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Proceedings ArticleDOI

Development and realization of lithium-ion battery modules for starting applications and traction of off-road electric vehicles

27 Sep 2013-World Electric Vehicle Journal (Multidisciplinary Digital Publishing Institute)-Vol. 6, Iss: 3, pp 1-10

Abstract: The paper describes the development and realization of standard battery modules 12 V, made by LiFePO4 cells selected in a previous study by ENEA and the University of Pisa. Module means the group of four cells series connected, the electronic battery management system, the thermal management system and the mechanical case. Standard means that the same battery module can be used for different applications: in fact, the previous study showed that three standard battery modules, 30 Ah (little size), 60 Ah (medium size) and 100 Ah (large size), are sufficient to reach the levels of voltage/capacity requested by the most part of the applications in the field of the starting/auxiliary supply batteries (also for the nautical sector) and traction of off-road electric vehicles. More units of standard modules can be series/parallel connected to build complete battery systems able to satisfy the required performances. The development and realization of the modules mostly consisted of testing the selected cells to verify their suitability for the above mentioned applications, to make a thermal battery characterization so to define the thermal management system, to develop an electronic battery management system and to build a mechanical case. The paper shows all these aspects in detail.
Topics: Automotive battery (65%), Thermal Battery (55%), Lithium-ion battery (52%), Voltage (50%)

Summary (4 min read)

1 Introduction

  • These vehicles include mobile work machines for various applications, such as building sites, earth moving, street cleaning, as well as agriculture, horticulture, greenhouse, and gardening.
  • A recent study made by ENEA on the Italian market for mobile work machines gives a good idea of the relevance of these kinds of vehicles and the impact of their electrification [4].
  • On the other hand, 12 V is the standard voltage for starting batteries and the LiFePO4 chemistry was proved to be the best solution for the application as starting lighting ignition batteries [5].
  • Thus, the defined standard module can also be used as starting lighting ignition battery instead of the equivalent lead battery and this is another important factor of standardization.
  • Max continuous current [A] 180 Peak current @ 60 sec [A] 300 Cut-off voltage [V] 2.5 Charge @ +23°C Charge method CC/CV (3.65V).

2 Electrical Battery Test

  • Some samples of the selected batteries were tested under EUCAR procedures to verify the performances and the suitability to be used in the above mentioned applications.
  • The testing activities were performed at the Battery Test Room of the “Low Environmental Impact Vehicles Laboratory” at ENEA Research Centre “Casaccia” by means of battery testers and climatic chambers.
  • The following tests were performed: energy and capacity at different current rates and temperatures: in particular each sample was discharged with current rates respectively 1C, 2C, 3C at the temperatures 0 °C, +23 °C and +40 °C; fast charge, according to the manufacturer’s specification about the maximum continuative charging current rate, 1C, which theoretically corresponds to the complete charge in one hour; internal resistance; cold cranking test to evaluate the suitability of the batteries for the application as starting lighting ignition batteries.
  • The test was performed following the standard CEI EN 50342-1 “Lead batteries for starting applications – Part 1: General rules and test methods” adapted for lithium batteries.
  • The test results, resumed in the following figures, show the good behaviour of the cells and confirm their suitability for the selected applications.

2.2 Fast charge

  • The fast charge test consisted of a charge type CC/CV (constant current/constant voltage) @ 1C, according to the specifications of the manufacturer.
  • The voltage, current and temperature of the sample were monitored and registered during the test.
  • A typical example of the test results is shown in Fig. 3. EVS27 International Battery, Hybrid and Fuel Cell Electric Vehicle Symposium 4.

2.3 Internal resistance

  • The internal resistance is an important factor affecting heating and efficiency of the cell.
  • The test is made by three current pulses, separated by little rest periods: the first and the second pulses are at 1C current rate, the first in discharge and the second in charge, while the third is in discharge at the maximum current value which can be used for 30 s, according to the manufacturer.
  • Fig. 5 shows a typical voltage and current profile registered during the internal resistance test and Table 4 gives an example of the results for a cell with capacity 100 Ah, at SOC 50 %, and IHCE current 500 A.
  • The internal resistance test gave good results and the values obtained agree with the specification of the manufacturer.

