<s>
An	O
alternator	B-Algorithm
is	O
a	B-General_Concept
type	O
of	O
electric	O
generator	O
used	O
in	O
modern	O
automobiles	O
to	O
charge	O
the	O
battery	B-Algorithm
and	O
to	O
power	O
the	O
electrical	O
system	O
when	O
its	O
engine	O
is	O
running	O
.	O
</s>
<s>
Until	O
the	O
1960s	O
,	O
automobiles	O
used	O
DC	O
dynamo	B-Language
generators	O
with	O
commutators	O
.	O
</s>
<s>
As	O
silicon-diode	O
rectifiers	B-Algorithm
became	O
widely	O
available	O
and	O
affordable	O
,	O
the	O
alternator	B-Algorithm
gradually	O
replaced	O
the	O
dynamo	B-Language
.	O
</s>
<s>
The	O
modern	O
type	O
of	O
vehicle	O
alternators	B-Algorithm
were	O
first	O
used	O
in	O
military	O
applications	O
during	O
World	O
War	O
II	O
,	O
to	O
power	O
radio	O
equipment	O
on	O
specialist	O
vehicles	O
.	O
</s>
<s>
After	O
the	O
war	O
,	O
other	O
vehicles	O
with	O
high	O
electrical	O
demands	O
—	O
such	O
as	O
ambulances	O
and	O
radio	O
taxis	O
—	O
could	O
also	O
be	O
fitted	O
with	O
optional	O
alternators	B-Algorithm
.	O
</s>
<s>
Alternators	B-Algorithm
were	O
first	O
introduced	O
as	O
standard	O
equipment	O
on	O
a	B-General_Concept
production	O
car	O
by	O
the	O
Chrysler	O
Corporation	O
on	O
the	O
Valiant	O
in	O
1960	O
,	O
several	O
years	O
ahead	O
of	O
Ford	O
and	O
General	O
Motors	O
.	O
</s>
<s>
Some	O
early	O
automobiles	O
,	O
like	O
the	O
Ford	O
Model	O
T	O
,	O
used	O
a	B-General_Concept
different	O
sort	O
of	O
charging	O
system	O
:	O
an	O
engine-driven	O
magneto	B-Algorithm
which	O
generated	O
low-voltage	O
alternating	O
current	O
that	O
was	O
supplied	O
to	O
trembler	O
coils	O
,	O
which	O
provided	O
the	O
high	O
voltage	O
needed	O
to	O
generate	O
ignition	O
sparks	O
.	O
</s>
<s>
(	O
This	O
was	O
different	O
from	O
a	B-General_Concept
true	O
ignition	B-Algorithm
magneto	I-Algorithm
,	O
which	O
generates	O
high	O
voltage	O
directly	O
.	O
)	O
</s>
<s>
Since	O
such	O
a	B-General_Concept
magneto	B-Algorithm
system	O
only	O
depended	O
on	O
the	O
engine	O
's	O
motion	O
to	O
generate	O
current	O
,	O
it	O
could	O
even	O
be	O
used	O
when	O
starting	O
a	B-General_Concept
manually	O
cranked	O
engine	O
,	O
provided	O
the	O
crank	O
was	O
pulled	O
sharply	O
,	O
so	O
that	O
the	O
magneto	B-Algorithm
would	O
produce	O
enough	O
current	O
for	O
the	O
coils	O
to	O
make	O
good	O
sparks	O
.	O
</s>
<s>
The	O
Model	O
T	O
incorporated	O
its	O
magneto	B-Algorithm
into	O
the	O
engine	O
flywheel	O
.	O
</s>
<s>
The	O
first	O
Model	O
Ts	O
used	O
the	O
magneto	B-Algorithm
solely	O
for	O
the	O
trembler	O
coil	O
ignition	O
.	O
</s>
<s>
Beginning	O
with	O
the	O
1915	O
model	O
year	O
,	O
Ford	O
added	O
electric	O
headlights	O
,	O
also	O
powered	O
by	O
the	O
magneto	B-Algorithm
.	O
</s>
<s>
The	O
magneto	B-Algorithm
circuit	O
was	O
strictly	O
AC	O
,	O
with	O
no	O
battery	B-Algorithm
included	O
.	O
</s>
<s>
(	O
There	O
was	O
a	B-General_Concept
switch	O
