U.S. patent application number 12/338054 was filed with the patent office on 2010-06-24 for cranking capability estimation for a vehicular starting system.
This patent application is currently assigned to GM GLOBAL TECHNOLOGY OPERATIONS, INC.. Invention is credited to Nick S. Kapsokavathis, Mutasim A. Salman, David W. Walters, Zhenhui Yao.
Application Number | 20100154524 12/338054 |
Document ID | / |
Family ID | 42264144 |
Filed Date | 2010-06-24 |
United States Patent
Application |
20100154524 |
Kind Code |
A1 |
Salman; Mutasim A. ; et
al. |
June 24, 2010 |
CRANKING CAPABILITY ESTIMATION FOR A VEHICULAR STARTING SYSTEM
Abstract
A method is provided for determining a cranking capability of a
starting system for an internal combustion engine. An average power
output of a battery is determined for the starting system during a
start engine cranking interval. A temperature of the starting
system is determined at an initiation of the start engine cranking
interval. A predetermined average power output capability for a
battery having a full state of charge at the determined temperature
is looked up. A predetermined minimum average power output required
of the battery for starting the respective engine at the determined
temperature is looked up. A state of function based on the
determined average power outputs is determined. The cranking
capability of the starting system is identified in response to the
determined state of function.
Inventors: |
Salman; Mutasim A.;
(Rochester Hills, MI) ; Yao; Zhenhui; (Warren,
MI) ; Kapsokavathis; Nick S.; (Shelby Township,
MI) ; Walters; David W.; (Sterling Heights,
MI) |
Correspondence
Address: |
MacMillan, Sobanski & Todd, LLC;One Maritime Plaza
720 Water Street, 5th Floor
Toledo
OH
43604
US
|
Assignee: |
GM GLOBAL TECHNOLOGY OPERATIONS,
INC.
Detroit
MI
|
Family ID: |
42264144 |
Appl. No.: |
12/338054 |
Filed: |
December 18, 2008 |
Current U.S.
Class: |
73/114.59 |
Current CPC
Class: |
F02N 2200/045 20130101;
F02N 2200/023 20130101; F02N 2200/046 20130101; F02N 2200/062
20130101; F02N 2200/063 20130101; F02N 11/10 20130101; F02N 11/0862
20130101; F02N 2200/064 20130101; F02N 11/0859 20130101 |
Class at
Publication: |
73/114.59 |
International
Class: |
G01M 15/04 20060101
G01M015/04 |
Claims
1. A method of determining a cranking capability of a starting
system for an internal combustion engine, the method comprising the
steps of: (a) determining an average power output of a battery for
the starting system during a start engine cranking interval; (b)
determining a temperature of the starting system at an initiation
of the start engine cranking interval; (c) looking up a
predetermined average power output capability for a battery having
a full state of charge at the determined temperature; (d) looking
up a predetermined minimum average power output required of the
battery for starting the respective engine at the determined
temperature; (e) determining a state of function based on the
average power output of steps (a), (c), and (d); and (f)
identifying the cranking capability of the starting system in
response to the determined state of function.
2. The method of claim 1 wherein step (e) further comprises the
steps of: determining a difference between the average power
outputs determined in steps (a) and (d); determining a difference
between the average power outputs determined in steps (c) and (d);
and calculating a ratio between the determined differences.
3. The method of claim 1 further comprising the step of determining
if a starter motor deficiency is present, wherein the state of
function is identified as a state of function for the starting
system if a starter motor deficiency is present.
4. The method of claim 3 wherein the state of function is
identified as a state of function for the battery if no starter
motor deficiency is present.
5. The method of claim 1 wherein the step of identifying the
cranking capability includes actuating an indicator to a driver of
the vehicle for identifying a weakened starting system.