2.4 Cold cranking test

  • To qualify the standard modules as starting batteries, it was decided to verify the starting performance.
  • In contrast, there is not a standard for lithium batteries: for this reason, it was applied the standard CEI EN 50342-1 with some adaptations.
  • The standard requires to completely charge the battery, to make a rest of 24 h, to put the battery in a climatic chamber at the temperature -18 °C, to make a discharge at current Icc (starting current, usually called Cold Cranking Ampere, specified by the manufacturer of the lead battery) within 2 minutes after the end of the cooling phase.
  • After 10 s of discharge, the battery EVS27 International Battery, Hybrid and Fuel Cell Electric Vehicle Symposium 5 voltage must be measured and verified that it is not lower than the minimum voltage specified by the manufacturer and the current must be interrupted.
  • The authors performed the test at -10 °C, rather than at the really limit condition of -18 °C, because it seems to be a more realistic situation but hard enough at the same time.

3 Thermal Management

  • The electrical characterization tests at low temperatures showed that the cells do not need to be heated during the operation in cold conditions, so the thermal management system of the module is only a cooling system.

3.1 Thermal battery characterization

  • A thermal analysis on single cell level was performed to study the thermal distribution during charge and discharge without thermal conditioning and to evaluate if battery cooling during operation is needed.
  • This was realized by the means of thermocouples and a thermo camera 320 x 240 pixel with thermal sensibility less than 0,1 °C.
  • A “hot point”, where the highest temperatures are registered, was identified under the negative pole.
  • The thermal analysis also showed that the critical temperatures are reached only very close to the end of discharge at the maximum current rate, so this is the only phase where battery cooling is really necessary.
  • Fig. 8 shows the typical temperature profile registered during a discharge at 300 A followed by a rest of 3600 s and a standard charge (CC/CV @ C/3) for the cell with capacity 100 Ah.

3.2 Cooling plant with air

  • An experimental test bed was realized to evaluate the performance of battery cooling by air.
  • The plant is a duct equipped with two blowers at the inlet section.
  • The fan speed is regulated to permit different air flows.
  • A right angle turn is used to create turbulence and mixing of the EVS27 International Battery, Hybrid and Fuel Cell Electric Vehicle Symposium 6 flow.
  • Fig. 11 shows the position of the thermocouples on the cells: each cell is equipped with two thermocouples (one on each side of the cell) under the negative pole, where the thermo graphical analysis gave evidence of a hot point, and two thermocouples (one on each side of the cell) are positioned in the middle of the two central cells, which are expected to be unfavourable as regards the thermal exchange.

3.3 Cooling plant with water

  • A simple cooling circuit was realized using a cup with a water inlet and outlet.
  • The water inlet is at the bottom of the cup, so that it cannot create waves and damage the cells.
  • The water’s level is about 1cm lower than the top layer of the cells, where the poles are situated.
  • The position of the thermocouples is the same of the previous plant.
  • Also the monitoring and data acquisition system is the same of the cooling plant with air.

3.4 Cooling tests

  • The cooling tests were realized during the working of the batteries in the most critical operating conditions suggested by the manufacturer of the cells and confirmed by the electrical characterization: this happens at current rate 1C in charge and 3C in discharge.
  • The results are shown in Fig. 13 and Fig. 14.
  • EVS27 International Battery, Hybrid and Fuel Cell Electric Vehicle Symposium 7.
  • Both cooling systems proved to be efficient, in fact the temperature remained under the safe limits declared by the manufacturer of the cells (+65 °C) and especially under the values registered in the similar tests performed during the thermal characterization without any cooling.
  • The comparison between the two cooling fluids is in favour of water: in spite of this, air was chosen as medium for the cooling system in the battery modules, because it is anyway efficient but simpler and more economic than a water cooling system.

4 Battery Management System

  • A proper battery management system (BMS) with active balancing was developed by the University of Pisa in cooperation with ENEA [3], [6], [7].
  • It provides the functions of protection, monitoring, data acquisition and active balancing of the state of charge of the cells.
  • The converter input is the total voltage of the module (12 V) and its output is connected through a switch matrix (as shown in Fig. 15) to the lowest charged cell of the module.
  • When more modules are series connected to create a complete battery system, it is possible to transfer energy from a module to another of the chain: in this configuration, one electronic board is the master of the chain.
  • EVS27 International Battery, Hybrid and Fuel Cell Electric Vehicle Symposium 8.