on	O
the	O
ignition	O
coils	O
to	O
use	O
a	B-General_Concept
battery	B-Algorithm
instead	O
,	O
which	O
could	O
be	O
helpful	O
when	O
starting	O
in	O
cold	O
weather	O
,	O
but	O
Ford	O
neither	O
provided	O
a	B-General_Concept
battery	B-Algorithm
nor	O
did	O
it	O
encourage	O
the	O
use	O
of	O
one	O
before	O
it	O
introduced	O
an	O
electric	O
starter	O
in	O
1919	O
.	O
</s>
<s>
The	O
owner	O
would	O
have	O
to	O
install	O
the	O
battery	B-Algorithm
themselves	O
and	O
charge	O
it	O
externally	O
.	O
)	O
</s>
<s>
This	O
starter	O
installation	O
also	O
included	O
a	B-General_Concept
battery	B-Algorithm
,	O
charged	O
by	O
a	B-General_Concept
conventional	O
dynamo	B-Language
,	O
and	O
the	O
lights	O
were	O
now	O
powered	O
by	O
the	O
battery	B-Algorithm
.	O
</s>
<s>
However	O
,	O
the	O
flywheel	O
magneto	B-Algorithm
still	O
powered	O
the	O
ignition	O
,	O
and	O
since	O
models	O
without	O
the	O
starter	O
had	O
no	O
battery	B-Algorithm
,	O
they	O
continued	O
to	O
use	O
magneto-powered	O
lights	O
.	O
</s>
<s>
Alternators	B-Algorithm
have	O
several	O
advantages	O
over	O
direct-current	O
generators	O
(	O
dynamos	B-Language
)	O
.	O
</s>
<s>
Alternators	B-Algorithm
are	O
:	O
</s>
<s>
A	B-General_Concept
set	O
of	O
rectifiers	B-Algorithm
(	O
diode	O
bridge	O
)	O
is	O
required	O
to	O
convert	O
AC	O
to	O
DC	O
.	O
</s>
<s>
To	O
provide	O
direct	O
current	O
with	O
low	O
ripple	O
,	O
a	B-General_Concept
polyphase	O
winding	O
is	O
used	O
and	O
the	O
pole-pieces	O
of	O
the	O
rotor	O
are	O
shaped	O
(	O
claw-pole	O
)	O
.	O
</s>
<s>
Automotive	O
alternators	B-Algorithm
are	O
usually	O
belt-driven	O
at	O
2	O
–	O
3	O
times	O
crankshaft	O
speed	O
,	O
speeds	O
that	O
could	O
cause	O
a	B-General_Concept
commutator	O
to	O
fly	O
apart	O
in	O
a	B-General_Concept
generator	O
.	O
</s>
<s>
The	O
alternator	B-Algorithm
runs	O
at	O
various	O
RPM	O
(	O
which	O
varies	O
the	O
frequency	O
)	O
since	O
it	O
is	O
driven	O
by	O
the	O
engine	O
.	O
</s>
<s>
This	O
is	O
not	O
a	B-General_Concept
problem	O
because	O
the	O
alternating	O
current	O
is	O
rectified	B-Algorithm
to	O
direct	O
current	O
.	O
</s>
<s>
Alternator	B-Algorithm
regulators	O
are	O
also	O
simpler	O
than	O
those	O
for	O
generators	O
.	O
</s>
<s>
Generator	O
regulators	O
require	O
a	B-General_Concept
cutout	O
relay	O
to	O
isolate	O
the	O
output	O
coils	O
(	O
the	O
armature	O
)	O
from	O
the	O
battery	B-Algorithm
at	O
low	O
speed	O
;	O
that	O
isolation	O
is	O
provided	O
by	O
the	O
alternator	B-Algorithm
rectifier	B-Algorithm
diodes	O
.	O
</s>
<s>
Also	O
,	O
most	O
generator	O
regulators	O
include	O
a	B-General_Concept
current	O
limiter	O
;	O
alternators	B-Algorithm
are	O
inherently	O
current-limited	O
.	O
</s>
<s>
The	O
claw	O
pole	O
design	O
produces	O
an	O
AC	O
waveform	O
that	O
is	O
more	O
efficiently	O
rectified	B-Algorithm
than	O
a	B-General_Concept
sine	O
wave	O
.	O
</s>
