT CHARGE METHOD

In this method the current remains at a preset level while the voltage can reach a
high level, e.g. 34-37 volts.

An advantage of the constant-current charge method is that the ampere-hour input
into the battery can be determined precisely by multiplying the charging current
with the charge time in hours. However, it is necessary to ensure that the battery is
not charged at a high rate for an excessive period of time. Such overcharging can
result in overheating, excessive gassing, and possible damage to the battery.

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