1. German Jordanian University
School of Applied Technical Sciences
Mechanical and Maintenance Engineering Department
TME592 – Graduation Project
Evaluation and Repurposing of Post-Automotive-Application Batteries
Prepared By
Abdulaziz Kadri ID 2011105023
Ali Ruziyeh ID 2011105015
Supervised By
Dr. Ahmad Al-Muhtady
Dr. Hani Muhsen
Submitted as Partial Fulfillment of the Requirements for the Bachelor's Degree of Science
in Mechanical and Maintenance Engineering 1st
semester, 2016/2017
2. i
CONTENTS
LIST OF FIGURES ......................................................................................................................................................ii
LIST OF TABLES.......................................................................................................................................................iii
Nomenclature............................................................................................................................................................... iv
Subscripts...................................................................................................................................................................... v
Abstract........................................................................................................................................................................vi
Acknowledgment ........................................................................................................................................................vii
Chapter 1....................................................................................................................................................................... 1
Problem Statement.................................................................................................................................................... 2
Objectives ................................................................................................................................................................. 2
General objectives ................................................................................................................................................ 2
Detailed objectives ............................................................................................................................................... 2
Chapter 2....................................................................................................................................................................... 4
Background of the project......................................................................................................................................... 5
Literature Review ..................................................................................................................................................... 9
Chapter 3..................................................................................................................................................................... 18
Battery Testing ....................................................................................................................................................... 19
Arduino Sensors ................................................................................................................................................. 20
Charging the battery ........................................................................................................................................... 24
Discharging the battery ...................................................................................................................................... 26
Test Monitoring & data analyzing...................................................................................................................... 28
Chapter 4..................................................................................................................................................................... 30
Charging Results..................................................................................................................................................... 32
Discharging Results................................................................................................................................................ 36
Batteries Categorization.......................................................................................................................................... 41
Chapter 5..................................................................................................................................................................... 42
Solar Power............................................................................................................................................................. 44
1. House application UPS.............................................................................................................................. 45
2. Army Towers Application ......................................................................................................................... 48
Mechanical power................................................................................................................................................... 50
Degradation ............................................................................................................................................................ 51
Chapter 6..................................................................................................................................................................... 53
Project Summary .................................................................................................................................................... 54
Recommendations AND Future Work.................................................................................................................... 55
References................................................................................................................................................................... 56
3. ii
LIST OF FIGURES
FIGURE 1: GJU PRESIDENT PLUG-IN ELECTRIC VEHICLE................................................................................................. 7
FIGURE 2: INFLUENCE OF TEMPERATURE ON CYCLE LIFE [5]........................................................................................ 12
FIGURE 3: FIGURE 3 EXAMPLE OF THE DEPENDENCE OF THE CYCLE LIFE ON THE DOD [5].......................................... 13
FIGURE 4: AGING DATA FROM THE PRIUS BATTERY PACK [5]..................................................................................... 14
FIGURE 5: DISCHARGING CYCLE WITH INTERNAL RESISTANCE [11]............................................................................. 15
FIGURE 6: TWENTY SIX DIFFERENT LITHIUM-ION BATTERY CAPACITY DEGRADATION DATA [15]................................ 17
FIGURE 7: PRELIMINARY TESTING CIRCUIT OF THE USED BATTERY............................................................................ 20
FIGURE 8: VOLTAGE DIVIDER...................................................................................................................................... 21
FIGURE 9: PRELIMINARY HYBRID BATTERY TESTING SCHEME..................................................................................... 22
FIGURE 10: IMAX B6 CHARGER & DISCHARGER........................................................................................................ 23
FIGURE 11: CURRENT SENSOR...................................................................................................................................... 23
FIGURE 12: VOLTAGE DIVIDER.................................................................................................................................... 24
FIGURE 13: INFRARED TEMPERATURE SENSOR............................................................................................................ 24
FIGURE 14: ONE-LAMP RESISTOR DISCHARGING .......................................................................................................... 27
FIGURE 15: THREE-LAMPS RESISTORS DISCHARGING.................................................................................................... 27
FIGURE 16: SAFETY BOX ............................................................................................................................................. 29
FIGURE 17: RELATIVE ENERGY CAPACITY HISTOGRAM .............................................................................................. 32
FIGURE 18: CHARGING VOLTAGE VS. TIME ................................................................................................................. 33
FIGURE 19: CHARGING CURRENT VS. TIME.................................................................................................................. 34
FIGURE 20: ENERGY CHARGED TO THE BATTERIES ...................................................................................................... 35
FIGURE 21: DISCHARGING VOLTAGE VS. TIME ............................................................................................................ 36
FIGURE 22: DISCHARGING CURRENT VS. TIME ............................................................................................................ 37
FIGURE 23: DISCHARGING CURRENT OVER FIXED PERIOD........................................................................................... 38
FIGURE 24: ENERGY DISCHARGED............................................................................................................................... 39
FIGURE 25: PROCESS OF USING HYBRID BATTERY IN SECONDARY APPLICATION........................................................ 43
FIGURE 26: ENERGY CAPTURING BY A SOLAR PANEL ................................................................................................... 44
FIGURE 27: SECOND-HAND HYBRID BATTERY IN UPS APPLICATION.......................................................................... 45
FIGURE 28: STATIONARY BIKE & HYBRID BATTERY ................................................................................................... 50
FIGURE 30: DEGRADATION LINEAR FIT OF BATTERY 2................................................................................................. 52
4. iii
LIST OF TABLES
TABLE 1: COMPARISON BETWEEN HYBRID BATTERIES AND FUEL CONSUMPTION (MPG) [2]......................................... 6
TABLE 2: TYPICAL NIMH BATTERY CHARACTERISTICS [16] ...................................................................................... 19
TABLE 3: TYPICAL CHARGE CHARACTERISTICS FOR FAST CHARGE [16]..................................................................... 24
TABLE 4: NOMINAL AND RECOMMENDED END-OF-DISCHARGE VOLTAGES UNDER NORMAL AND HEAVY LOAD. [9]..... 26
TABLE 5: CAPACITY & ENERGY OF ALL BATTERIES..................................................................................................... 31
TABLE 6: LAMP SPECIFICATIONS.................................................................................................................................. 39
TABLE 7: USEFUL ENERGY AND TIME OF DISCHARGING THE BATTERIES AT 1 AND 3 DC LAMPS................................ 40
TABLE 8: CATEGORIZATION OF TESTED HYBRID BATTERIES....................................................................................... 41
5. iv
NOMENCLATURE
C
V
̂
I
R
r
̂
ṁ
̇
ΔT
Charging/Discharging Rate [Colom]
Battery Voltage [V]
Discharge Starting-Voltage
Current through the Battery [A]
Battery Resistance in free mode [Ω]
Battery Internal Resistance [Ω]
Load Resistance [Ω]
First Resistance of Voltage Divider [Ω]
Second Resistance of Voltage Divider [Ω]
Mass Flow Rate [ ]
Volume Flow Rate [ ]
Specific Heat (J kgˉ1
K−1
)
Temperature Difference [C°]
7. vi
ABSTRACT
The use of HEV (Hybrid Electric Vehicles) showed a huge reduction on the reliance on natural
resources. In Jordan, the number of HEVs is high and still increasing, thus, the amount of stored
used Hybrid batteries also increases. By time, it is expected to have an enormous quantity of
those wasted and neglected batteries. Therefore, a plan must be implemented with the need of
reducing the negative effects that result in: costs of storage, high costs of recycling and the
danger of explosion for any reason.
