Electronic Vehicle Battery Problems

ELECTRONIC VEHICLE BATTERY PROBLEMS
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Contents
CHAPTER ONE: BATTERY PACK...................................................................................3
Introduction............................................................................................................. 3
Components of battery pack high voltage systems................................................4
Contactors............................................................................................................ 4
Pre-charge circuit................................................................................................. 4
Fuse..................................................................................................................... 5
Manual service disconnect (MSD)........................................................................5
Factors that affect battery pack life........................................................................5
Overcharging at high temperatures.....................................................................6
High voltage......................................................................................................... 6
Problem in using so many batteries for needed voltage.......................................10
CHAPTER 2: BATTERY MANAGEMENT SYSTEMS........................................................12
Introduction........................................................................................................... 12
Functions of Battery Management Systems..........................................................12
Current battery management systems.................................................................16
Issues with vehicle Battery management systems................................................18
Battery state evaluation..................................................................................... 18
Cell voltage measurement................................................................................. 20
Battery states estimation...................................................................................22
Battery Modeling................................................................................................ 28
Cell Balancing.................................................................................................... 28
Challenges with Battery Management Systems and Solutions..............................38
Challenges............................................................................................................. 38
Solutions............................................................................................................ 42
Life cycle assessment of battery pack in electric vehicle......................................44
CHAPTER 3: BATTERY PACK MANAGEMENT..............................................................46
Battery pack management.................................................................................... 46
Conclusion............................................................................................................. 47
References............................................................................................................... 49

CHAPTER ONE: BATTERY PACK
Introduction
A battery pack is a given set of number of indistinguishable batteries or individual battery cells.
They might be arranged in series, parallel or even mix of both to convey ideal voltage, limit, or
even power density. The term battery pack is regularly utilized when referring to radio-controlled
diversion toys and battery electric vehicles. Parts of battery packs incorporate individual batteries
or cells as well as interconnects which give electrical conductivity between them. Battery-
powered battery packs regularly contain temperature sensor, which battery charger uses to
identify finish of charging. Interconnects are likewise found in batteries as they are part that
associates every phone; however batteries are frequently just orchestrated in arrangement strings
(Paris et al., 2018).
At point when pack contains gatherings of cells in parallel there are varying wiring setups which
think about electrical parity of circuit. Battery controllers are now and again used to keep voltage
of every individual cell beneath its most extreme incentive during charging to enable flimsier
batteries to turn out to be completely energized, bringing entire pack once more into balance.
Dynamic adjusting may likewise be performed by battery balancer gadgets which may carry
energy from solid cells to flimsier ones continuously for better balance. A well-adjusted pack
keeps going longer and conveys better execution.
For an in-line bundle, cells are chosen and stacked with patch in middle of them. The cells are
squeezed together and a present heartbeat produces heat to patch them together and to weld all
associations inside to cell (Steil, 2019).

Components of battery pack high voltage systems
The battery pack high voltage framework is intended to control power stream to and from cells
and to keep up power level inside plan envelope. such is practiced using accompanying segments
whose usefulness will be talked about beneath:
 contactor
 pre-charge circuit
 fuse
 manual service disconnect
 high/risky voltage uprightness/interlock circle (HVIL) circuit
Contactors
Contactors are electrically impelled switches that are fundamentally used to disengage battery
pack from vehicle's high voltage framework when vehicle is not being used. In any case,
contactors are like performance regulator that may be opened to separate battery pack. If some
part of vehicle has glitch and drives battery pack outside its structure envelope, then it separates
battery pack. For instance, contactors may be opened by battery management system whereas
charger failure enables charger to start cheating battery pack (Boggs et al., 2017). The auxiliary
security capacity qualifies contactors as basic wellbeing gadget in an advanced high voltage
battery pack. Their usefulness alongside working points of confinement, for example, intrudes on
current rating as well as voltage rating have to be all completely comprehended.
Pre-charge circuit
As battery pack shuts contactors and advances from separated state to associated state, there is
likelihood for transitory however enormous flows. Subsequently, change must be controlled
procedure. That control is given by pre-charge circuit. The pre-charge circuit comprises of extra
contactor and resistor that controls progression of current into high voltage vehicle transport as

capacitance on vehicle transport is energized to battery pack voltage. Without pre-charge
resistor, present low opposition batteries may supply large number of amps if abruptly associated
with low obstruction load. Such may weld contacts inside contactor, or harm outside hardware.
Ultimately, pre-charge procedure permits recognition of outside flaws, for example, outer short
out issues previously permitting full battery pack current to enter high voltage transport. In such
way, pre-charge resistor is likewise necessary safety part in battery packs.
Fuse
The breaker is another significant wellbeing gadget. The circuit is utilized to shield segments
from abundance current inclusive of current over contactor intrude on rating. Breaker
determination is not trifling and should be facilitated with other high voltage framework parts to
such extent that all important failure modes are secured by either wire or contactors (Schwarz et
al., 2016).
Manual service disconnect (MSD)
A fourth wellbeing gadget utilized inside a high voltage battery pack is known as manual service
disconnect. such gadget is technique for breaking electrical progression inside pack with end
goal of vehicle administration. The manual service disconnect is regularly touch protected,
removable fenced in area containing wire. The manual service disconnect is not intended for
expulsion while there is current moving through battery pack, contactors has to be opened before
manual service disconnect evacuation. Expulsion of manual service disconnect is valuable for
overhauling high voltage arrangement vehicle on grounds that positive and negative associations
with pack are never again electrically associated.
Factors that affect battery pack life
Most electric vehicle batteries are lithium based. At point when lithium battery is charged and
released once, it is known as cycle. Lithium battery limit corrupts as cycle number increments.

