Battery Charger
Model GSK-819
This kit contains parts to assemble a Lithium-ion Polymer
battery charger. These batteries are becoming popular with
radio controlled devices, iPods
®
, MP3, and laptop computers.
Technical Specifications
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Power Source: 12-15 VDC, more than 600 mA
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Charge Current: 400 mA or 600 mA (selectable)
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Charge: 1 to 2 cells
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Charge Indicator: LED
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Cut Off: Automatic cut-off circuit when battery fully charged
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Power source polarity protected
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PCB Dimensions: 3.73 x 2.44 inches
Operating Principles
When power source is applied IC2 will regulate the voltage to a
suitable amount for charging. Integrated circuits control the output
voltage, switch SW1 controls selectable charge current (H = 600
mA and L = 400 mA), and switch SW2 controls the number of
cells (1 cell 3.7 V) an (2 cells 7.4 V). When battery is fully charged
IC1 applies voltage to IC2 and initiates cut-off circuit. LED’s are on
when battery is charging and off when battery is fully charged.
Circuit Assembly
Please refer to Figures 1, 2, and 3 for aid in component
placement. It is recommended to start with lower components
i.e. diodes, resisters, electrolyte capacitors, and transistors.
Be careful to check polarity with Figure 2 before soldering.
Take extra precaution to ensure electrolytic capacitors are
inserted correctly. If a problem is detected it is best too use a
desoldering pump or desoldering braids to remove component.
This will minimize potential damage to the printed circuit board.
Testing
Connect the power source, LED LSW and LED L5V should
light. Measure voltage at TP point and adjust voltage to 4.2 V
using VR1K. Select charging current using SW1 (H = 600 mA,
L = 400 mA), select number of cells in battery using SW2
(position 1 = 1 cell, position 2 = 2 cells).
Connect Li-Po battery to charger at position “OUT,” LED
“Charge” will light to indicate battery is charging. When
battery is fully charged LED “LSW” and LED “Charge” will
be off. Disconnect battery from charger and wait for the LED
“LSW” to turn on before trying to charge another battery.
Charger will not charge until the LED “LSW” is on.
Troubleshooting
This circuit has only a few components. The main cause of
problems will come from misplaced components or faulty
soldering. Utilize Figure 2 to ensure proper placement/polarity
and then check solder points for connectivity.
Accessories
Use GSB-04 (sold separately) to house the PCB and batteries.
iPod
®
is a registered trademark of Apple Inc.
Electronic Kit Set for Hobby & Education
Figure 1
Lithium-ion Polymar Charger Circuit