<s>
Despite	O
their	O
names	O
,	O
both	O
'	O
DC	O
generators	O
 '	O
(	O
or	O
'	O
dynamos	B-Language
 '	O
)	O
and	O
'	O
alternators	B-Algorithm
 '	O
initially	O
produce	O
alternating	O
current	O
.	O
</s>
<s>
In	O
a	B-General_Concept
so-called	O
'	O
DC	O
generator	O
 '	O
,	O
this	O
AC	O
current	O
is	O
generated	O
in	O
the	O
rotating	O
armature	O
,	O
and	O
then	O
converted	O
to	O
DC	O
by	O
the	O
commutator	O
and	O
brushes	O
.	O
</s>
<s>
In	O
an	O
'	O
alternator	B-Algorithm
 '	O
,	O
the	O
AC	O
current	O
is	O
generated	O
in	O
the	O
stationary	O
stator	O
,	O
and	O
then	O
is	O
converted	O
to	O
DC	O
by	O
the	O
rectifiers	B-Algorithm
(	O
diodes	O
)	O
.	O
</s>
<s>
Typical	O
passenger	O
vehicle	O
and	O
light	O
truck	O
alternators	B-Algorithm
use	O
Lundahl	O
or	O
'	O
claw-pole	O
'	O
field	O
construction	O
.	O
</s>
<s>
This	O
uses	O
a	B-General_Concept
shaped	O
iron	O
core	O
on	O
the	O
rotor	O
to	O
produce	O
a	B-General_Concept
multi-pole	O
field	O
from	O
a	B-General_Concept
single	O
coil	O
winding	O
.	O
</s>
<s>
These	O
alternators	B-Algorithm
have	O
their	O
field	O
and	O
stator	O
windings	O
cooled	O
by	O
axial	O
airflow	O
,	O
produced	O
by	O
an	O
external	O
fan	O
attached	O
to	O
the	O
drive	O
belt	O
pulley	O
.	O
</s>
<s>
Modern	O
vehicles	O
now	O
use	O
the	O
compact	O
alternator	B-Algorithm
layout	O
.	O
</s>
<s>
Better	O
cooling	O
permits	O
more	O
power	O
from	O
a	B-General_Concept
smaller	O
machine	O
.	O
</s>
<s>
The	O
stator	O
windings	O
now	O
consist	O
of	O
a	B-General_Concept
dense	O
central	O
band	O
where	O
the	O
iron	O
core	O
and	O
copper	O
windings	O
are	O
tightly	O
packed	O
,	O
and	O
end	O
bands	O
where	O
the	O
windings	O
are	O
more	O
exposed	O
for	O
better	O
heat	O
transfer	O
.	O
</s>
<s>
Alternators	B-Algorithm
can	O
also	O
be	O
water-cooled	O
in	O
cars	O
.	O
</s>
<s>
Larger	O
vehicles	O
may	O
have	O
field	O
coil	O
alternators	B-Algorithm
similar	O
to	O
larger	O
machines	O
.	O
</s>
<s>
The	O
windings	O
of	O
a	B-General_Concept
3	O
phase	O
alternator	B-Algorithm
may	O
be	O
connected	O
using	O
either	O
the	O
delta	O
or	O
star	O
(	O
wye	O
)	O
connection	O
regime	O
set-up	O
.	O
</s>
<s>
Brushless	O
versions	O
of	O
these	O
type	O
alternators	B-Algorithm
are	O
also	O
common	O
in	O
larger	O
machinery	O
such	O
as	O
highway	O
trucks	O
and	O
earthmoving	O
machinery	O
.	O
</s>
<s>
Automotive	O
alternators	B-Algorithm
require	O
a	B-General_Concept
voltage	O
regulator	O
which	O
operates	O
by	O
modulating	O
the	O
small	O
field	O
current	O
to	O
produce	O
a	B-General_Concept
constant	O
voltage	O
at	O
the	O
battery	B-Algorithm
terminals	O
.	O
</s>
<s>
Early	O
designs	O
(	O
c.1960s	O
–	O
1970s	O
)	O
used	O
a	B-General_Concept
discrete	O
device	O
mounted	O
elsewhere	O
in	O
the	O
vehicle	O
.	O
</s>
<s>
Intermediate	O
designs	O
(	O
c.1970s	O
–	O
1990s	O
)	O
incorporated	O
the	O
voltage	O
regulator	O
into	O
