NORMILIZATION AND CONDITIONING OF NICKEL METAL HYDRRIDE BATTERIES

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NORMILIZATION AND CONDITIONING OF NICKEL METAL
HYDRRIDE BATTERIES

• By Chris Harrison

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INTRODUCTION
Charging is the way to restore energy back into
batteries that are empty. Rechargeable
batteries are important because they can be
reused. Batteries can be charged in many ways
to produce certain results. - Charge 1 fast
charges batteries for electric vehicles
applications.- Charge 2 recovers batteries that
have been unused for an extended period of time.
Charges affect many important battery
aspects- Battery Life - Battery Capacity -
Battery Performance
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BATTERY EFFECTS Internal Battery Resistance -
As the battery gets increasingly full, it
becomes harder to squeeze in the remaining
energy. Self Discharge - Batteries naturally
decrease in energy as chemicals slowly react
inside the battery. SIMPLE CHARGE TYPES
Constant Current- Charges at a certain current
for a specified time.- As internal battery
resistance increases and current does not drop,
temperature can increase. This may damage the
battery and be a safety hazard. Trickle
Charge- Same as constant current, but uses very
low currents. - Low current allow full
batteries resist further charging while empty
batteries catch up.
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Trickle charge movie
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CHARGE TERMINATION TYPES
Time Voltage Temperature and ?Temperature
?Voltage
FACTORS EFFECTED BY CHARGING
Charging Efficiency Charging time Battery
Life Battery Capacity Battery Performance
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EXAMPLES
EXAMPLE PROFILE 1 Begins charge with a high
initial current and then drops to a lower
current. POSSIBLE RESULT May produce good
charge time, but reduces battery
performance. EXAMPLE PROFILE 1 Begins charging
with a low current then rises to a high
current. POSSIBLE RESULT May have poor charge
efficiency and damages battery because of extreme
heat and reduces battery capacity.
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REVIEW OF THE LITERATURE
Maintenance-Free Batteries, 2nd Edition, D.
Berndt, Research Studies Press Ltd., Somerset,
1997. The Fifteenth Annual Battery Conference
on Applications and Advances (Proceedings),
California State University, Long Beach, Jan
11-14, 2000. Improved Charge Algorithms for
Valve Regulated Lead-Acid Batteries, E Sexton Et
Al. Page 211. John Rivera (Technician) and Jon
Marshall (Engineering Group Leader), Curtis
Instruments, Inc. Mount Kisco, NY.
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METHODS
1 - Determine how many Amp Hours to charge or
discharge from the battery / battery pack 2
- Calculate time and current for charge 3 -
Determine what charge would be best to
normalize batteries 4 - Determine termination
type 4 - Insert batteries into holder 5 - Set up
apparatus for desired parameters 6 - Start
monitoring charge statistics (e.g. current,
voltage) 7 - Start charge 8 - Analyze end float
voltages, and prepare for next charge or
discharge based of collected data
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FUTURE RESEARCH
CHARGING CURRENT VS. TEMPERATURE Intense
Charging - More current flows through wires
and battery - Generates lots of heat -
Could damage the fragile internal
materials PRESENT TECHNOLOGY Terminates when
- Threshold temperature is reached -
Temperature change reaches a certain slope,
This allows the battery to cool Resumes the
charge until it reaches that temperature again.
These pauses waste time. Stop-and-go
charging could damage the battery. FUTURE
RESEARCH - Temperature regulated charge algorithms
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