This project is an evaluation process and repurposing of used Hybrid batteries. The aim is to
investigate the serviceability of those batteries after their life-cycle in the HEV application. The
project consists of two main sections; basically, the procedure starts in testing the batteries
through a scheme of charging/discharging, and analyzing the data in order to obtain the RUL
(Remaining Useful Life). After that, suitable secondary applications will be introduced, studied
and reviewed, and the batteries will fit to be used in those applications as modules or multiple
modules connected together. An RUL expectation of one category of the tested batteries is to be
made through a degradation test.
8. vii
ACKNOWLEDGMENT
We would like to offer our gratitude to our supervisors Dr. Ahmad Al Muhtady and Dr. Hani
Muhsen, who have supported us with their knowledge throughout our thesis. Without their
assistance and encouragement, the thesis would not have been completed.
Also, we would like to express our appreciation to Engineer Mohammad Ayyash, who has
helped us in understanding and programming the Arduino.
10. 2
PROBLEM STATEMENT
Nowadays, the world is concerned about new solutions to save natural resources. Hybrid Electric
Vehicles (HEV) have an apparent positive effect on energy saving in automobile in addition to
CO2 emissions.
When Hybrid batteries get old, they become inefficient for automobile due to loss of capacity.
Therefore, the remaining useful life (RUL) of these batteries in Automotive applications
becomes zero (and are piled in storages in Jordan as hazardous waste). In Jordan the number of
those untapped power sources is increasing and manufacturers are producing huge amounts of
new batteries annually. The cost of recycling those batteries is high and limited to certain
countries which have the necessary expertise for that. With this project, RUL is re-assessed
based on the fact that these batteries can still be value-adding in secondary applications. The
success of the project can have impacts both environmentally and economically.
A scheme of reusing the second-hand Hybrid batteries is to be suggested to extract further
usefulness out of these retired batteries, which would help reducing the number of stored
batteries.
OBJECTIVES
General objectives
Through this project, it is purposed to test NIMH hybrid batteries and analyze the characteristics
and to come up with a scheme of non-destructive test for the second-hand Hybrid batteries. The
test results would lead to know the battery status and its Remaining Useful Life (RUL). The
battery then is to be utilized in a secondary application.
Detailed objectives
The scheme of testing should be valid on all the batteries within the same type, with different
ages and status. With the purpose of determining the scheme elements and specifications, the
following subject matters should be studied:
11. 3
Degradation for the Hybrid battery after its vehicle’s life cycle
Battery types and specifications
Optimum parameters that affect batteries performance
Different test methods and concerned safety parameters
Different tests and test methods
Tests procedures and conditions
In order to gather the results of the test, an Arduino circuit should be set up to the testing scheme.
By applying the test, the batteries’ RUL are to be known by obtaining one of its parameters,
which are: battery’ SOC, SOH, REC, capacity or efficiency (compared to new cells).
Some recommendations and ideas for the secondary applications would be made, where the
second-hand Hybrid battery would be salvaged.
13. 5
BACKGROUND OF THE PROJECT
Over years, many scientists have been developing different ways of transportation in order to
make it cheaper, easier and more efficient. Automotive industry has one of the largest roles in
transportation. It has been relying on internal combustion engines which operate mainly on oil
fuels (Diesel, Gasoline, etc.). As known, oil fuels are non-renewable energy resources which
eventually will end. In addition to its impact on the environment and the human health from the
exhaust emissions which contains toxic gases such as, CO, SOx, NOx and CO2. Also, from the
financial side it became more costly to run these engines.
Hybrid Electric Vehicles (HEV) employ a secondary energy system comprised of batteries
charged through the use of regenerative braking in order to decrease the reliance on the energy
that is generated from by the internal combustion engines. In fully electric vehicles, this
secondary system becomes the only source of energy. In both cases, the energy reliance imposes
the availability of reliable large enough energy storages; namely batteries. When the battery ages
or exceeds a certain amount of cycles (Charging and discharging) in the vehicle, its level of
performance declines and it does not function as it is meant to be. These batteries are then retired
and new ones are brought in.
