Power Products ALPHA C-20 User manual

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
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
CLASSESOF 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
ALPHA C-20/25 CHARGER –OPERATING MANUAL V1.0 Page 3
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.

1. SYSTEM OVERVIEW
ALPHA C-20/25 CHARGER –OPERATING MANUAL V1.0 Page 4
Figure 1–1. Front view of Alpha C-25
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

1. SYSTEM OVERVIEW
ALPHA C-20/25 CHARGER –OPERATING MANUAL V1.0 Page 5
Figure 1–2. Rear view of Alpha C-25
AC LINE FUSE
AC VOLTAGE
SELECT SWITCH
Selects mains input
voltage (120 or 230
volts)
COOLING FANS
AC MAINS CABLE

2. INSTALLATION
ALPHA C-20/25 CHARGER –OPERATING MANUAL V1.0 Page 6
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 quick-
disconnect 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.

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

3. OPERATING GUIDE
ALPHA C-20/25 CHARGER –OPERATING MANUAL V1.0 Page 8
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 full-
charge 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 (C1equals 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.

3. OPERATING GUIDE
ALPHA C-20/25 CHARGER –OPERATING MANUAL V1.0 Page 9
3.2.2 CONSTANT-POTENTIAL CHARGE METHOD
A charge source applies a fixed (constant) voltage (potential) to the battery. The
current supplied by the charge source fluctuates (rises and falls) with the battery
voltage.
There are several advantages of the constant-potential charge method. First, there
is less danger of gassing at an excessive rate. Secondly, batteries of the same
nominal voltage but with different capacities can be connected in parallel directly to
the charging source. Thirdly, batteries are charged more rapidly and with less
attention.
3.2.3 LEAD-ACID BATTERIES
With the constant-current charge method the voltage can climb to 34-37 volts.
Therefore, this method should normally not be used to charge lead-acid batteries,
especially not the sealed type VRLA (valve regulated lead acid). A preferred way is
to have the VRLA batteries constant-potential charged on automatic equipment at
a voltage of 28.5 +/ –0.25 volts until the charge current stabilizes for 3 consecutive
hourly readings.
The constant-current charge method can however be used for reconditioning
VRLA’s. For conditioning VRLA batteries, first discharge 12 volt batteries to 9 volts
or 18 volts for 24 volt batteries, then recharge with CC (constant current) at the
C1/10 rate (one tenth of the C1rate or one hour capacity) for 16 hours. The battery
should be periodically monitored for overheating during reconditioning.
3.2.4 NICKEL-CADMIUM BATTERIES
Nickel-cadmium batteries may be initially charged with constant potential set to
14.3 (12 volt battery) or 28.5 (24 volt battery). After the initial charge the batteries
could be topped with a low constant-current (usually C1/10) charge.
The nickel-cadmium can also be completely charged in the constant-current mode.
Adjust the current to a lower rate for topping. A low constant current applied during
a long time can also be used to eliminate fading, previously called the “memory
effect”, from nickel-cadmium batteries.
3.3 PREPARATION FOR CHARGING
Before starting charging the battery, read the component maintenance manual
(CMM) or the Instructions for Continued Airworthiness (ICA) for the specific
battery. Ensure that the charge time and current or voltages from the battery
manufacturer are followed.

3. OPERATING GUIDE
ALPHA C-20/25 CHARGER –OPERATING MANUAL V1.0 Page 10
It is recommended that a visual inspection of the battery is carried out in
conjunction with testing and charging batteries. The charging, unless otherwise
specified in the manufacturer's CMM/ ICA, shall be conducted at room ambient
temperature of 70°F to 85°F (21°C to 29°C).
3.3.1 VERIFY THE CP VOLTAGE
The CP voltage (in all modes) can be verified by the following steps: 1) turn unit
power off; 2) disconnect all batteries; 3) turn charge current to max; 4) turn unit
power on; and 5) verify the CP voltage on the Alpha C-25 digital voltmeter (see
also section 4.5 on modifying the operating range).
WARNING: Always turn the AC power switch off before
connecting or disconnecting a battery
NOTE: Once set, all settings are maintained and need not
be reset for duplicate charging
A. SWITCH OFF MAINS POWER
Turn off the AC on-off/reset power switch.
B. TURN DOWN CHARGE CURRENT
Repeatedly turn the Ampere Adjust knob fully
counter-clockwise to set charge current to
zero.