6. A method of determining a cranking capability of a starting
system, the method comprising the steps of: (a) detecting an
ignition start operation; (b) determining a temperature of the
starting system at the initiation of the ignition start; (c)
measuring a battery voltage and a current during a predetermined
interval of the ignition start; (d) determining an actual average
power output value of the battery during the predetermined
interval; (e) determining an average power output capability for a
battery having a full state of charge at the determined
temperature; (f) determining a minimum average power output value
required of the battery for starting the respective engine at the
determined temperature; and (g) calculating a state of function
value of the starting system as a function of the average power
output values determined in steps (d), (e), and (f).
7. The method of claim 6 wherein the step of identifying the
cranking capability of the starting system further comprises
comparing the calculated state of function value determined in step
(g) to a state of function threshold value and actuating a warning
signal to a driver of the vehicle for identifying a weakened
starting system in response to the determined state of function
value being less than the state of function threshold value.
8. The method of claim 6 further comprising the steps of:
determining whether a cranking device for cranking the engine is
deteriorated; identifying the determined state of function value as
a starting system state of function value in response to a
determination that the cranking device is deteriorated, otherwise,
outputting the state of function value as a battery state of
function value.
9. The method of claim 6 wherein the state of function is
represented by the following formula: SOF = P _ b - P _ b_li m P _
b_new - P _ b_li m .times. 100 % ##EQU00011## where P.sub.b is the
average power output of the battery of the starting system,
P.sub.b.sub.--.sub.new is the average power output of a battery
having a full state of charge, and P.sub.b.sub.--.sub.lim is the
minimum average power output required by the battery to crank the
vehicle engine at the determined temperature.
10. The method of claim 6 wherein the minimum average power output
value required of the battery is determined as a function of the
efficiency of the starting system, the load drawn by the starting
system, and the kinetic power output of the starting system.
11. The method of claim 6 wherein step (b) includes measuring the
temperature of the battery.
12. The method of claim 6 wherein step (b) includes measuring the
temperature of the starter motor.
13. The method of claim 6 wherein step (b) includes measuring the
temperature of the engine.
14. The method of claim 6 wherein step (b) includes measuring the
temperature of at least one of the battery, the starter motor, and
the engine.
15. A starting performance indication system for a vehicle starting
system, the vehicle starting system including an internal
combustion engine, a cranking device for cranking the internal
combustion engine, a coupling device for mechanically coupling the
cranking device to the internal combustion engine, and an energy
storage device for supplying power to the cranking device for
energizing the cranking device, the starting performance indication
system comprising: at least one sensing device for determining a
temperature of at least the energy storage device, the cranking
device, and engine oil in the engine; a voltage sensing device for
sensing the voltage output from the energy storage device; a
current sensing device for sensing the current drawn by the
cranking device; a control module having a starting system
monitoring and prognosis routine for determining a state of
function of the starting system, wherein the control module
determines an average power output of the battery during the
predetermined interval during engine cranking, an average power
output for a battery having a full state of charge for starting the
internal combustion engine at the determined temperature, and a
minimum average power output value required of the battery for
starting the internal combustion engine at the determined
temperature; wherein the control module estimates the cranking
capability of the starting system as function of the average power
output of the battery during the predetermined interval during
engine cranking, as a function of the average power output for a
battery having a full state of charge, and as a function of the
minimum average power output value required of the battery for
starting the internal combustion engine.
16. The starting performance indication system of claim 15 further
comprising a warning indicator for providing a cranking capability
warning to the driver of the vehicle in response to the control
module determining the state of function being a weakened
state.
17. The starting performance indication system of claim 15 wherein
the control module estimates the cranking capability of the
starting system by comparing a calculated state of function to a
state of function threshold value, the calculated state of function
value being determined by the following formula: SOF = P _ b - P _
b_li m P _ b_new - P _ b_li m .times. 100 % ##EQU00012## where
P.sub.b is the average power output of the battery over a
predetermined time interval, P.sub.b.sub.--.sub.new is an average
power output of a new battery have a full SOC that successfully
cranks the engine, and P.sub.b.sub.--.sub.lim is a minimum average
power output value required of the battery to successfully crank
the engine over the predetermined for the respective starting
system.