In 2000, the first hybrid vehicle was released in the United States. Up to now, so many types and
models of hybrid cars were produced by some manufacturers, Such as:
Toyota
Hyundai
Ford
Lexus
Audi
Each Manufacturer has invented a Hybrid system with one of three main types of Hybrid
batteries, which are:
14. 6
1) Lithium-Ion Batteries: They have high energy per unit mass relative to other types of
batteries. They also have a high power-to-weight ratio, good high-temperature
performance, high energy efficiency, and low self-discharge. Most components of
lithium-ion batteries can be recycled. Lithium-ion batteries are currently used in most
portable consumer electronics such as cell phones and laptops. Most Manufacturers of
plug-in hybrid electric vehicles use lithium-ion batteries.
Lithium-ion batteries have high costs and low life cycle compared to other batteries.
2) Nickel-Metal Hydride Batteries (NiMH): They offer reasonable specific energy and
specific power capabilities. Nickel-metal hydride batteries have a much longer life cycle
than other batteries and are safer. Due to this reason, These batteries have been used in
all-electric vehicles and used in some of the hybrid electric vehicles. The main
disadvantages of nickel-metal hydride batteries are their high cost, heat generation at high
temperatures, and high self-discharge.
3) Lead-Acid Batteries: They can be designed to be high power and are inexpensive, safe,
and reliable. However, they have low specific energy, poor cold-temperature
performance, and short life cycle. This type of Batteries is rarely used in Hybrid Electric
Vehicles. [1]
The table below shows a small comparison between some types of Hybrid cars in Jordan.
Table 1: Comparison between Hybrid batteries and fuel consumption (MPG) [2]
Hybrid Type Hybrid Battery
Fuel Economy
(City/Highway)
Toyota Prius NiMH 51/48
Toyota Camry NiMH 43/38
Honda Accord Lithium-ion 27/37
Ford Fusion Lithium-ion 44/41
15. 7
Lexus CT 200h NiMH 43/40
Hyundai Sonata Lithium-ion 40/44
The above cars have a number of modules in their Hybrid batteries in the range of 25-50
modules, where each module consists of six Hybrid cells.
In Jordan, the total number of Hybrid cars is 46,300 cars [3]. In addition to that, some of the
governmental institutions, for example: Greater Amman Municipality, parliament and
universities started to use hybrid and electric vehicles because of the importance of using it in
saving oil-based energy. In the German Jordanian University, recently, the president uses a plug-
in electric vehicle.
Figure 1: GJU president plug-in electric vehicle
This gives us an indicator of the huge number of present and future used batteries that will be in
the storage within the next five years. Those batteries will represent a concern in the country,
because they are neither cheap to properly store nor to fully recycle. Improper storing can
adversely affect the environment as these batteries contain hazardous materials.
Battery manufacturers define a battery’s end of its life as the moment it can only deliver up to
80% of its rated amp-hour capacity. They are then considered as non-useful batteries in HEV or
16. 8
EV [4]. Here, it becomes an evident of the need of determining the battery’s RUL and finding a
proper secondary application for using it.
Undesirable effects are produced on the batteries by time, which indicate that the battery has
aged. These undesirable effects include the loss of rated capacity, faster temperature rise during
operation, less charge acceptance, higher internal resistance, lower voltage, and more frequent
self-discharge. While the battery’s life is described by the battery capacity, maximum voltage it
can take and the effective internal resistance [5].
In order to see how do these undesirable factors affect the battery’s life and to find out the REC
of the battery, some tests could be done; Capacity test, Energy test, Delivered Power test,
Internal Resistance test, Temperature test, Maximum Voltage test and Maximum Current test.
Those tests could be done separately or merged. Voltage, current and temperature are considered
safety limitation parameters that should not be crossed when testing the battery. [6]
REC of a hybrid battery is dependent on several factors, that could affect the testing procedure,
which are;
Type of Vehicle
Number of cells
Age (number of cycles)
Operating conditions
Testing procedures could be summarized in measuring the capacity after the number of cycles
the battery went through (battery’s age) to know the battery’s status at that time. A method of
testing could be done by charging the battery and discharging it, with respect to safety
parameters limitations. With using certain software, testing parameters could be observed and the
data could be collected and compared to the manufacturer’s specifications, in order to obtain the
RUL of the battery.
Nowadays, there are very few testing schemes for the used hybrid batteries, most of it are
destructive tests, which rely on expensive components, circuitry, and software. Batteries OEMs
have not even standardized a scheme to test used batteries. There are only tests for new batteries
to validate the specifications of the battery and safety parameters.
17. 9
USABC (United States Advanced Battery Consortium) has created some procedures for
standardized testing of Hybrid batteries, but these tests are mostly destructive tests (the tested
battery no longer is functional) and are focused for out of the line newly produced batteries.
LITERATURE REVIEW
Hybrid batteries in HEV are charged by the kinetic energy of the car depending on the
regenerative braking, where electric motors are switched to generators. The energy is stored
temporarily in order to be used when needed under certain conditions. The levels of charging and
discharging the battery during the motoring and the braking modes define the capacity of the
battery, which can be measured throughout a test called "Energy Test". The amount of power
that is transmitted to the wheels from the battery through the electric motor can be measured by a
"Power Test". By the two tests mentioned above, the RUL of the battery can be also determined.
[6]
Many approaches of tests could be done to achieve the RUL of Hybrid batteries. Each test varies
from the other tests by the mechanism of charging/discharging or using variable devices. Some
research papers were introduced related to the testing approaches of Hybrid batteries.
Battery Testing and Life Estimation in the US [7]
The test procedures can be used on any size cell, module or battery and on battery technologies
at different levels of maturity. For Plug-in Hybrid Electric Vehicle (PHEV), there are three major
battery life/aging tests, which are:
Calendar Life Test
Charge-depleting Cycling Test
Charge-sustaining Cycling Test
Calendar Life
In this test, the battery is idle most of the time. A daily pulse is performed to gauge the health of
the battery. These tests are typically performed at a typical temperature range of 25 to 60o
C.
18. 10
Charge-depleting (CD) Cycling
This test emulates electric propulsion in a vehicle. The cycle life profile is started from a SOC of
90% and it is repeated until the goal charge depleting energy is totally removed.