5 Realization of functional prototypes

  • The battery module contains four cells, the electronic board BMS, the power and signal internal connections, the fans for the battery cooling and the connector to realize the external communication (with other modules if slave, PC, charger or vehicle control unit if master).
  • All the modules have an NTC sensor on each cell, situated where the thermo graphical analysis put on evidence the hot point, and three fans (each one 34.5 Nm 3 /h 75.5 Pa @ 7000 rpm) on the cover of the case, which starts working when the temperature detected on a cell of the module is equal or bigger than +45 °C (this value is settable): the cooling system is optimized for the 100 Ah module and oversized for the 30 Ah and 60 Ah modules, but the cooling system is maintained the same for any type of module as another factor of standardization.
  • The placement of the cells inside the little and medium size module is different from the large size module due to the optimization of the geometrical factor.
  • Table 5 resumes the final characteristics of the modules.
  • EVS27 International Battery, Hybrid and Fuel Cell Electric Vehicle Symposium 9.

6 Conclusions

  • A little size battery module (30 Ah), a medium size battery module (60 Ah) and a large size battery module (100 Ah) were realized for the application in the field of off-road electric vehicles: the voltages (48, 96, 192 V) and capacities (120, 180 Ah) of this type of vehicles can be obtained by the series/parallel connection of the standard modules.
  • As a demonstrator, a complete battery system 48 V – 100 Ah was also realized: it is made by four modules large size series connected, each module has its own BMS, one module has the master function.
  • The modules can also be used as starting lighting ignition batteries instead of the equivalent lead batteries.