3. OPERATING GUIDE
ALPHA C-20/25 CHARGER –OPERATING MANUAL V1.0 Page 11
3.4 CHARGE TIME
3.4.1 TIMER UNIT SETTING
The Alpha C-25 has a built in timer, allowing charge time settings from 1 to 999
minutes.
3.4.2 CHARGE TIME SETTING
The charge time will be set based on the state of charge of the battery and at
which rate the battery is being charged.
Refer to your battery manufacturer's CMM (Component Maintenance Manual) or
ICA (Instructions for Continued Airworthiness) for the most accurate information.
C. SET TIMER
Set the timer by adjusting the thumb-dial to
the required charge time.
D. SELECT CHARGE MODE
Turn the Charge Mode Select knob to the
desired mode: 1) Constant potential 14.3
volts; 2) Constant current; or 3) Constant
potential 28.5 volts. If two batteries are to be
charged simultaneously, they will both be
charged using the selected charge mode.

3. OPERATING GUIDE
ALPHA C-20/25 CHARGER –OPERATING MANUAL V1.0 Page 12
E. CONNECT ONE OR TWO
BATTERIES
Connect the battery DC cable(s) to the Alpha
C25 DC Line Connectors on the front of the
unit. For single battery always use
“BATTERY 1” output. Connect the other end
of the cable(s) to the battery (or batteries).
Ensure the connectors are plugged in
completely.
F. SET BATTERY VIEW
Set the battery view switch to “VIEW BATT. 1”
G.SWITCH ON MAINS POWER
Turn on the AC on/off power switch. The
voltmeter reads the battery terminal voltage,
the ammeter reads zero, the Off lamp
illuminates and the red LED on the timer is
off.

3. OPERATING GUIDE
ALPHA C-20/25 CHARGER –OPERATING MANUAL V1.0 Page 13
H. PUSH START BUTTON
The timer starts. The On lamp and the red
LED on the timer illuminate. The voltmeter
displays the battery terminal voltage and the
ammeter reads zero.
I. SET CHARGE CURRENT
1. FOR CONSTANT-CURRENT
CHARGING
Turn the Ampere Adjust knob until the
desired charge current has been reached.
The charge current is displayed on the
ammeter as the current is being adjusted.
2. FOR CONSTANT-POTENTIAL
CHARGING
Turn the Ampere Adjust knob to max (fully
clockwise) or to the desired current limit. The
charge current is displayed on the ammeter
as the current is being adjusted.

3. OPERATING GUIDE
ALPHA C-20/25 CHARGER –OPERATING MANUAL V1.0 Page 14
J. WAIT FOR THE CHARGE TO AUTOMATICALLY
COMPLETE
During the charging of the battery the battery voltage, charge current, and
elapsed charge time are displayed.
For the constant-current method the current remains constant while
the voltage increases during the time of charging.
For the constant-potential method the charger’s end voltage remains
constant while the current starts at a high value and gradually
approaches zero as the battery approaches a full charge.
The actual charge current is determined by the battery, until the constant
voltage is reached (14.3 volts for 12 volt batteries and 28.5 volts for 24 volt
batteries).
The charging time ends when the current remains constant (within 10%) for
3 consecutive hourly readings or the set charge time has been reached.
The Off lamp illuminates.
K. UPDATE BATTERY RECORDS
Record the charge data in the battery records to ensure good maintenance
of the battery.
L. SWITCH AC POWER OFF
Switch the AC on/off switch off before
removing the battery.
NOTE: If in emergency it is required to stop
charging, switch the unit to off. When
charging is restarted the timer is reset to
zero. It may be necessary to adjust the
parameters (current and time) before
resuming to charge.