Charge-sustaining (CS) Cycling
This test is performed continuously at a low SOC to emulate the operation of a PHEV in the
hybrid mode. It can be combined with the CD test by operating 50 profiles of CS with one
profile of CD in order to capture a better performance of the vehicle.
Reference Performance Tests (RPTs) consist of constant-current capacity measurements and
hybrid pulse-power capability (HPPC) at 30o
C. RPTs are performed every 32 days for Calendar
Life, 400 cycles for CS cycle life and 30,000 cycles for CD cycle life.
For Electric Vehicles (EV), there are two types of Life tests, which are:
Calendar Life test
Cycle Life test
Calendar Life
This test is similar to storage test. It is typically performed at low percentage of Depth of
Discharge (%DOD) and in a temperature range of 25 to 60 o
C.
Cycle Life
In this test, Daylight Saving Time (DST) profile is used and scaled for the power characteristics.
It is performed repeatedly many times, to discharge up to 80%DOD followed by recharging it
according to certain recommendations. If the temperature is increased, the rate of performance
decline will also increase.
RPTs are performed at 25o
C every 28 days for calendar life and every 50 cycles for cycle life. It
consists of constant-current capacity, DST-discharge capacity and a peak power test.
The voltage and current limits varies between the types of Hybrid batteries in normal conditions.
In NiMH battery, for example, the charging voltage is in the range of 1.4-1.6 V/cell, which
receives approximately 240 Volts in Prius HEV with a current of 30 Amps. In discharging, it
19. 11
gives a voltage of 14 V from the battery as a whole with a low current of 0.5 Amps. This
charging/discharging process’ operating temperatures range between 0 to 45o
C and -20 to 65o
C,
respectively.
Electric Vehicle Battery Test [8]
The United States Advanced Battery Consortium USABC has done several destructive tests on
new Hybrid packs, modules and cells. They have come up with a fast charge scheme. The
purpose of this test is to determine the fast charging capability and the efficiency of the battery
when charged by high rates. The USABC goal for fast charging is to return 40% of the SOC of
the battery, starting from 60% DOD, in 15 minutes. DOD then to be increased to 20%, and the
SOC to 80%).
This test is conducted normally as a series of cycles with the increase of fast charge rates. For
each charge rate, the following sequence of steps is performed:
1) After fully recharging the battery, discharge it to 60% DOD at a C/3 constant current
discharge rate.
2) Immediately recharge the battery at the selected charge rate until 40% of the rated
capacity (in Ah) has been returned.
3) Immediately fully discharge the battery at a C/3 rate to determine the amount of the
recharge available for use.
The test series terminates when (a) the 40% capacity in 15-minute charge rate is achieved;
alternatively (b) the battery temperature, voltage, or other operating limit is exceeded during
recharging mode. These tests are considered destructive tests that done to establish performance
and life targets for PHEVs. This means that the battery will be no longer useful after applying
this test.
An Aging Model of Ni-MH Batteries for Hybrid Electric Vehicles [5]
A research was done at The Ohio State University, Center for Automotive Research in order to
establish an accurate model of battery aging and life.
20. 12
It stated that time produced undesirable effects in batteries that result in the deterioration of their
performance, which in turn results in the deterioration of the HEV performance and fuel
efficiency. Research shows that the life of a battery is influenced by many factors. The most
important factors are extreme temperatures, overcharging, discharging, rate of charge or
discharge, and the DOD of battery cycles.
Figure 2 shows the relationship between the percentage of cycle life available and the change in
temperature.
Figure 2: Influence of temperature on cycle life [5]
Overcharging and over-discharging
some tests showed that over-charging Ni-MH batteries by 0.2 V will result in a 40% loss of cycle
life and a 0.3 V over-discharge of lithium-ion batteries can result in 66% loss of capacity.
Depth of Discharge
DOD is defined as the amount of capacity (Ah) removed from a battery cell expressed as a
percentage of the battery's rated capacity [9]. DOD is the opposite of SOC, where:
21. 13
Figure below shows that the cycle life is much greater when the DOD in each cycle is smaller. In
this example, the battery can last 5000 cycles if it is discharged by 10 % in each cycle, or 500
cycles if the DOD is 90 %.
Figure 3: Figure 3 Example of the dependence of the cycle life on the DOD [5]
Internal Resistance [5]
It is considered as a parameter to describe the decay of the characteristics of the battery.
An example of previous work done is the Aging experiments done on the Toyota Prius Ni-MH
batteries from Panasonic, in which a cycle is a simple discharge pulse, Figure below shows how
the capacity of the battery decreases as the number of pulse cycle increases, and how the internal
resistance increases as the capacity decreases.
22. 14
Figure 4: Aging data from the Prius Battery pack [5]
Internal resistance is one way used to track a battery’s SOH and RUL. As a battery ages, its
internal resistance will rise, reducing the battery’s ability to charge to a certain capacity.
However, the internal resistance of a battery varies with SOC and temperature.
This makes sense; when internal resistance (R) increases, the current (I) delivered to the battery
(useful for charging) decreases. This would also result in decrease of the capacity, as seen in the
equations below.
(2.1)
(2.2)
Operating the battery at elevated temperatures improves performance due to improved
electrochemical reactions, but prolonged exposure will shorten life. While Cold temperature
increases the internal resistance, and lowers the capacity.
The internal resistance of the battery can be measured by the equation below:
23. 15
̂ (2.3)
̂ (2.4)
̂ (2.5)
̂
[10] (2.6)
Figure 5: Discharging Cycle with internal resistance [11]
Test termination
The test is terminated when one of its parameters limits is reached. Those parameters are:
[12]
(Hybrid Batteries mechanic)
[13]
[14]
[12]
24. 16
IMAX B6 charger [12]
Imax-B6 is a rapid charger that contains a high performance microprocessor, and it has an auto
function to control the charging rates during charging and discharging. Also, operating modes of
this charger are controlled between the charger and the battery to reach maximum safety. All the
settings are easily configured by the user.