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EVS27 International Battery, Hybrid and Fuel Cell Electric Vehicle Symposium
1
EVS27
Barcelona, Spain, November 17-20, 2013
Development and realization of lithium-ion battery
modules for starting applications and traction of off-road
electric vehicles
F. Vellucci
1
, G. Pede
1
, F. D’Annibale
1
, A. Mariani
1
,
R. Roncella
2
, R. Saletti
2
, F. Baronti
2
, G. Fantechi
2
1
Italian National Agency for New Technologies, Energy and Sustainable Economic Development (ENEA), Via
Anguillarese, 301 00123 S. Maria di Galeria (RM) - ITALY, francesco.vellucci@enea.it
2
University of Pisa, Via G. Caruso, 16 56122 Pisa ITALY, roberto.roncella@iet.unipi.it
Abstract
The paper describes the development and realization of standard battery modules 12 V, made by LiFePO
4
cells selected in a previous study by ENEA and the University of Pisa. Module means the group of four
cells series connected, the electronic battery management system, the thermal management system and the
mechanical case. Standard means that the same battery module can be used for different applications: in
fact, the previous study showed that three standard battery modules, 30 Ah (little size), 60 Ah (medium
size) and 100 Ah (large size), are sufficient to reach the levels of voltage/capacity requested by the most
part of the applications in the field of the starting/auxiliary supply batteries (also for the nautical sector) and
traction of off-road electric vehicles. More units of standard modules can be series/parallel connected to
build complete battery systems able to satisfy the required performances.
The development and realization of the modules mostly consisted of testing the selected cells to verify their
suitability for the above mentioned applications, to make a thermal battery characterization so to define the
thermal management system, to develop an electronic battery management system and to build a
mechanical case. The paper shows all these aspects in detail.
Keywords: electrification, off-road vehicles, lithium battery, battery module, LiFePO
4
, battery management system
1 Introduction
Among means of transportation, a large portion is
occupied by off-road vehicles used in a variety of
commercial and industrial applications. These
vehicles include mobile work machines for
various applications, such as building sites, earth
moving, street cleaning, as well as agriculture,
horticulture, greenhouse, and gardening. A diesel
engine commonly powers off-road vehicles. The
replacement or the combination of the internal
combustion engine with an electric motor might
be a remarkable step toward energy sustainability
by reducing CO
2
emissions and by improving
energy utilization efficiency [1] [2] [3].
A recent study made by ENEA on the Italian
market for mobile work machines gives a good
idea of the relevance of these kinds of vehicles
and the impact of their electrification [4]. It shows
the surprising conclusion that at 2020 the battery
market for electric mobile work machines could
be 25 % of the batteries used in electric cars. Two
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EVS27 International Battery, Hybrid and Fuel Cell Electric Vehicle Symposium
2
capacity levels, 120 Ah and 180 Ah, and three
voltages, 48 V, 96 V, and 192 V, are sufficient for
the electrification of the different families of
mobile work machines, as shown in Fig.1.
Figure 1: Power and energy required for the
electrification of off-road vehicles
The main problems that slow down the large
diffusion of the electric vehicles are the high
initial costs, mainly due to the battery cost and the
short runtime. A valid solution to reduce costs is
the adoption of standard modules.
Defining the standard modules implies to
establish the type of technology and the main
electric characteristics, voltage and capacity.
About the type of technology, the LiFePO
4
was
chosen as cathode chemistry because of safety
and costs [4]. Adopting 12 V as nominal voltage
of the module and three values of capacity, 30 Ah,
60 Ah, and 90÷100 Ah, it is possible to realize
standard modules (module 12 V 30 Ah, little
size; module 12 V - 60 Ah, medium size; module
12 V - 90÷100 Ah, large size) which can be used,
individually or series/parallel connected, to satisfy
all the applications above-mentioned [4]. On the
other hand, 12 V is the standard voltage for
starting batteries and the LiFePO
4
chemistry was
proved to be the best solution for the application
as starting lighting ignition batteries [5]. This is
due to the compatibility with the working voltages
of the electric suppliers commonly used in the
vehicles, the big current capacity (the so called
cold cranking amperes”, CCA), the particular
conditions of the working environment (high
temperature and vibrations). The series
connection of four LiFePO
4
cells equals the
working voltages of the lead battery currently
used as starting lighting ignition batteries on
board the vehicles. This is not possible with other
lithium batteries. Thus, the defined standard
module can also be used as starting lighting
ignition battery instead of the equivalent lead
battery and this is another important factor of
standardization. The standard modules were
realized by four cells LiFePO
4
series connected.
The main characteristics of the cells used in the
standard modules are shown in Table 1, 2 and 3.
Table 1: Main characteristics of the cell for the little
size module
Param
Value
Voltage [V]
3.2
Nominal capacity [Ah]
30
Dimensions (L x W x H) [mm]
103x58x168
Weight [kg]
1.15
Energy [Wh]
96
Energy density [Wh/dm
3
]
95
Specific energy [Wh/kg]
83
Working temperature (discharge)
-20 ÷ +65°C
Working temperature (charge)
0 ÷ +45°C
Discharge @
+23°C
Max continuous
current [A]
90
Peak current @
60 sec [A]
150
Cut-off voltage
[V]
2.5
Charge @
+23°C
Charge method
CC/CV
(3.65V)
Max charge
current [A]
30
Cut-off voltage
[V]
3.85
Table 2: Main characteristics of the cell for the medium
size module
Param
Value
Voltage [V]
3.2
Nominal capacity [Ah]
60
Dimensions (L x W x H) [mm]
114x61x203
Weight [kg]
2.04
Energy [Wh]
192
Energy density [Wh/dm
3
]
136
Specific energy [Wh/kg]
94
Working temperature (discharge)
-20 ÷ +65°C
Working temperature (charge)
0 ÷ +45°C
Discharge @
+23°C
Max continuous
current [A]
180
Peak current @
60 sec [A]
300
Cut-off voltage
[V]
2.5
Charge @
+23°C
Charge method
CC/CV
(3.65V)
Max charge
current [A]
60
Cut-off voltage
[V]
3.85
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EVS27 International Battery, Hybrid and Fuel Cell Electric Vehicle Symposium
3
Table 3: Main characteristics of the cell for the large
size module
Param
Voltage [V]
Nominal capacity [Ah]
Dimensions (L x W x H) [mm]
Weight [kg]
Energy [Wh]
Energy density [Wh/dm
3
]
Specific energy [Wh/kg]
Working temperature (discharge)
Working temperature (charge)
Discharge @
+23°C
Max continuous
current [A]
Peak current @
60 sec [A]
Cut-off voltage
[V]
Charge @
+23°C
Charge method
Max charge
current [A]
Cut-off voltage
[V]
2 Electrical Battery Test
Some samples of the selected batteries were tested
under EUCAR procedures to verify the
performances and the suitability to be used in the
above mentioned applications. The testing
activities were performed at the Battery Test
Room of the “Low Environmental Impact
Vehicles Laboratory at ENEA Research Centre
“Casaccia” by means of battery testers and
climatic chambers. The following tests were
performed:
energy and capacity at different current rates
and temperatures: in particular each sample
was discharged with current rates respectively