the	O
alternator	B-Algorithm
housing	O
.	O
</s>
<s>
Modern	O
designs	O
do	O
away	O
with	O
the	O
voltage	O
regulator	O
altogether	O
;	O
voltage	O
regulation	O
is	O
now	O
a	B-General_Concept
function	O
of	O
the	O
engine	B-Device
control	I-Device
unit	I-Device
(	O
ECU	O
)	O
.	O
</s>
<s>
The	O
field	O
current	O
is	O
much	O
smaller	O
than	O
the	O
output	O
current	O
of	O
the	O
alternator	B-Algorithm
;	O
for	O
example	O
,	O
a	B-General_Concept
70	O
A	B-General_Concept
alternator	B-Algorithm
may	O
need	O
only	O
2-3	O
A	B-General_Concept
of	O
field	O
current	O
.	O
</s>
<s>
The	O
low	O
current	O
and	O
relatively	O
smooth	O
slip	O
rings	O
ensure	O
greater	O
reliability	O
and	O
longer	O
life	O
than	O
that	O
obtained	O
by	O
a	B-General_Concept
DC	O
generator	O
with	O
its	O
commutator	O
and	O
higher	O
current	O
being	O
passed	O
through	O
its	O
brushes	O
.	O
</s>
<s>
The	O
field	O
windings	O
are	O
supplied	O
with	O
power	O
from	O
the	O
battery	B-Algorithm
via	O
the	O
ignition	O
switch	O
and	O
regulator	O
.	O
</s>
<s>
A	B-General_Concept
parallel	O
circuit	O
supplies	O
the	O
"	O
charge	O
"	O
warning	O
indicator	O
and	O
is	O
earthed	O
via	O
the	O
regulator	O
(	O
which	O
is	O
why	O
the	O
indicator	O
is	O
on	O
when	O
the	O
ignition	O
is	O
on	O
but	O
the	O
engine	O
is	O
not	O
running	O
)	O
.	O
</s>
<s>
Once	O
the	O
engine	O
is	O
running	O
and	O
the	O
alternator	B-Algorithm
is	O
generating	O
power	O
,	O
a	B-General_Concept
diode	O
feeds	O
the	O
field	O
current	O
from	O
the	O
alternator	B-Algorithm
main	O
output	O
equalizing	O
the	O
voltage	O
across	O
the	O
warning	O
indicator	O
which	O
goes	O
off	O
.	O
</s>
<s>
The	O
drawback	O
of	O
this	O
arrangement	O
is	O
that	O
if	O
the	O
warning	O
lamp	O
burns	O
out	O
or	O
the	O
"	O
exciter	O
"	O
wire	O
is	O
disconnected	O
,	O
no	O
current	O
reaches	O
the	O
field	O
windings	O
and	O
the	O
alternator	B-Algorithm
will	O
not	O
generate	O
power	O
.	O
</s>
<s>
Some	O
warning	O
indicator	O
circuits	O
are	O
equipped	O
with	O
a	B-General_Concept
resistor	O
in	O
parallel	O
with	O
the	O
lamp	O
that	O
permit	O
excitation	O
current	O
to	O
flow	O
if	O
the	O
warning	O
lamp	O
burns	O
out	O
.	O
</s>
<s>
The	O
driver	O
should	O
check	O
that	O
the	O
warning	O
indicator	O
is	O
on	O
when	O
the	O
engine	O
is	O
stopped	O
;	O
otherwise	O
,	O
there	O
might	O
not	O
be	O
any	O
indication	O
of	O
a	B-General_Concept
failure	O
of	O
the	O
belt	O
which	O
may	O
also	O
drive	O
the	O
cooling	O
water	O
pump	O
.	O
</s>
<s>
Some	O
alternators	B-Algorithm
will	O
self-excite	O
when	O
the	O
engine	O
reaches	O
a	B-General_Concept
certain	O
speed	O
.	O
</s>
<s>
In	O
recent	O
years	O
,	O
alternator	B-Algorithm
regulators	O
are	O
linked	O
to	O
the	O
vehicle	O
's	O
computer	O
system	O
and	O
various	O
factors	O
including	O
air	O
temperature	O
obtained	O
from	O
the	O
intake	O
air	O
temperature	O
sensor	O
,	O