18. The starting performance indication system of claim 15 wherein
the control module includes a battery control module.
Description
BACKGROUND OF INVENTION
[0001] An embodiment relates generally to evaluating a cranking
capability of a vehicle starting system.
[0002] Vehicle batteries are used for conventional functions such
as starting, lighting, and ignition within a vehicle. The vehicle
battery must satisfy the power needs of all the electronics
associated with those functions. Many vehicle breakdowns are
related to automotive electronic and battery failures such as the
vehicle battery being in a low state of charge during vehicle
starting. The vehicle starting system includes the battery, the
starter motor, and the engine. To successfully crank the vehicle
engine, the electrical power supply provided by the battery must be
able to supply an adequate amount of power to the starter motor for
cranking the engine. The power must not only be able to
successfully initiate cranking of the starter and engine, but must
be able to overcome the frictional and resistive interactions of
the accessories coupling the starter motor and the engine.
[0003] The state of function (SOF) for a starting system is a
comprehensive reflection of a starting system's state of health
(SOH) and state of charge (SOC). The SOF provides important
information regarding the cranking capability of the starting
system. What is needed is a method for evaluating the SOF for the
starting system for determining the cranking capability of the
vehicle starting system.
SUMMARY OF INVENTION
[0004] An advantage of an embodiment is an onboard monitoring and
prognosis of the state of function of the starting system by
measuring the power output during a specific interval during the
engine cranking operation of a vehicle to determine the cranking
capability of the vehicle. Another advantage is the determination
of whether the state of function is directed to the battery or
starter motor.
[0005] An embodiment contemplates a method of determining a
cranking capability of a starting system for an internal combustion
engine: (a) an average power output of a battery for the starting
system during an start engine cranking interval is determined; (b)
a temperature of the starting system at an initiation of the start
engine cranking interval is determined; (c) a look up is performed
for a predetermined average power output capability for a battery
having a full state of charge at the determined temperature; (d) a
look up is performed for a predetermined minimum average power
output of the battery at the determined temperature; (e) a state of
function is determined based on the average power output of steps
(a), (d), and (e); and (f) the cranking capability is identified of
the starting system in response to the determined state of
function.
[0006] An embodiment contemplates a method of determining a
cranking capability of a starting system: (a) an ignition start
operation is detected; (b) a temperature of the starting system at
the initiation of the ignition start is determined; (c) a battery
voltage and a current is measured during a predetermined interval
of the ignition start; (d) an actual average power output value of
the battery during the predetermined interval is determined; (e) an
average power output capability for a battery having a full state
of charge is determined at the determined temperature; (f) a
minimum average power output value required of the battery for
starting the respective engine at the determined temperatures is
determined; (g) a state of function value of the starting system is
calculated as a function of the average power output values
determined in steps (d), (e), and (f).
[0007] An embodiment contemplates a starting performance indication
system is provided for a vehicle starting system. The vehicle
starting system includes an internal combustion engine, a cranking
device for cranking the internal combustion engine, a coupling
device for mechanically coupling the cranking device to the
internal combustion engine, and an energy storage device for
supplying power to the cranking device for energizing the cranking
device. At least one sensing device determines a temperature of at
least the energy storage device, the cranking device, and engine
oil in the engine. A voltage sensing device senses the voltage
output from the energy storage device. A current sensing device for
sensing the current drawn by the cranking device. A control module
having a starting system monitoring and prognosis routine
determines a state of function of the starting system. The control
module determines an average power output of the battery during the
predetermined interval during engine cranking, an average power
output for a battery having a full state of charge for starting the
internal combustion engine at the determined temperature, and a
minimum average power output value of the battery required for
starting the internal combustion engine at the determined
temperatures. The control module estimates the cranking capability
of the starting system as function of the average power output of
the battery during the predetermined interval during engine
cranking as a function of the average power output for a battery
having a full state of charge for starting the internal combustion
engine at the determined temperature, and as a function of the
minimum average power output value of the battery required for
starting the internal combustion engine at the determined
temperatures.