1C, 2C, 3C at the temperatures 0 °C, +23 °C
and +40 °C;
fast charge, according to the manufacturer’s
specification about the maximum
continuative charging current rate, 1C, which
theoretically corresponds to the complete
charge in one hour;
internal resistance;
cold cranking test to evaluate the suitability of
the batteries for the application as starting
lighting ignition batteries. The test was
performed following the standard CEI EN
50342-1 “Lead batteries for starting
applications Part 1: General rules and test
methods” adapted for lithium batteries.
The test results, resumed in the following figures,
show the good behaviour of the cells and confirm
their suitability for the selected applications.
2.1 Capacity
Figure 2: Results of the capacity test
At a given temperature, the capacity is not
dependent on the current rate and at a given
current rate the dependence of the capacity on the
temperature is not so strong. The best
performances are given in the field +23 ÷ +40 °C,
while in the field of temperatures lower than +23
°C a reduction of capacity is registered, but it is
completely normal.
2.2 Fast charge
The fast charge test consisted of a charge type
CC/CV (constant current/constant voltage) @ 1C,
according to the specifications of the
manufacturer. This charge theoretically
corresponds to the complete charge of the battery
in 1 h. The voltage, current and temperature of the
sample were monitored and registered during the
test. A typical example of the test results is shown
in Fig. 3.
0
20
40
60
80
100
120
0 20 40 60
Capacity [Ah]
Temperature [°C]
Capacity test
30Ah - 1C
30Ah - 2C
30Ah - 3C
60Ah - 1C
60Ah - 2C
60Ah - 3C
100Ah - 1C
100Ah - 2C
100Ah - 3C
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EVS27 International Battery, Hybrid and Fuel Cell Electric Vehicle Symposium
4
Figure 3: Results of the fast charge test
2.3 Internal resistance
The internal resistance is an important factor
affecting heating and efficiency of the cell. The
test is made by three current pulses, separated by
little rest periods: the first and the second pulses
are at 1C current rate, the first in discharge and
the second in charge, while the third is in
discharge at the maximum current value which
can be used for 30 s, according to the
manufacturer. The sequence is shown in Fig. 4.
Figure 4: Current profile for the internal resistance test
Relating to the profile above, it is possible to
identify eight characteristic points and define the
following internal resistances:
internal resistance in discharge:
R
Ω,dch
= (V
2
V
1
)/I
1C
overall internal resistance in discharge @ 1C:
R
1C,dch
= (V
3
V
1
)/I
1C
internal resistance in charge:
R
Ω,cha
= (V
4
V
5
)/I
1C
overall internal resistance in charge @ 1C:
R
1C,cha
= (V
4
V
6
)/I
1C
overall internal resistance in discharge @
high C-rate:
R
HC,dch
= (V
8
V
7
)/I
HCE
I
HCE
is the highest current which can be used for
30 s, as for the manufacturer’s specifications.
Fig. 5 shows a typical voltage and current profile
registered during the internal resistance test and
Table 4 gives an example of the results for a cell
with capacity 100 Ah, at SOC 50 %, and I
HCE
current 500 A.
Figure 5: Voltage and current profile during the
internal resistance test
Table 4: Values of internal resistance
Param
Value (mΩ)
R
Ω,dch
1.66
R
1C,dch
2.66
R
Ω,cha
1.64
R
1C,cha
1.65
R
HC,dch
1.26
The internal resistance test gave good results and
the values obtained agree with the specification of
the manufacturer.
2.4 Cold cranking test
To qualify the standard modules as starting
batteries, it was decided to verify the starting
performance. The starting performance of lead
batteries can be tested by means of the standard
CEI EN 50342-1 “Lead batteries for starting
applications Part 1: General rules and test
methods. In contrast, there is not a standard for
lithium batteries: for this reason, it was applied
the standard CEI EN 50342-1 with some
adaptations. The standard requires to completely
charge the battery, to make a rest of 24 h, to put
the battery in a climatic chamber at the
temperature -18 °C, to make a discharge at current
Icc (starting current, usually called Cold Cranking
Ampere, specified by the manufacturer of the lead
battery) within 2 minutes after the end of the
cooling phase. After 10 s of discharge, the battery
0
20
40
60
80
100
120
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
0 2000 4000 6000
Current [A]
Temperature [°C]
Voltage [V]
Time [s]
Fast charge test
voltage
current
temperature
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EVS27 International Battery, Hybrid and Fuel Cell Electric Vehicle Symposium
5
voltage must be measured and verified that it is
not lower than the minimum voltage specified by
the manufacturer and the current must be
interrupted. After a rest of 10 s, the battery must
be discharged with a current 60% of I
cc
, until the
minimum voltage is reached. We performed the
test at -10 °C, rather than at the really limit
condition of -18 °C, because it seems to be a more
realistic situation but hard enough at the same
time. Further, the minimum voltage was set to
2.5 V, according to the specification of the
manufacturer, and the current rate was 4C (as a
comparison with a lead battery 44 Ah, whose I
cc
current is 170 A).
The typical voltage profile registered during the
test is shown in Fig. 6: the voltage is always over
the minimum value, which is reached at the end of
the discharge at 60 % of I
cc
only.
Figure 6: Typical voltage and current profile during the
cold cranking test
3 Thermal Management
The electrical characterization tests at low
temperatures showed that the cells do not need to
be heated during the operation in cold conditions,
so the thermal management system of the module
is only a cooling system.
3.1 Thermal battery characterization
A thermal analysis on single cell level was
performed to study the thermal distribution during
charge and discharge without thermal
conditioning and to evaluate if battery cooling
during operation is needed. This was realized by
the means of thermocouples and a thermo camera
320 x 240 pixel with thermal sensibility less than
0,1 °C. A “hot point”, where the highest
temperatures are registered, was identified under
the negative pole. This was a very valuable
indication, which makes it possible to place the
sensor used for the thermal monitoring in the
optimal position to identify the highest
temperature.
Figure 7: Typical results of the thermo graphic analysis
during discharge, hot point on evidence
The thermal analysis also showed that the critical
temperatures are reached only very close to the
end of discharge at the maximum current rate, so
this is the only phase where battery cooling is
really necessary. Fig. 8 shows the typical
temperature profile registered during a discharge
at 300 A followed by a rest of 3600 s and a
standard charge (CC/CV @ C/3) for the cell with
capacity 100 Ah.
Figure 8: Temperature during discharge at maximum
current rate
3.2 Cooling plant with air
An experimental test bed was realized to evaluate
the performance of battery cooling by air. The
plant is a duct equipped with two blowers at the
inlet section. The fan speed is regulated to permit
different air flows. A heater allows different
working temperatures to be set. A right angle turn
is used to create turbulence and mixing of the
-1
0
1
2
3
4
5
0 500 1000 1500 2000
Voltage [V]
Current [nC]
Time [s]
Cold cranking test
Voltage
Current
World Electric Vehicle Journal Vol. 6 - ISSN 2032-6653 - © 2013 WEVA Page
Page 0566