The manufacturer of IMAX B6 has determined rated voltage and current values for charging and
discharging the battery. According to that, the rated values for the module that is being tested in
the project “NiMH hybrid battery” which consists of six cells are:
Rated Charging Values
Current: 5 A
Rated Discharging Values
Current: 0.56 A
25. 17
Battery Degradation [15]
A test was done on 26 new Lithium-Ion Batteries for 400 cycles of charging/discharging to
ensure the reliability of this type of batteries.
Figure 6: Twenty six different lithium-ion battery capacity degradation data [15]
This figure illustrates the degradation of the capacity that occurs when the cycles are increased.
In this test, an exponential fitting was drawn to determine the RUL which was in the range of
(235 to 283), and the error which was 3%, according to this equation.
(2.7)
27. 19
BATTERY TESTING
The first step of the project was to survey local automotive shops in order to identify the current
market in terms of used batteries, methods of storing it, and disposing of it. During this step, a
general background information about the batteries used in hybrid electric or hybrid vehicles
were set up, where all hybrid batteries types and their manufacturer’s specifications were studied
and compared. Standard operating conditions are identified in this stage. Table below shows
manufacturers specifications for NiMH Hybrid battery.
Table 2: Typical NiMH Battery Characteristics [16]
Parameter Typical Value
Nominal Voltage 1.2 V
Open circuit voltage 1.25 – 1.35 V
Typical end voltage 1.0 V
After studying the test parameters, it is found that the Imax B6 is the most appropriate and
available device to be used for testing the batteries in a non-destructive way, so that the battery
can be tested without ruining its performance and it can be used again after this test. The test
involves three cycles of charging and discharging, which in each iteration it is more capable of
revealing the new RUL.
A testing scheme for the batteries is experimented after that. This scheme, which comprises of
several charging and discharging cycles under controlled conditions will be used to bench mark
the used batteries against new ones. The status of the used batteries can then be determined. The
effectiveness of the scheme will propel change in the circuitry in order to achieve better results; a
procedure that hinges on experimentation.
In order to make an interaction between the IMAX B6 and the software, an Arduino circuit was
developed. The Arduino saves data every second by using Voltage, Current, and Temperature
sensors.
28. 20
Figure 7: Preliminary Testing Circuit of the Used Battery
Arduino Sensors
Temperature sensor [17]
The temperature sensor that was used in this project is an IR sensor MLX-90614.
It reads the ambient temperature and the batteries temperature without any contact, and its range
is between -40 to 85 Celsius.
Current Sensor [18]
The current sensor ACS712 5A is connected in series to the circuit as shown in the Scheme
(figure 2). It measures the current in the range of -5 to 5 A.
Voltage Sensor [19]
A voltage divider was built as a secondary electrical circuit to measure the instantaneous voltage,
which the test is operating with. The voltage divider used in this case consists of two resistors
connected to the Arduino from one end. The other end of the smaller resistance is connected to
29. 21
the battery, while the bigger resistance's end is connected to the ground as shown in figure [8].
The magnitude of the two resistors are calculated as follows:
Figure 8: Voltage Divider
(3.1)
Where:
[20]
[12]
30. 22
The value of was assumed to be 4.7 KΩ, so:
The values of the resistors are very high; so, the current would be very low, according to their
negative proportional relationship, and that would increase the safety of the sensor without
affecting the reading.
(3.2)
The following are real figures of the testing circuit that was made at the GJU campus.
Figure 9: preliminary Hybrid Battery testing scheme
32. 24
Figure 12: Voltage Divider
Figure 13: Infrared Temperature Sensor
Charging the battery
Manufacturer of NiMH hybrid batteries have specified typical charging characteristics, those
characteristics are shown in the table below:
Table 3: Typical Charge Characteristics for Fast Charge [16]
Parameter Typical Value
Charge time 1.5 – 3 hours
Charge current 0.5 – 1 C
Charge efficiency 70 – 90 %
33. 25
Charge voltage 1.4 – 1.6 V
Temperature range 5 … 60°C (max)
The IMAX B6 is supplied by a DC Power supply in a range of (11-18 V) [12]. Then it delivers
current to the tested battery. The voltage applied to the battery will always have to be slightly
above the battery voltage at any given moment in order for the battery to charge, where the
maximum voltage that can be applied to the battery is in the range of 1.4-1.6 V / cell. In our case,
the NiMH module voltage consists of six cells, so:
(3.3)
[21]
So, the maximum voltage that the battery can take is 9.6 V charged with a current of 3.25-6.5 A.
(3.4)
[16] (3.5)
This means, if the applied voltage was above 9.6 V, this can lead to a serious damage in the
battery, and it will cause the battery to explode and release dangerous chemicals and gases that
may cause fire. To ensure safe charging of the batteries, they are charged up to 9 V as it is the
rated maximum voltage set by IMAX B6 manufacturer. The test is manually stopped when the
battery reaches the maximum voltage in order to avoid overcharging of the battery.
Charging the battery should be immediately stopped when the temperature of the module reaches
45 Celsius degrees [7] or increases in the rate of one Celsius per one minute [16]. The Arduino is
programmed to stop the test when one of these two possibilities occurs.
34. 26
Time of charging the battery is dependent on the capacity of the battery as well as the internal
resistance. In other words, the duration of charging the battery varies between different batteries
due to their different SOH and REC.
Discharging the battery
1. Discharging by IMAX B6
IMAX B6 is set to discharge the battery when it is fully charged with a rated current of 0.56
A, as mentioned before. The battery is discharged at a high DOD in order to ensure that the
battery is fully discharged, and end-of discharge voltage is set to be 5V in the IMAX B6.
According to:
Table 4: Nominal and recommended end-of-discharge voltages under normal and heavy load. [9]
2. Discharging by resistive load
The same connection setups are set as in discharging by IMAX B6. The batteries are
discharged at a higher rate, and connected to a higher load than the one in IMAX B6. A
discharging circuit that consists of 3 lamps is connected to the battery. The lamps are
connected in parallel, to consume more current from the charged battery, and have the
following specifications:
35. 27
The Arduino circuit, after all, is not affected; that is because it is connected to the battery
through the discharging circuit, but not connected mainly to the load or device. Figures [14-
15] illustrate the circuit of discharging using one and three lamps, respectively.