BRIEF DESCRIPTION OF DRAWINGS
[0008] FIG. 1 is a schematic illustration of a starting system for
an internal combustion engine of a vehicle.
[0009] FIG. 2 is a graph of experimental cranking data of new
battery and an aged battery.
[0010] FIGS. 3-4 show a flowchart of a method for a state of
function estimation technique.
DETAILED DESCRIPTION
[0011] There is shown generally in FIG. 1 a vehicle starting system
10. The starting system 10 includes a battery 11 for storing an
electrical charge therein. The battery 11 provides electrical power
to a starter motor 12 for cranking an internal combustion engine 13
of a vehicle. The starter motor 12 when energized engages a ring
gear of a flywheel 14 that is coupled to the internal combustion
engine 13 for cranking the internal combustion engine 13.
[0012] The electrical charge supplied by the battery 11 to the
starter motor 12 must not only be of a sufficient charge to
successfully energize the starter motor, but must supply enough
power to overcome the torsion friction of meshing teeth between the
pinion gear of the starter motor 12 and the ring gear of the
flywheel 14, internal engine components, and air compression of the
engine cylinders. Therefore, if any deficiencies are present in the
starting system aside from the battery 11, then a state of function
(SOF) is determined for the starting system as a whole and not just
the battery 11.
[0013] A voltage sensor 15 and a current sensor 16 monitor and
record the voltage and current, respectively, over a predetermined
interval during engine cranking which is used to determine an
average power output of the battery during engine cranking. The
average power during a fixed length of time is one of the factors
used to estimate the battery SOF while starting a vehicle.
[0014] Power available by the battery during engine cranking is
affected by the temperature, the battery state of health (SOH), and
the battery state of charge (SOC) for a specific engine. In
general, the power output by the battery is higher at elevated
battery temperatures, high SOC, and high SOH. This allows for a
faster and easier engine turn over. The power output by the battery
has to be higher than a minimum threshold value in order to
successfully crank the engine. If the temperature of the engine
decreases, then the minimum power required to successfully crank
the engine increases. Therefore, a temperature sensor 17 is
provided for monitoring a temperature of the battery 11, a
temperature sensor 18 is provided for monitoring a temperature of
the starter motor 12, and a temperature sensor 19 is provided for
monitoring a temperature of the engine oil. Each of the temperature
measurements are provided to a control module 20 which includes a
starting system monitoring and prognosis routine for determining
the SOF of the starting system. The control module 20 maybe any
vehicle controller including, but not limited to, a battery control
module.
[0015] FIG. 2 illustrates a graph of average battery output power
curves obtained over a predetermined engine cranking interval. Plot
line 21 illustrates an average battery power output curve for a new
battery having a full SOC. Plot line 22 is a minimum average power
output curve that is required to successfully crank the engine over
the predetermined starting interval for the respective starting
system. Plot line 23 illustrates the measured average power output
curve for the respective battery of the starting system during the
starting of the engine over the predetermined time interval. As
shown in FIG. 2, a difference 24 between the plot line 22 for the
minimum average power output curve and the plot line 21 for the new
battery having a full SOC value at a respective temperature is
compared to the difference 25 between the plot line 22 for the
minimum average power output curve and the plot line 23 for the
average power output of the respective battery of the starting
system at the same respective temperature. The ratio of the
absolute value of the difference 24 to the absolute value of the
difference 25 is defined to be the percentage SOF. An equation for
determining the SOF is as follows:
SOF = P _ b - P _ b_li m P _ b_new - P _ b_li m .times. 100 % ( 1 )
##EQU00001##
where P.sub.b is the average power output of the battery over a
predetermined time interval, P.sub.b.sub.--.sub.new is an average
power output of a new battery have a full SOC that successfully
cranks the engine, and P.sub.b.sub.--.sub.lim is a minimum average
power output required from the battery to successfully crank the
engine over the predetermined time interval for the respective
starting system.