Citations
More filters

Proceedings ArticleDOI
Yuanzheng Han1, Mike Ranjram1, Peter W. Lehn1Institutions (1)
12 Jul 2015-
Abstract: Practical challenges in distributed generation and electric vehicles have motivated the rapid development of bidirectional multi-port dc-dc converters. This paper proposes a converter that not only can perform fast battery voltage balancing and limit ground leakage current, it also features low switching ripple and component count, providing significant cost savings from reduced filter requirements and improved efficiency. Experimental testing of a 3.3 kW prototype confirms the bidirectional power transfer capability and demonstrates above 99% converter efficiency over a wide range of input power.

8 citations


Cites background from "Development and realization of lith..."

  • ...For example, standard battery packs can be found with 12 V, 48 V, 96 V or 192 V [19]....

    [...]


Journal ArticleDOI
Abstract: Engine start-stop systems have been widely adopted for internal combustion engine passenger vehicles, with low voltage 12 V systems currently capturing most of the market. While absorbed glass mat (AGM) lead-acid batteries are commonly used for this application, there is interest in other battery types to reduce cost or improve performance. This work examines a range of battery types and compares experimentally determined performance and aging characteristics. Six different start/stop batteries are tested, including two AGM, an enhanced flooded lead acid (EFB), lead carbon (PbC), nickel zinc (NiZn), and LiFePO4 battery. The batteries are aged with a series of start-stop microcycles, which consist of an accessory power and engine-starting discharge pulse followed by a charging pulse. Thirty thousand microcycles correlate with the conditions a start-stop battery would be exposed to over approximately 160,000 km of driving in a typical North American application. The testing procedure begins with two characterization tests - a capacity and HPPC charge and discharge resistance test - and is followed by 3,000 microcycles to age the battery. Characterization and aging tests are repeated until the battery is no longer able to perform the microcycles, and substantially different aging and performance characteristics are observed for each battery.

7 citations


Proceedings ArticleDOI
R. Di Rienzo1, Federico Baronti1, F. Vellucci2, Fabio Cignini3  +4 moreInstitutions (3)
01 Nov 2016-
TL;DR: The lead-acid battery of an electric minibus has been replaced with a smaller size lithium-ion battery system consisting of standard 12 V modules and a hierarchical battery management system and experiments show that fast charging of 8 min guarantees up to 1 h of operation.
Abstract: The lead-acid battery of an electric minibus has been replaced with a smaller size lithium-ion battery system consisting of standard 12 V modules and a hierarchical battery management system. The minibus has experimentally been tested to show that the reduced battery capacity, which also cuts costs, does not affect the daily operational mission. This is assuming that the driving phases are alternated with fast charging periods. Experiments show that fast charging of 8 min guarantees up to 1 h of operation.