Figure 14: One-lamp resistor discharging
Figure 15: three-lamps resistors discharging
36. 28
Time of discharge is dependent on the age of the battery, the reason why new batteries take
longer time than older batteries to get discharged and this is due to the loss in capacity.
Test Monitoring & data analyzing
An Arduino circuit, as mentioned before, is connected between IMAX B6 and the Hybrid
battery, with the aim of monitoring the performance of the battery while charging and
discharging. In order to ensure safety of the test, the Arduino is programmed to terminate the test
when one of the safety parameters is exceeded. As well, the Arduino reads electric signals and
converts it to readable values of the test parameters (current, voltage and temperature)
The Arduino is programmed in Matlab, and is able to read different types of data and show it on
the screen instantaneously by using the Arduino Software. At the same time, data is stored in a
memory card, that can hold a large amount of data and sort it in tables using Microsoft Excel.
This is also a part of programming the Arduino.
The measurements is then analyzed, compared to the manufacturer's specifications of the battery
and benchmarked against new batteries’ performance during the same test in order to obtain the
RUL of the tested battery. All readings are taken with respect to time and the parameters can be
observed and integrated, in order to obtain other results that might be helpful to obtain the RUL
of the battery.
The capacity of the battery can be observed from its performance in the test. It can be determined
in three different ways, which are:
1) Using IMAX B6, which displays the charged and discharged capacity of the tested
battery after the test in [mAh].
2) The integration of the current line against time along the test, and the capacity would
equal the area under the curve.
3) Discharge capacity at a constant rate.
[Ah] [22] (3.6)
37. 29
As a result of charging and discharging the battery, the energy that it has consumed while
charging and delivered while discharging can be measured as follows:
∫ [Wh] (3.7)
And the power can be calculated from the following equation:
[W] (3.8)
Battery's temperature was monitored by an infrared sensor (IR) connected to the Arduino, and
placed inside a box, which is designed to insulate the battery and for safety purposes.
Figure 16: Safety Box
This type of test is performed at low temperatures, thus, the heat dissipated by the battery to the
surrounding air was NEGLIGIBLE! Heat gained by the surrounding air by convection can be
calculated by this equation:
Sample calculation for
̇ (3.9)
[ ] [ ] [ ]
39. 31
In this chapter, the results of testing 12 used NiMH hybrid batteries are benchmarked with a new
battery. The results of the three tests are shown and presented in tables as follows.
Table [5] illustrates the results of the tested batteries. It is observed that the capacity and energy
while charging/discharging of used batteries vary between the new battery, and this is due to the
increase of the used batteries’ age (in cycles) as mentioned before.
Also, Battery 5 and Battery 7 have been swollen during the charging cycle which led to
discontinue the for safety purposes. While the reason in swelling can be summarized irregular
electro-chemical process that lead to an expanding in size of the electrodes and separator in the
Hybrid battery. Note that swelling would lead to accelerated degradation, because of mechanical
instability.
Table 5: Capacity & Energy of all batteries
Figure [17] shows the number of batteries in each range of the relative energy capacity.
40. 32
Figure 17: Relative Energy Capacity Histogram
Figures [18-23] show the differences in the performance while charging and discharging for
three used batteries of different categories, and benchmarked to the new battery.
CHARGING RESULTS
Figure [18] shows how the used batteries have reached the termination voltage of charging in a
very small time period in comparison with the new battery.
Battery 5 showed a good behavior before it was swollen and damaged. Also, at the beginning of
the test, the voltage of battery 2 was increasing as the new battery, but the loss of capacity led to
have a high-slope curve and the battery has reached the maximum voltage faster. However,
battery 8 reached the maximum voltage a little bit earlier than battery 2, its voltage-vs-time
relationship curve shows that the capacity is way too small.
41. 33
Figure 18: Charging Voltage vs. Time
Batteries are usually charged with a maximum current of what they can withstand. From Figure
[19], it is noticed that the ability of used batteries to receive current is less than the new battery.
It is observed also that the capacity of used batteries is less than the new battery since the
capacity is the integration of the current over time ( ∫
42. 34
Figure 19: Charging Current vs. Time
Figure [20] shows the amount of energy in [Wh] that each battery has stored in the charging
process. While the energy can be calculated by integrating the power over time, as shown in the
methodology.
43. 35
It is recognized from the graph that the charging energy to the used batteries is small in contrast
to the new battery. The reason is that the energy of the battery is proportional to its capacity; the
more the battery has a capacity for electric charges, the more energy it would take. As a result,
Battery 8 showed that it has the lowest energy because it has the smallest capacity that also led to
decrease the time of charging.
Charging Energy is an effective parameter for determining the energy that can be stored in the
Hybrid battery in each cycle when used in a secondary application.
Figure 20: Energy charged to the batteries
44. 36
DISCHARGING RESULTS
Discharging the batteries was done at different rates. First, IMAX B6 was used to discharge the
batteries at low rate, and then DC lamps were used to discharge at higher rates.
o IMAX B6 (0.5 A)
According to figure [21], the three batteries have showed three different discharging
performance of discharging at the same rate. That indicates to the difference of REC between
those batteries. With comparison with the new battery, all the batteries have been discharged to
the same volt limit with less time.
The behavior of Battery 2 in discharging is similar to the new battery, but with higher slope
because of time difference, while battery 5 had a voltage from 8.25V to start the discharging at
6.5 V. That is, as mentioned before, due to the deformation of the internal components of the
battery. [23] Furthermore, battery 8 was discharged linearly with a higher slope because of its
small capacity.