[0016] The SOF equation compares the ratio of the average power
output of the current battery and a new battery having a full SOC
to a minimum average power output value to establish a SOF value.
The power output for a new battery having a full SOC (
P.sub.b.sub.--.sub.new) is provided in a look up table previously
measured by experimentation. The minimum average power output (
P.sub.b.sub.--.sub.lim) is a function of the efficiency of the
starter motor and the engine load and is determined through
experimentation.
[0017] FIGS. 3 and 4 illustrate a flowchart for a SOF estimation
technique. The estimation technique illustrates a method for
determining the SOF, shown in equation (1), by determining various
power loads required to successfully crank the engine. The
following method illustrates the estimation techniques for deriving
the SOF of the battery/starting system.
[0018] In step 30, the ignition key is turned to the on position to
initiate cranking of the engine by the starter motor. In step 31,
the temperature of the engine oil, battery, and starter motor are
determined at the initiation of the engine cranking operation. It
should be understood that step of determining the temperatures of
the each of the devices may be performed by direct
sensing/measuring the temperature of the devices, estimating the
temperature of the devices, or may be determined indirectly from
the measurements or estimates of other sensed devices within the
vehicle.
[0019] In step 32, the output voltage V.sub.b and the output
current I.sub.b of the battery is measured and recorded over a
predetermined interval from the initiation of the starting engine
sequence (e.g. 0-0.5 sec).
[0020] In step 33, a determination is made whether the engine is
successfully cranked. If the determination is made that the engine
is not successfully cranked, then the routine proceeds to step 46
where the routine terminates since the inability of the engine to
crank implies the SOF is zero. If the determination is made that
the engine is successfully cranked, then in step 34, an average
power P.sub.b is determined by the following equation:
P _ b = i = 0 i = n V b ( i ) I b ( i ) .DELTA. t n .DELTA. t = i =
0 i = n V b ( i ) I b ( i ) n . ( 2 ) ##EQU00002##
[0021] In step 35, a minimum average power output value
P.sub.b.sub.--.sub.lim and an average power output for a battery
having a full state of charge P.sub.b.sub.--.sub.new are
determined. The minimum average power output value
P.sub.b.sub.--.sub.lim is the minimum power required by the battery
to successfully crank the engine at the initiation of the cranking
sequence. P.sub.b.sub.--.sub.new is the average power output by a
new battery when successfully cranking the respective engine.
P.sub.b.sub.--.sub.lim and P.sub.b.sub.--.sub.new are determined by
a lookup table based on the respective temperatures determined in
step 31.
[0022] In step 36, parameter estimation is performed for
determining the P.sub.load and starter efficiency .eta..sub.s
during the time interval of cranking the engine. P.sub.load is the
power consumed by the load devices including of the starting system
when cranking the engine. Such devices include the starter motor,
engine, and other frictional and resistive interactions between the
starter motor and the engine including air pressure combustion in
the engine. To perform parameter estimation for P.sub.load and
.eta..sub.s, the dynamics of the starting system must be taken into
consideration. The system equation of the dynamics for the starting
system is represented by the following formula:
( J e r 2 + J s ) .omega. . s = ( T s - T sf ) - 1 r ( T fe + T c )
( 3 ) ##EQU00003##
where J.sub.e is the inertia of the engine, J.sub.s is the inertia
of the starter motor, r is the gear ratio from the starter motor to
the engine flywheel, .omega..sub.s is the starter motor rotation
speed, T.sub.s is the induced starter motor torque, T.sub.sf is the
starter motor friction torque, T.sub.fe is the engine friction
torque, and T.sub.c is the torque introduced by the cylinder
compressed air pressure.