5 citations


Cites background or methods from "Development and realization of lith..."

  • ...A first implementation of the standard module has been described in [9], [10]....

    [...]

  • ...The module current is numerically integrated by the microcontroller as part of the State-of-Charge (SoC) estimation algorithm [9], which is based on the Coulomb Counting method combined with Open Circuit Voltage (OCV) compensation [13]....

    [...]

  • ...Compared to a previous implementation of the battery module [9], [10], particular care has been given to the mechanical assembly and the thermal management to ensure good reliability....

    [...]

  • ...Therefore, the nominal voltage of the new battery must be 72V, a value achieved by 6 standard 12V battery modules [9], [10] connected in series....

    [...]


Proceedings ArticleDOI
01 Sep 2014-
Abstract: This paper describes the research effort jointly carried out by the University of Pisa and ENEA on electrochemical energy storage systems based on Lithium-ion batteries, particularly the Lithium-Iron-Phosphate cells. In more detail, the paper first illustrates the design and experimental characterization of a family of 12 V modules, each of them provided with an electronic management system, to be used for electric traction. Then, the sizing of the energy storage system for an electric bus providing a service with “fast and frequent” charge phases is described.

5 citations


Additional excerpts

  • ...Three different modules have been realized [10]....

    [...]


Proceedings ArticleDOI
Ran Gu1, Pawel Malysz1, Deqiang Wang1, Weizhong Wang1  +2 moreInstitutions (1)
27 Jun 2016-
Abstract: A pack design methodology is proposed to meet USABC PHEV-40 performance targets using battery and ultracapacitor energy storage elements in direct coupled topologies. Simulated responses of temperature dependent power capability and cold cranking requirements are embedded in the hybrid pack analysis and design process. A case study based on an 18650 NMC Lithium-ion battery cell and a non-aqueous symmetric ultracapacitor is presented to investigate replacement tradeoffs between the two energy storage components. Among the performance metrics in the case study, ultracapacitors give the greatest improvement for short term two second power. However, the 10-second discharge power requirement is shown to be a limiting design factor to which the replacement of battery cells with ultracapacitors is less effective.

3 citations


Cites methods from "Development and realization of lith..."

  • ...Although there are other characterization procedures available such as dynamic stress test [4], [5], hybrid pulse power characterization [6], and others [8,10], the MEP test performs the test by operating at the extreme current and voltage limits....

    [...]


References
More filters

Journal ArticleDOI
Marco Giuntoli1, Davide Poli1Institutions (1)
TL;DR: A new algorithm to optimize the day-ahead thermal and electrical scheduling of a large scale VPP (LSVPP) which contains: a) many small-scale producers and consumers distributed over a large territory and b) energy storage and cogeneration processes.
Abstract: Smart grids are often analyzed using a top-down approach, i.e., starting from communication and control technologies evolution, to then focus on their effects on active and passive users, in terms of new services, higher efficiency and quality of supply. However, with their bottom-up approach, virtual power plants (VPP) are very promising instruments for promoting an effective integration of distributed generation (DG) and energy storage devices as well as valid means for enabling consumers to respond to load management signals, when operated under the supervision of a scheduling coordinator. These aggregation factors can be very profitable for the distributed energy resources (DERs) economy and for the energy network itself. This paper presents a new algorithm to optimize the day-ahead thermal and electrical scheduling of a large scale VPP (LSVPP) which contains: a) many small-scale producers and consumers (“prosumers”) distributed over a large territory and b) energy storage and cogeneration processes. The algorithm also takes into account the actual location of each DER in the public network and their specific capability. Thermal and electrical generator models, load and storage devices are very detailed and flexible, as are the rates and incentives framework. Several novelties, with respect to the previous literature, are proposed. Case study results are also described and discussed.

206 citations


"Development and realization of lith..." refers background in this paper

  • ...The replacement or the combination of the internal combustion engine with an electric motor might be a remarkable step toward energy sustainability by reducing CO2 emissions and by improving energy utilization efficiency [1] [2] [3]....

    [...]