Battery cycle life is estimated in cycles, with industry standard of cycles to 80 per cent limit
frequently utilized as benchmark.
Overcharging at high temperatures
At point when lithium battery is charged, its voltage goes up gradually. At point when it arrives
at full charge, battery voltage is most elevated, and will not go up considerably more. The
maximum voltage (V) differs with lithium cell science (Burkman et al., 2016). Sciences running
from workstation batteries to power apparatuses utilizing lithium-cobalt mixes and mixes
containing manganese, nickel as well as aluminum has terminal voltages around 3.8V to 4.2V.
Lithium-titanate batteries charge to 2.85V. Lithium-iron-phosphate batteries charge to about
3.65V.
Lithium battery voltage must be kept from surpassing such voltage since it not just destroys
battery life; it may prompt battery pulverization or overheating and fire in some lithium batteries.
Battery management systems (BMS) are utilized to control charging voltage with goal maximum
charging voltage as well as temperature is never surpassed.
High voltage
High voltage additionally prompts another cut-off, called schedule life. At point when outside
issue develops, it averts progression of particles at cathodes. Lithium-particle batteries contain
anodes, conductors through which current enters or even leaves cell. In middle of terminals is
electrolyte, an answer used to lead current between cells. Conduction is accomplished through
trade of particles among anodes and through electrolyte. The synthetic association inside battery
is known as a redox response. At point when lithium-bearing electrolyte interacts with cathode, it
frames layer. The interface where trading of particles occurs between cathode and electrolyte is
known as strong electrolyte interface (SEI) and such structures SEI layer (Barillas et al., 2015).

The SEI layer adds to inward obstruction. As battery ages layer increments and inside
obstruction increments. Sooner or later, layer turns out to be huge enough that no particles may
pass and battery life closes (Boggs et al., 2016). Such sort of battery lifetime utmost is
exacerbated more extended cell is kept at greatest voltage alongside high temperature. The
thought here is to maintain strategic distance from most extreme voltage as well as high
temperatures for expanded timeframes. Battery makers know about such, and keep their batteries
at conditions of charge of as low as 40 per cent to keep up battery limit during capacity as well as
shipment.
To build cell schedule life, overvoltage and high temperatures must be avoided. Extremely high
voltage and temperature damage battery pack permanently and reduce battery life. The charge
level in batteries is depicted in two different ways. One portrayal is called state of charge. In case
cell is completely energized, it is said to be at 100 per cent state of charge. The other important
aspect which is considered is called depth of discharge. In event that cell is completely used, it is
said to be at 100 per cent discharged or depth of discharge is maximum. That implies 100 per
cent state of charge cell is equivalent to zero per cent depth of discharge. State of charge works
like fuel check (Kowalewski, 2017).
For most maximum battery cycle life, 100 per cent depth of discharge is considered bad for
battery health. Analysts have discovered that enhancements in cycle life increases non-linearly as
severity of discharge is reduced. Cycle life improves quicker when depth of discharge decreases,
so all-out charge moved is more noteworthy at lower profundity of discharge. Such finding helps
in understanding fact that battery discharge needs to be in limit and when depth of discharge
crosses that minimum barriers damage on battery cycle life is permanent. In case battery pack is
intended to have limit giving long range, all things considered, every day charging will be at low

depth of discharge. The effect of such on electric vehicle configuration is significant. It implies
that course to long range, high limit, may likewise bring about lower depth of discharge and
longer life for given battery (Linse and Kuhn, 2015). Further, if high voltage or current charging
is deliberately restricted during most activity, battery schedule life might be increased.
At long last, batteries are described by C rates. Basically, battery will be determined in amp-
hours. An amp-hour is measure of current battery may pull in 1 hour. The C rate is characterized
in units of C, where 1C implies battery may be charged in 1 hour. In case battery is charged at
2C, it implies battery might be charged in half an hour. High-C-rate batteries may be charged or
discharged very quick and produce great deal of intensity. Low-C-rate batteries have lower
control.
For lithium batteries of given science type, changes may be made to raise or lower C. The
tradeoff is higher energy limit in kWh for lower C, or power. In battery pack, more cells in
parallel lower pinnacle current in every cell and enable every cell to work at lower C rate. In
electric vehicle application, ideal pinnacle battery pack flow may be seen with either pack with
increasing parallel cells (in such way, bigger energy limit) or less parallel cells and higher C rate
(Beaston, Nystrom and Emmons, 2018). With parallel cells, low-C battery may remain inside its
C limit. The effect of such on electric vehicles is that battery pack estimated for long range may
have lower C rate and higher energy limit. Surpassing C rates brings about anode changes that
debase execution. Appropriate terminal activity relies upon cathode surface structure. That
structure is changed if C rate is surpassed.
Various advantages show up when electric vehicle battery is measured for long extend. A bigger
limit battery brings about lower normal profundity of release and subsequently longer cycle life
and lower pinnacle charge/release rate. In case greatest charge is restricted to 80 per cent under