[0023] The equivalent inertia of the engine and the starter motor
as viewed at the starter motor side is represented by the following
equation:
J eff = J e r 2 + J s ( 4 ) ##EQU00004##
therefore, the total load that must be overcome by the starter
motor during cranking is represented by the equation:
T load = T sf + T fe + T c r . ( 5 ) ##EQU00005##
As a result, the system equation can be re-written as follows:
J.sub.eff{dot over (.omega.)}.sub.s=T.sub.s-T.sub.load. (6)
The system equation can be further re-written by multiplying
equation (6) by the rotational speed .omega..sub.s which produces
the following equation:
J.sub.eff.omega..sub.s{dot over
(.omega.)}.sub.s=T.sub.s.omega..sub.s-T.sub.load.omega..sub.s
(7)
where T.sub.s.omega..sub.s is the generated mechanical power by the
starter motor.
[0024] The supplied electrical power is represented by the formula
as follows:
P.sub.b=I.sub.bV.sub.b. (8)
[0025] Therefore, if the average energy conversion efficiency
.eta..sub.s of the starter motor in a normal condition is assumed
constant and is represented by:
T.sub.s.omega..sub.s=.eta..sub.sP.sub.b=.eta..sub.sI.sub.bV.sub.b
(9)
then
J.sub.eff.omega..sub.s{dot over
(.omega.)}.sub.s=.eta..sub.sI.sub.bV.sub.b-P.sub.load (10)
where P.sub.load=T.sub.load .omega..sub.s is the power consumed by
the load. The discrete form of Eq. 10 is approximated by the
equation:
J eff .omega. s ( n ) ( .omega. s ( n ) - .omega. s ( n - 1 ) ) dt
= .eta. s I b ( n ) V b ( n ) - P load . ( 11 ) ##EQU00006##
[0026] To estimate the parameters P.sub.load and .eta..sub.s the
following assumptions are made:
y ( n ) = J eff .omega. s ( n ) ( .omega. s ( n ) - .omega. s ( n -
1 ) ) dt ( 12 ) x ( n ) = I b ( n ) V b ( n ) ( 13 ) a = .eta. s (
14 ) b = - P load ( 15 ) ##EQU00007##
then equation 11 is as follows:
y(n)=ax(n)+b (16)
where .omega..sub.s is r times of engine speed .omega..sub.e, and
.omega..sub.e, I.sub.b and V.sub.b are measured signals.
[0027] Therefore y(n) and x(n) are known data sequences and
equation (16) is a linear form for determining parameters a and b.
Using this parameter estimation technique, the parameters a and b
(i.e., .eta..sub.s and P.sub.load) can be estimated.
[0028] Once the efficiency .eta..sub.s and average power load value
P.sub.load is estimated, the kinetic power of the system may be
determined using the following equation:
P.sub.e=J.sub.eff.omega..sub.s{dot over (.omega.)}.sub.s (17)
P.sub.e=.eta..sub.sP.sub.b-P.sub.load (18)
therefore, over a fixed interval, the average kinetic power is as
follows:
P.sub.e=.eta..sub.s P.sub.b- P.sub.load. (19)
[0029] It is assumed that the average kinetic power P.sub.e has to
be higher than an average kinetic power limit value
P.sub.e.sub.--.sub.lim to successfully crank the engine which is
dependent on a constant engine temperature. For a new engine and a
new starter motor, the nominal value of average efficiency
.eta..sub.s and average power load P.sub.load.sub.--.sub.nom are
constant at a respective temperature. Therefore, the minimum
average power supplied from the battery required to successfully
crank the engine is determined by the following formula:
P _ b_lim _no m = P _ e_lim + P _ load_nom .eta. s_nom . ( 20 )
##EQU00008##
[0030] If a deficiency is present in the starting system as a
result of the engine or starter motor, then the average efficiency
.eta..sub.s and average power load P.sub.load could change
significantly from the nominal values, and under such
circumstances, the minimum power supplied to the starter motor from
the battery has to adjust to satisfy the minimum requirement of
P.sub.e.