Figure 21: Discharging Voltage vs. Time
45. 37
Figure [22] shows that aging of the battery does not affect or limit the discharging current. That
is basically because the charges are removed from the battery at a rate of what the load can
sustain. But there is always a maximum rate to ensure that the batteries are in the safe zone, and
none of the batteries have exceeded that limit.
NOTE: The gaps shown in the figures are due to different scales of time between the batteries.
Figure 22: Discharging Current vs. Time
Figure [23] Shows that the batteries have the same density of discharging current pulses when
the period is fixed.
46. 38
Figure 23: Discharging Current over Fixed Period
In figure [24], the discharged energy [Wh] is plotted against time [min]. The discharged energy
can be defined as the useful energy that can be extracted from the battery during the operation
time, at a constant rate of discharging.
It is observed that the used batteries supply less energy than the new battery. For example,
Battery 8 can only supply 3.14 [Wh], which limits the varieties of the secondary application in
which to be powered by this battery. Also, REC of the used batteries can be determined by
referred to the new battery. For example, REC of battery 2 is:
(4.1)
NOTE: Table [5] shows the REC of all batteries.
47. 39
Figure 24: Energy Discharged
DC lamps (1.35 and 4.15 A)
This method was used to investigate the performance of the tested batteries at different constant
rates. Lamp specifications are shown in the table below (for each lamp).
Table 6: Lamp specifications
Voltage [V] Power [W] Current [A]
12 21 10
48. 40
Table [7] summarizes an average of three cycles of the output energy from the tested batteries at
1 DC lamp and 3 DC lamps, with the a current of 1.35A, 4.15A, respectively.
Table 7: Useful Energy and Time of Discharging the Batteries at 1 and 3 DC Lamps
It is noticed that the time of discharging using 3 DC lamps is less than using 1 DC lamp by a
third. And as compared to table [5], discharging time using 1 DC lamp is 13 the time when
using IMAX B6.
Also, it is concluded that the useful energy decreases when the discharging rate increases, and
that is due to the increased resistance and losses in the wires.
In addition to that, those values would give an indicator on the appropriate secondary application
that the second-hand battery might serve at.
49. 41
BATTERIES CATEGORIZATION
Based on the REC, capacity and the useful energy of the tested batteries, and according to the
results of table [5], the batteries were divided in three categories.
Category A, which includes the battery with the higher value of REC
Category B, which includes the batteries with the medium range of REC, energy and
Capacity
Category C, which includes the batteries low discharging-energy and capacity.
Table 8: Categorization of Tested Hybrid Batteries
51. 43
Hybrid battery's lifecycle is not limited to its period in automotive application. It is considered
useless in automotive when it serves a certain number of cycles, but in fact, it is still serviceable
in other applications as second-hand batteries with a new life period. Second-hand Hybrid
Batteries can be used instead of new batteries in general applications, where it can be charged.
This is in order to verify the establishment of a new usefulness and thus a new RUL for the
battery. The batteries are to operate as energy sources when it is needed.
Batteries Connection
Second-hand Hybrid batteries can be connected in two different ways; Parallel and Series. That
would increase the useful energy that can be used in the application.
The way of connection depends on the application. In some applications, it is required to use a
high voltage, low current batteries, thus, series connection is used. While in parallel connection,
batteries operate at low voltage and gives high current, and the energy remains as high as in
series connection.
The scheme below shows the process of repurposing the second-hand batteries in secondary
applications. The batteries first should be charged by any of the energy sources, and it will
preserve this energy until a later-use secondary application. In this chapter, two of the method of
charging the batteries and some ideas for secondary applications will be introduced.
Figure 25: Process of using Hybrid Battery in Secondary Application
52. 44
SOLAR POWER
Solar panels capture the energy from the sun ,which can be used directly as an electricity source.
It can also be used to charge and store energy in the hybrid batteries, this energy can be used
after the sun sets. Also, this technique is very useful for areas with a high number of hours of sun
shine per day.
The average energy that can be produced by a solar panel is 1000 Wh per day
[24]. The process of the capturing the energy is shown in the figure below.
Figure 26: Energy capturing by a solar panel
The following are examples of real applications, where this system can be implemented:
53. 45
1. House application UPS
The following 3 floors house carries an Uninterruptible Power Supply that can feed
power to the critical equipment in the house in case of power outage. Those critical
equipment consist of:
Lights
Refrigerator
Elevators
Security System
Figure 27: Second-Hand Hybrid Battery in UPS Application
The following calculations are done, in order to find the total energy needed by the
critical equipment. So that the number of needed second-hand Hybrid batteries would be
obtained.
Lights
Power of the CFL is 15 W. In order to be able to power 10 CFL's for 3 hours, the
energy needed is 450 Wh. [25] This is as follows,
[ ] [ ]
By dividing this value by the average Discharged Energy of the tested batteries,
the number of batteries of each category is then obtained.
54. 46
-
[ ]
[ ]
-
[ ]
[ ]
-
[ ]
[ ]
Refrigerator
Energy consumption of a modern refrigerator is 28 KWh per month, assuming 30
days per month and 24 hours of operating per day, the instant energy that is
consumed by the refrigerator can be calculated:
[ ]
[ ]
So, to power the refrigerator for 3 hours, an energy of 116.7 Wh is needed. [26]
[ ] [ ]
-
[ ]
[ ]
-
[ ]
[ ]
55. 47
-
[ ]
Elevator
Elevators should have backup power supply in case of power outage so the
elevator can be landed to the ground floor. The annual power needed for an
elevator that can hold up to 580 Kg inside 3 floors house, assuming 365 days per
year and 24 hours per day is
In power outage, it is only needed to operate the elevator for a couple of minutes
to ensure it has landed on the ground floor. Time of operation is taken in this
project as 15 minutes. [27]
[ ] [ ]
-
[ ]
[ ]
-
[ ]
[ ]
-
[ ]
56. 48
Small Security System
The basic components for a Home Security System to be powered are:
- DVR and Video Cameras. Power consumption = ( 40 W) [28]
- Motion Sensor. Power Consumption = ( 150 W) [29]
The net power needed for the security system is 190 W. So, If it is to be powered
for a maximum 1 Hour, the energy needed then is 190 Wh.