Proceedings ArticleDOI
12 Nov 2012-
Abstract: In the last years the European Union has actively promoted the renewable energies and the Combined Heat and Power (CHP) also for residential and tertiary buildings. The exploitation of renewable sources and cogeneration seems hampered by the regulatory wall that prohibit for residential, tertiary and commercial buildings the constitution of users clusters. In fact, the unification up to a threshold value of some tens of kVA, at least, can facilitate the installation of renewable energy power plants as solar PV modules or CHP systems (cogeneration) or CCHP systems (tri-generation), overcoming technical and economical barriers and combining several load profiles. The actual distribution system for low voltage LV customers appears inadequate to comply with these goals. At this aim the authors propose the design of a Sustainable Energy Microsystem (SEM) for the integration of different subsystems, currently independent, as final users and high efficiency buildings, dispersed generation from renewable and Combined Heat and Power (CHP) units and subsystems for the urban mobility: metro-transit, trams and recharging of plug-in hybrid and electric vehicles (PHEV) for the surface mobility. The integration is analyzed in the direction of a “smart city” concept, with the optimized and integrated management of many services. These activities are about the general topic of design and construction of nearly zero energy buildings with the use of innovative technologies as home and building automation. The buildings integrated in “energy hub” with dispersed generation and urban mobility systems, constitute the “energy islands” of the future smart grid.

84 citations


"Development and realization of lith..." refers background in this paper

  • ...The replacement or the combination of the internal combustion engine with an electric motor might be a remarkable step toward energy sustainability by reducing CO2 emissions and by improving energy utilization efficiency [1] [2] [3]....

    [...]


Proceedings ArticleDOI
Federico Baronti1, G. Fantechi1, Roberto Roncella1, Roberto Saletti1  +2 moreInstitutions (2)
28 May 2013-
TL;DR: The design and some preliminary experimental results of the module management unit contains a high current active equalizer that enables the dynamic charge equalization among cells and maximizes the usable capacity of the battery.
Abstract: This paper describes the design of a modular battery management system for electric off-road vehicles, where lithiumion batteries are expected to be widely used. A massive electrification of off-road vehicles can be enabled by the availability of a standard battery module, provided with an effective management unit. The design and some preliminary experimental results of the module management unit are discussed in this paper. The unit contains a high current active equalizer that enables the dynamic charge equalization among cells and maximizes the usable capacity of the battery.

17 citations


"Development and realization of lith..." refers background or methods in this paper

  • ...A proper battery management system (BMS) with active balancing was developed by the University of Pisa in cooperation with ENEA [3], [6], [7]....

    [...]

  • ...The replacement or the combination of the internal combustion engine with an electric motor might be a remarkable step toward energy sustainability by reducing CO2 emissions and by improving energy utilization efficiency [1] [2] [3]....

    [...]

  • ...EVS27 International Battery, Hybrid and Fuel Cell Electric Vehicle Symposium 1 The paper describes the development and realization of standard battery modules 12 V, made by LiFePO4 cells selected in a previous study by ENEA and the University of Pisa....

    [...]

  • ...The testing activities were performed at the Battery Test Room of the “Low Environmental Impact Vehicles Laboratory” at ENEA Research Centre “Casaccia” by means of battery testers and climatic chambers....

    [...]

  • ...A recent study made by ENEA on the Italian market for mobile work machines gives a good idea of the relevance of these kinds of vehicles and the impact of their electrification [4]....

    [...]


01 Sep 2012-
Abstract: La presente relazione documenta le attivita svolte nell'ambito della seconda parte dell’accordo di collaborazione ENEA-DII relative al perfezionamento, alla prima realizzazione come pre-serie, e al supporto all'integrazione meccanica del sistema elettronico di monitoraggio e gestione di un modulo composto da 4 celle al litio (LiFePO4) di diversa taglia (30, 60 e 100 Ah), con diverse funzioni (avviamento o trazione), componibile a sua volta per la realizzazione di batterie fino a 4 moduli In particolare, viene considerata l'attivita di supporto alle aziende incaricate delle progettazione elettronica e meccanica, finalizzata alla realizzazione dei diversi moduli dimostratori Viene usato come punto di partenza il sistema di BMS con funzioni di bilanciamento attivo, sviluppato in forma prototipale nella prima parte della ricerca e verificato dalla successiva sperimentazione Sono descritte le migliorie e le modifiche apportate ai vari livelli del progetto, hardware, firmware e software, in modo da soddisfare tutti i requisiti delle diverse applicazioni e inserire le funzionalita indicate dal coordinamento del progetto durante le prove di validazione Fa parte della presente relazione anche un sintetico manuale di istallazione e uso dei moduli realizzati, utile alla corretta applicazione delle schede da parte dell'integratore di sistema che realizza i moduli e li intende usare nelle diverse applicazioni

1 citations


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