4. CALIBRATION AND MAINTENANCE
ALPHA C-20/25 CHARGER –OPERATING MANUAL V1.0 Page 15
4. CALIBRATION AND MAINTENANCE
4.1 OVERVIEW OF CALIBRATION
The Alpha C-25 has been calibrated before shipment from the manufacturer. A
certificate of calibration with test instruments traceable to the National Institute of
Standards and Testing in accordance with MIL-I-45208A has been issued and is
enclosed in the back of this manual. To ensure error-free operation over time,
calibration should be verified every 12 months depending on usage and changes in
surrounding environment.
4.1.1 DIGITAL PANEL METERS
There are two main indicators that can be periodically verified: 1) the voltmeter;
and 2) the ammeter (see figure 1-1 in section 1). In addition the internal shunt,
even though calibrated and certified by the shunt manufacturer, could be verified.
4.1.2 TIMER
The timer is a very accurate crystal-controlled device, not prone to error. It cannot
be re-calibrated, but unless an extremely accurate time reading is required, an
accurate analog or digital stop watch is adequate to validate its accuracy.
4.1.3 OPERATING RANGES
The Alpha C-25 gives the capabilities with panel mounted trimpot to modify the
charge voltage in constant-potential mode. There is no adjust for voltage limit in
constant current.
The Alpha C-25 Battery Charger now includes external test point jacks
for voltage and current verification.
Voltage Verification –Do not connect C-25 to battery. Select 28.5 V
setting. Using an external calibrated digital meter (set to DC Volt
scale), connect to voltmeter test jacks and verify voltage panel meter
is within approximately 0.3 volts.
Current Verification - Connect C-25 to a discharged battery
and charge at approx. 20 Amps. Using an external calibrated
digital meter (set to millivolt scale), connect to ammeter test
jacks and verify panel meter is within approx. 0.3 Amps.

4. CALIBRATION AND MAINTENANCE
ALPHA C-20/25 CHARGER –OPERATING MANUAL V1.0 Page 16
4.2 SHUNT VERIFICATION
The Alpha C-25 internal shunt is calibrated and certified by the shunt
manufacturer. The shunt is a linear resistive device consisting of a heavy brass
base and heavy manganin (copper alloy) resistance. It is not necessary to calibrate
the shunt, however the shunt could be verified with the help of an external
calibrated shunt and a millivoltmeter (see figure 4-3).
EXTERNAL CALIBRATED
MILLIVOLTMETER
Figure 4-3 Circuit diagram for shunt verification
4.3 OPERATING RANGES
The main Alpha C-25 circuit board P/N BD50PC had factory-preset trimpots for
modifying voltages settings and limits. Those trimpots are now accessible from the
front panel.
4.3.1 MODIFYING VOLTAGES FOR CONSTANT-POTENTIAL MODE
Select 12 or 24 Volt as required. Without battery connected, check end voltages of
14.3 or 28.5 volts. Trim if necessary or if different voltages are required.
4.3.2 MODIFYING MAXIMUM VOLTAGE SETTING
To modify the maximum voltage limit in constant-current mode adjust the R11
trimpot on PCB BD50PC.

4. CALIBRATION AND MAINTENANCE
ALPHA C-20/25 CHARGER –OPERATING MANUAL V1.0 Page 17
4.4 MAINTENANCE
Standard electrical equipment maintenance and cleaning procedures should be
followed.
4.4.1 VENTS AND FAN
Regularly check that the rear fan vents are clean to ensure adequate cooling of the
unit. This is especially important when the unit is placed in a dusty or otherwise
dirty air environment.
4.4.2 DC BATTERY CABLES
Inspect DC battery cables and connectors periodically. Replace damaged or worn
cable.
4.4.3 REPLACEMENT OF FUSES
The Alpha C-25 is equipped with three fuses. One 20 ampere AC line fuse and two
35 ampere DC line fuses. See specification in section 6 for the specific types of
fuses required.
WARNING: Disconnect AC voltage and battery before
attempting to replace any fuses.
To replace the AC line fuse unscrew the fuse cover on the rear of the unit and
exchange the old fuse (see picture 1-2 in section 1).
To replace the DC line fuses unscrew the fuse cover just above the DC Line
Connector and exchange the old fuse (see picture 1-1 in section 1).
4.4.4 CLEANING AGENTS
Do not use acetone and other similar cleaning agents on the meters, timer or any
plastic part.

6. SPECIFICATIONS
ALPHA C-20/25 CHARGER –OPERATING MANUAL V1.0 Page 18
5. TROUBLESHOOTING
Problem Possible Cause Corrective Action
A. Unit will not
turn on
The AC power is not
connected to unit
Check AC line with voltmeter
AC line fuse is blown. May be
due to incorrect AC line
voltage setting.
Ensure correct AC line voltage
setting on back of unit. (see section
2.1)
Replace AC line fuse located on the
lower right hand side on the rear of
the unit (see section 4.6)
B. Unit turns on
but will not start
(timing)
Timer is set to zero time,
Increase the timer setting (see
section 3.4)
C. No or very low
charge current
The lead-acid battery is
sulfated and will not support a
load
Recondition or discard the battery
High resistance or open
circuit in DC cable at quick
disconnect, in the cable itself
Inspect and measure resistance in
DC cable and connector. If high or
intermittent high resistance, the
cable needs to be replaced
The lead-acid battery is
sulfated.
Recondition the battery.
The nickel-cadmium battery
inter-cell connectors are loose
or contaminated causing high
resistance
Check all terminals and inter-cell
connectors. Set a low discharge
current and look for arcing or heat
generation.