-
[ ]
[ ]
-
[ ]
[ ]
-
[ ]
2. Army Towers Application
Solar panels could also be used as an energy source in military fields. The figure below
shows an army tower, which is placed in the desert. Such a tower should be placed along
with the country's boundaries in order to support in protection.
Soldiers that serve in these towers need some electrical devices that have high costs of
electricity production along with all the towers. A solar panel system can be installed to
capture the solar energy during the day, and use it during the night. Second-hand Hybrid
Comment [D1]: Figure is to be
added (design under construction!!)
57. 49
batteries have proved that they can be implemented in this type of applications providing
an additional service of their lifecycle, after their automotive period.
The main electrical devices that a soldier can use in this tower, and their usage of
electricity during 6 hours in the night are as follows:
Light [25]
[ ] [ ] [ ]
Table-Fan [30]
[ ] [ ] [ ]
Small Refrigerator [31]
[ ] [ ] [ ]
Woki Toki Charger [32]
[ ] [ ]
This makes the total energy equals to the summation of the energy, which is equal
to
With this amount of energy, a number of Hybrid batteries are needed in order to
store it. The number of second-hand Hybrid batteries from each category is as
follows:
-
[ ]
[ ]
-
[ ]
[ ]
-
[ ]
58. 50
MECHANICAL POWER
Another example is the use of mechanical power to charge the battery. A designed paddle wheel
produces kinetic energy, which is collected by a dynamo; the dynamo transmits electrical power
to the battery, which can immediately or at a later time transmit this power to run an electrical
device. By using this implementation the energy in its various shapes can be stored and reused.
An average user can produce 100 W in an hour of exercising on a stationary bike with a 0.45 m
diameter flywheel. [33] The process of storing the energy in the second-hand Hybrid batteries is
shown in the figure below.
Figure 28: Stationary Bike & Hybrid Battery
The number of the tested Hybrid batteries that are needed to collect the produced energy by the
flywheel is as follows:
For category A (9.57 Wh)
[ ] [ ]
[ ]
For category B (5.56 Wh)
[ ] [ ]
[ ]
For category C (3.388Wh)
59. 51
[ ] [ ]
[ ]
Second-hand Hybrid batteries could be connected in series or parallel, as mentioned before. This
is in the purpose of having a variety of operating different devices at the gym, or at home.
DEGRADATION
A degradation test was conducted on 25% REC battery to ensure the capability and reliability of
this battery when used in a secondary application. It was a 60 cycles of charging/discharging and
the RUL will be calculated in accordance to the obtained data.
Figure [30] shows the linear fitting of the data with extracting some of the faulty results.
Exponential fitting is normally used for determining the RUL. But in this case, the battery is in
linear region which is the end of life region.
60. 52
Figure 29: Degradation linear fit of Battery 2
From this graph, the fitting equation is:
So, to calculate the RUL of the battery in cycles:
So, according to the results that was obtained from this test, the 25% REC battery could be used
once a day in a secondary application for around 6 months.
62. 54
PROJECT SUMMARY
In this project, it was desired to remodel a new lifecycle for used Hybrid batteries from HEV
applications. The evaluation of batteries’ performance was needed, and then benchmarked with
the initial status with the reason of determining the RUL of the batteries. Finally, it was required
to introduce reasonable secondary applications, where the second-hand Hybrid batteries find a
new life span.
The most difficult part of the project was creating a scheme of evaluating the batteries RUL,
since all the past research papers have shown the behavior of new batteries and considered
destructive tests. Testing procedures were not done in a controlled area, which led to have some
errors in the results. In addition, there was a risk taking of battery explosion; the defective
batteries could only be detected during the test.
Throughout the project, knowledge of Hybrid batteries types and experience in batteries testing
were acquired. Also, electrical concepts were enhanced, and we became familiar with connecting
an arduino circuit with several sensors to a testing circuit. Additionally, data analysis was
practiced by collecting the data, plotting the curves and obtaining the results from those tables of
data. As a consequence, personal skills were gained, such as; research method, technical writing,
project management and team working.
As a result of the project, it is concluded that a Hybrid battery's lifecycle is not limited to its
period in automotive application, but it can be used as second-hand batteries for lighter
secondary applications. The advantage of energy generation methods could be used with the
purpose of storing energy in the second-hand batteries. If one battery’s capacity is not enough to
store the energy produced, a number of batteries of different categories could be connected in
different ways to obtain larger capacity; thus larger energy.
Degradation curve shows that a 25% REC battery can sustain up to 184 cycles of operation. This
means that if the battery is being charged by any of the energy generation methods and then
discharged once a day, it would serve for approximately 6 months. This indicates that the battery
63. 55
came out from trash to serve for more half a year. It is noticed that excessive use of Hybrid
batteries in HEV would lead to have defective batteries that cannot be reused due to accelerated
degradation. Also, from the degradation curve, it is observed that sometimes, fault alerts of a
battery’s capacity/life would arise due to testing errors. Therefore, it is recommended to do
several trials when investigating a battery’s RUL.
RECOMMENDATIONS AND FUTURE WORK
It is recommended to test the batteries in a controlled space and to build a charging/discharging
circuit, taking into consideration automatic termination of the test in order to get better results
and increased safety. The controlled space consists of an insulated box and measuring sensors.
Also, it is recommended to monitor the chemical reactions of a battery during the test to observe
any abnormal behavior, such as swelling. In addition to that, an internal-resistance test could be
conducted; this would assist measuring the REC of the battery.
Furthermore, it is recommended to increase the variety of the tested batteries and to apply
degradation test on more sample batteries.
More than that, as a future work, it is expected to improve and apply the secondary applications
with the intension of proving the concept.
Reconditioning the batteries would increase the capability of storing and supplying energy,
which in its role, would increase the variety of the possible effective secondary applications.
64. 56
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