battery	B-Algorithm
temperature	O
sensor	O
and	O
engine	O
load	O
are	O
evaluated	O
in	O
adjusting	O
the	O
voltage	O
supplied	O
by	O
the	O
alternator	B-Algorithm
.	O
</s>
<s>
Older	O
automobiles	O
with	O
minimal	O
lighting	O
may	O
have	O
had	O
an	O
alternator	B-Algorithm
capable	O
of	O
producing	O
only	O
30	O
amperes	B-General_Concept
.	O
</s>
<s>
Typical	O
passenger	O
car	O
and	O
light	O
truck	O
alternators	B-Algorithm
are	O
rated	O
around	O
50	O
–	O
70A	O
,	O
though	O
higher	O
ratings	O
are	O
becoming	O
more	O
common	O
,	O
especially	O
as	O
there	O
is	O
more	O
load	O
on	O
the	O
vehicle	O
's	O
electrical	O
system	O
with	O
air	O
conditioning	O
,	O
electric	O
power	O
steering	O
and	O
other	O
electrical	O
systems	O
.	O
</s>
<s>
Very	O
large	O
alternators	B-Algorithm
used	O
on	O
buses	O
,	O
heavy	O
equipment	O
or	O
emergency	O
vehicles	O
may	O
produce	O
300A	O
.	O
</s>
<s>
Semi-trucks	O
usually	O
have	O
alternators	B-Algorithm
which	O
output	O
140A	O
.	O
</s>
<s>
Very	O
large	O
alternators	B-Algorithm
may	O
be	O
water-cooled	O
or	O
oil-cooled	O
.	O
</s>
<s>
Efficiency	O
of	O
automotive	O
alternators	B-Algorithm
is	O
limited	O
by	O
fan	O
cooling	O
loss	O
,	O
bearing	O
loss	O
,	O
iron	O
loss	O
,	O
copper	O
loss	O
,	O
and	O
the	O
voltage	O
drop	O
in	O
the	O
diode	O
bridges	O
.	O
</s>
<s>
At	O
medium	O
speeds	O
efficiency	O
of	O
today	O
's	O
alternators	B-Algorithm
is	O
70	O
–	O
80%	O
.	O
</s>
<s>
This	O
betters	O
very	O
small	O
high-performance	O
permanent	O
magnet	O
alternators	B-Algorithm
,	O
such	O
as	O
those	O
used	O
for	O
bicycle	O
lighting	O
systems	O
,	O
which	O
achieve	O
an	O
efficiency	O
around	O
60%	O
.	O
</s>
<s>
Larger	O
permanent	O
magnet	O
electric	O
machines	O
(	O
that	O
can	O
operate	O
as	O
motors	O
or	O
alternators	B-Algorithm
)	O
can	O
achieve	O
today	O
much	O
higher	O
efficiencies	O
.	O
</s>
<s>
Hybrid	O
electric	O
vehicles	O
replace	O
the	O
separate	O
alternator	B-Algorithm
and	O
starter	O
motor	O
with	O
one	O
or	O
more	O
combined	O
motor/generator	O
( s	O
)	O
that	O
start	O
the	O
internal	O
combustion	O
engine	O
,	O
provide	O
some	O
or	O
all	O
of	O
the	O
mechanical	O
power	O
to	O
the	O
wheels	O
,	O
and	O
charge	O
a	B-General_Concept
large	O
storage	O
battery	B-Algorithm
.	O
</s>
<s>
When	O
more	O
than	O
one	O
motor/generator	O
is	O
present	O
,	O
as	O
in	O
the	O
Hybrid	O
Synergy	O
Drive	O
used	O
in	O
the	O
Toyota	O
Prius	O
and	O
others	O
,	O
one	O
may	O
operate	O
as	O
a	B-General_Concept
generator	O
and	O
feed	O
the	O
other	O
as	O
a	B-General_Concept
motor	O
,	O
providing	O
an	O
electromechanical	O
path	O
for	O
some	O
of	O
the	O
engine	O
power	O
to	O
flow	O
to	O
the	O
wheels	O
.	O
</s>
<s>
These	O
motor/generators	O
have	O
considerably	O
more	O
powerful	O
electronic	O
devices	O
for	O
their	O
control	O
than	O
the	O
automotive	O
alternator	B-Algorithm
described	O
above	O
.	O
</s>