6. SPECIFICATIONS
ALPHA C-20/25 CHARGER –OPERATING MANUAL V1.0 Page 19
6. SPECIFICATIONS
AC Line Input:
120 volts ± 5%, 50/60Hz, 13 amperes or
230 volts ± 5%, 50/60Hz, 6 amperes
(selectable on rear of unit) NOTE: Unit will
operate ± 10% but with lower max amp
ratings at -10%.
Constant Current
Mode:
Capacity
Accuracy
Approx. 37 volt limit non-adjustable. 0-7 to 8
amps at 37 volts.
< ± 3% from charge initiation to completion
Constant Potential
Mode
Setting
Selectable 14.3/28.5 volts; 25 ampere limit
Accuracy
< ± 0.2 volts
Timer
Setting
Adjustable from 0 to 999 minutes
Units
Selectable on front of timer from 1 to 999
minutes
Accuracy
< ± 0.1%
Digital
Meter Accuracy:
Voltmeter
< ± 0.3 volts
Ammeter
< ± 0.3 amperes
Cooling:
Fan cooled
Housing:
Aluminum chassis
Outer Dimensions:
Height
14 in. (356 mm)
Depth
15 in. (381 mm)
Width
5 3/4 in. (146 mm)
AC Line Cord:
AWG 14 3 wire grounded 6 ft long with 120
volt 15 ampere plug. User required to change
to 230 volt plug.
DC Discharge
Cable:
Two 4 ft long, terminated in ring terminals
(Aircraft Battery Connector Optional)
Weight:
Net 40 lbs. (18.2 kg) Shipping 48 lbs.
Fuses:
AC line fuse
20A/250V, type MDA 1 1/4 x 1/4
DC line fuses
Two 35A/32V, type AGC 1 1/4 x 1/4
Modes:
1) Constant Current mode without voltage
limit
2) Constant Potential mode for 12 volt and
24 volt batteries.

APPENDIX A –BATTERY OVERVIEW
ALPHA C-20/25 CHARGER –OPERATING MANUAL V1.0 Page 20
APPENDIX
APPENDIX A - BATTERY OVERVIEW
CLASSES OF BATTERIES
Batteries can be divided into two major classes: primary and secondary. The primary
batteries are not practically reusable once its useful energy has been discharged. The
secondary battery is rechargeable. In the following only secondary batteries will be
covered.
SECONDARY BATTERIES
Secondary batteries differ from primary batteries in that they may be recharged. Some
of the materials in the cells of primary batteries are usually consumed in the process of
changing chemical energy into electrical energy. In the secondary system, the materials
are transferred from one electrode to the other as the cells discharge. The cells are
restored to their original state of charge by forcing an electric current through the cells in
a direction opposite to that of the discharge. These batteries are used in a multitude of
applications ranging from megawatt sizes in submarines to milliwatt sizes in portable
radios.
LEAD-ACID BATTERIES, VENTED OR VRLA
The lead-acid battery is a rechargeable system using acid electrolyte
(sulfuric acid and water). Lead-acid batteries may be vented or sealed.
The advantages of lead-acid batteries are that they have a low initial
cost, require low maintenance, and their discard cost is low. The VRLA
batteries, on a per-weight basis, provides as much power as a nickel-
cadmium battery. Vented Lead-acid batteries shed active material from
the positive plate, proportional to the number of charge/discharge
cycles. For Vented lead-acid batteries this results in diminishing battery
performance with age and loss of active material on the positive plates
due to the washing action of the gas bubbles generated during charge.
The open circuit voltage of a fully charged cell is about 2.15-2.20 volts.
The discharge voltage is about 2.0 volts and varies with temperature,
discharge rate, charge state, and age. The VRLA batteries are
normally charged in the CP mode.
The lead-acid battery is the most widely used of the secondary battery types. Major
applications include automobiles, aircraft, aircraft support equipment, and various
industrial applications.