[0031] In step 37, the nominal values for efficiency
.eta..sub.s.sub.--.sub.nom and average power load
P.sub.load.sub.--.sub.nom are compared to the estimated values for
the average efficiency .eta..sub.s.sub.--.sub.est and average power
load P.sub.load.sub.--.sub.est, respectively. In step 38, a
determination is made whether the absolute value of the difference
between the estimated average efficiency .eta..sub.s.sub.--.sub.est
and the nominal average efficiency .eta..sub.s.sub.--.sub.nom is
greater than a predetermined efficiency threshold .sigma..sub.1,
and whether an absolute value of the difference between the nominal
average power load P.sub.load.sub.--.sub.nom and the estimated
average power load P.sub.load.sub.--.sub.est is greater than a
predetermined power load threshold .sigma..sub.2. The comparison is
represented by the formulas shown below:
|.eta..sub.s.sub.--.sub.nom-.eta..sub.s.sub.--.sub.est|>=.sigma..sub.-
1, or (21)
| P.sub.load.sub.--.sub.nom-
P.sub.load.sub.--.sub.est|>=.sigma..sub.2. (22)
[0032] If the determination made in step 38 is that neither
condition is greater than their comparative predetermined
thresholds, then the assumption is that there is no significant
change in the nominal values of the starter motor or the engine.
The routine proceeds to step 39 where the minimum average power
required by the battery is determined based on the following
formula:
P.sub.b.sub.--.sub.lim= P.sub.b.sub.--.sub.lim.sub.--.sub.nom.
(23)
[0033] If the determination is made in step 38 that the one of the
respective conditions is greater than their comparative
predetermined thresholds, then the routine proceeds to step 40
where the minimum average power required from the battery is
derived from the following equation:
P _ e_lim = .eta. s_nom P _ b_lim _nom - P _ load_nom ( 24 ) P _
e_lim = .eta. s_est P _ b_lim - P _ load_est where ( 25 ) P _ b_lim
= .eta. s_nom P _ b_lim _nom + ( P _ load_est - P _ load_nom )
.eta. s_est . ( 26 ) ##EQU00009##
[0034] In step 41, the SOF is determined as a function of the
minimum average power required by the battery determined in steps
39 or 40. The values obtained for average values of P.sub.b,
P.sub.b.sub.--.sub.lim, and P.sub.b.sub.--.sub.new are inserted
into eq. (1) as follows:
SOF = P _ b - P _ b_li m P _ b_new - P _ b_li m .times. 100 % ( 1 )
##EQU00010##
[0035] In step 42, state of health (SOH) analysis is performed on
the starter motor. The SOH analysis determines whether any
deficiencies exist with the starter motor. This assists in
identifying whether the SOF should be identified as a starting
system SOF or a battery SOF. A starter motor SOH module may be
determined by any method can ascertain the SOH of the starter
motor.
[0036] In step 43, a determination is made whether the starter
motor deterioration is present. If starter motor deterioration is
not found to be present, then the SOF is identified as a starter
battery SOF in step 44. If starter motor deterioration is
determined to be present in step 43, then the SOF is identified as
a starter system SOF in step 45.
[0037] The SOF value determined in step 43 may be compared to a SOF
threshold value for determining whether to actuate a warning to the
driver of the vehicle identifying the cranking capability of the
starting system. The warning can be any indicator (e.g. visual,
audible, or haptic) for alerting the driver of a weakened starting
system. The SOF threshold value may be different between vehicle
models given the various sizes of the battery and the engine.
Furthermore, the SOF threshold value may be different depending on
the determination of whether the SOF relates to a starter system
SOF or a battery SOF. In step 46, the routine terminates.
[0038] While certain embodiments of the present invention have been
described in detail, those familiar with the art to which this
invention relates will recognize various alternative designs and
embodiments for practicing the invention as defined by the
following claims.
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