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Fast charging of Lead acid
batteries with pulse charger
Dr. S. N. Joshi,
Lalit Consulting Services,
Bangalore. INDIA
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Lead acid battery application logic
Lead acid battery is a power source.
Need to put back energy once it is used.
Battery recharge becomes veryimportant.
Discharge followed by recharge is cycle.
Depending upon depth of dischargerecharge current & or voltage is decided
by the charger.
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Fast charging of Lead acid battery
Lead acid batteries are very essential in
our daily life.
Many applications like SLI, UPS,
telecom etc. are well known.
Fast charging of batteries in case of
battery operated vehicles has
significance to the user.
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Fast charging of Lead acid battery
Chargers used for battery operated
vehicles have basic features:
1.To convert AC to DC through rectifier
bridge.
2.Logic control & monitoring the charge
input.
3.Safety protection & display or record
events of the system.
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Charging system for Lead acid battery
Selection of charger is very critical. Itdepends on:
1.Design of the system & nature of its load
requirement.2.Desired recharge time after every load
cycle.
3.Effect on battery life & maintenanceaspects.
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Charging of Lead acid battery
Examples of recharging systems are:
1.SLI - Alternator charger
2.UPS - Float charging3.Power plants / telecom applications -
Float-cum-boost charger.
4.Fork lift / EVs / Golf cart - Taper / twostep / fast charging.
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Chemical equation in battery reaction
Consider electrochemical reactions in
Lead acid battery producing electron
transfer & voltage across electrodes,
-DC
PbO2 + 2 H2SO4 + Pb 2PbSO4 + 2 H2O
+DC
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Lead acid battery side reactions
There are however side reactions:
1. Generation of gases like oxygen &
hydrogen.
2. Loss of water.
3. Effect on life of battery.
4. Maintenance issue plays part.5. Charger, its design & method of
charging becomes crucial.
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Fast charging of Lead acid battery
Fast charging in case of battery operated
vehicles is desired by users:
1. Fork lifts.2. Pallet trucks.
3. Cars, buses.
4. Scoter, bikes.
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Fast charging of Lead acid battery
Battery operated vehicle should get
recharged quickly after specific task.
1. Desired work is done the vehicle.
2. Waiting time is minimum.
3. Utilization of vehicle is improved.
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Fast charging of Lead acid battery
Fast charging means:
1. Reduction from normal recharge time.
2. At least 80% energy should be putback.
3. Battery plates should not be damaged.
4. Minimize side reactionsloss of water.
5. Reduce maintenance aspects.
6. Covert lead sulphate back into activemass !!!
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Fast charging of Lead acid battery
Charger design:
Uses higher voltage for shorter timeintervals of seconds or mille-seconds.
DC current in PULSE form is appliedfor short durations of seconds or mille-seconds. Switched off for m-seconds.
Both voltage & pulse current are micro-processor controller with programmedembedded software.
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Fast charging of Lead acid battery
Pulse charging:
1.The technique restores energy in quickest wayback into lead acid battery.
2.Pulse height & width are selected in such away that entire energy is accepted with leastloss.
3.Current in pulsating form is generated by
complex & intelligent electronic circuit coupledwith embedded software.
4.Temperature sensor employed to restrictenergy losses & undesired side reactions.
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Laboratory testing
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Fast charging of Lead acid battery
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Bench test with DC motor
Table 1. Bench test results of recharge.
Bench test - DC Motor (250 W) testing system.
Duration 2 Hrs : 55 minutes, average current 5.5 A, End voltage 44.3 V
B1 V B2 V B3 V B4 V Total V
OCV 11.95 11.86 11.85 11.92 47.5
6 hours 13.57 13.52 13.57 13.51 54.10
8 hours 14.69 14.67 14.65 14.66 58.67
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Road test on e-bike
Charge coverage test on road:
Covered 62 kms of distance.
B1 V B2 V B3 V B4 V Total V
OCV 11.63 11.45 11.68 11.47 46.23
6 hrs. 13.58 13.52 13.51 13.57 54.18
8 hrs. 14.32 14.35 14.33 14.37 57.37
Second road test covered distance of 60 kms.
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EBike charging
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Pulse charging of Lead acid battery
Application to battery operated vehicles
is very appropriate to bring in high
utilization of vehicles in shot time.
Electric vehicle (passenger) like cycle,
bike or car demands such type of fast
recharge of battery for the user.
Fork lifts / pallet trucks in industrial
application also need such charger.
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Pulse charging of Lead acid battery
Pulse charger however calls for high end
complicated electronic circuit in combination with
1.battery chemistry,
2.impedance values of lead acid cell at various
SOC.
3.effect of temperature on charge acceptance.
4.correlation with battery voltages & pulseamplitude and time.
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PULSE CHARGER: MAIN FEATURES
Desulfates & charges at the same time.
Automatically shuts off when battery isfully charged.
Helps ensure battery performance byeliminating the main cause of lead-acidbattery failuresulfation buildup &
related problems. Maximum Output: 110 volts DC, up to 35
amps DC.
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PULSE CHARGER: MAIN FEATURES
Helps protect the environment.
Works with all conventional flooded lead-
acid batteries and sealed "maintenance-
free" batteries (VRLA).
Reverse polarity protection.
Over voltage protected. Short circuit protection.
Overload protection.
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Pulse charger 48 V 3 A
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Acknowledgement
Pulse charger is commercially build & supplied:
By M/s CHIRRA POWER TECHNOLOGIES,
Bangalore with technical assistance fromLalit Consulting Services, Bangalore. INDIA
E-mail: [email protected]
Thank you all
mailto:[email protected]:[email protected]:[email protected]:[email protected]