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NASA
TECHNICAL
NASATN D-8508
NOTE
O !
Z I--
Z
A NICKEL-CADMIUM
BATTERY
RECONDITIONING
CIRCUIT
Roy Lanier George C. Marshall Marshall NATIONAL
Space Flight
Space Flight
AERONAUTICS
AND
SPACE
Center
Center, Ala. ADMINISTRATION
•
35812 WASHINGTON,
O. C.
•
JUNE 1977
1.
REPORT
NO.
2.
GOVERNMENT
ACCESSION
NO.
3.
RECIPIENT'S
CATALOG
5.
REPORT
DATE
June
1977
NO,
NASA TN D-8508 4.
TITLE
AND
SUBTITLE
_A Nickel-Cadmium
Battery
Reconditioning
6.
Circuit
7. AUTHOR(S) Roy Lanier 9. PERFORMING ORGANIZATION NAMEANDADDRESS George
C.
Marshall
Marshall Space
Space
Flight
Flight
Center,
SPONSORING
National
AGENCY
NAME
Aeronautics
Washington,
AND
1.
CONTRACT
OR
GRANT
NO.
TYPE
OF
REPOR',
&
PERIOD
COVERED
ADDRESS
and Space
D.C.
CODE
35812 3.
2.
ORGANIZATION
8.PERFORMING ORGANIZATION REPORt# M-221 10. woRKUNIT NO.
Center
Alabama
PERFORMING
Administration
Technica] 14.
20547
Note
SPONSORING
AGENCY
CODE
15. SUPPLEMENTARY NOTES Prepared 6,
by Electronics
The
that
circuit
battery
_'ground-type" recondition
Laboratory,
high
with
(greater
(100
voltage
than
even
This report to its use.
voltage
after
Science
and
and
small
is simple
assembly,
yet
to 150 Vdc) systems
have
counterpart,
and
battery
in low
orbit
this
circuit
nameplate
over
20 000
Earth
that can
power
returns
a greater
and
simulated
orbital
Unclassified
(o_
thLI
report_
for
used to show
of its
new battery
a 4 year
period.
The
implications
reconditioning the
are
than
expected
its
life
in
that low
of a
be up to 5 years.
18.
CLASSIF.
when results
90 percent
a typical
cycles
techniques,
WORDS
SECURITY
circuit These
than
in a
of a complete
circuit and makes recommendations (22 to 36 Vdc) power systems and
for battery
circuit
to be included
advantage
Oll the given.
follows
is discussed.
need
these
the
to greater
capacity)
systems
using
enough
provides
DISTRIBUTION
STAR
19.
Engineering
Test results batteries are
addresses applications of the Its application in low voltage
voltage
KE_
paper
control
reconditioned curve
high
in this
battery reconditioning discharge. two 24 cell, 20 A-h nickel-cadmium
capacity
degradation
relative
presented
charge/power
a battery
original
17.
Control
ABSTRACT
typical
the
and
20.
SECURITY
CLASSIF.
(of
thL.
STATEMENT
Category
44
page)
21.
Unclassified *For
sale
NO.
OF
PAGES
29 by
the
National
Technical
Information
Service,
22.
PRICE
$4. O0 Springfield,
Virginia
22161.
TABLEOF CONTENTS
Page SUMMARY
.......................................
INTRODUC
TION
BACKGROUND
................................... ....................................
SYSTEM
DESCRIPTION
..............................
CIRCUIT
DESCRIPTION
..............
CIRCUIT
APPLICATION
..............................
TEST
RESULTS
OTHER
Capacity
Battery
Voltage Results
APPLICATIONS
CONC LUSlON REFERENCES
................
8 i0
....................................
Battery Other
1
13 13
.............................. Characteristics
....................
................................
15 15
..............................
22
.....................................
23
....................................
24
iii
LIST OF ILLUSTRATIONS
Title
Figure I.
,
3.
,
Battery Cyclic
life
ATM Life
capacity test
test
Simplified
.
Battery
Power
configuration flight
V for
System
.
Battery
mismatch
Typical
end
.....
3
...................
circuit
circuit
output
Energy extraction from battery reconditioning .............................. 2 voltage
battery
........................
reconditioning
Battery
a 20 A-h
......................
reconditioning
,
I0.
26.4
capacities
Electrical
.
.
above
Page
discharge
Ii.
Battery
2 cell
voltages
12.
Battery
1 recharge
17
................
18
before
and
after 19
at end
fraction
12
_irst
.................
voltage
..............................
.....
16
characteristics
of discharge
characteristic
2 during
profile
reconditioning
11
..............
of discharge
anomaly
iv
...........
...............
20 21
A NICKEL-CADMIUM BATTERY RECONDITIONING CIRCUIT SUMMARY
The
degradation
cadmium
battery,
in space
electrical
of the
sometimes power
battery
at some
minimum
for bus
regulation
for
low voltage
sense
the
percentage
1.0
to 1.1
upon
parameters
reconditioning,
a predetermined battery has
and
The
The
voltage
and
temporary.
for
a load
flight.
on the
for this
a battery
enhancement
obtained
in this
a battery
for
loading
the
has
in the
past
reconditioning, the
bus,
battery
manner
has
typically dependence
graphically.
discharging
from
cycling,
voltage,
degradation
process
the
and
by individually
battery
and discharging
required
time
is demonstrated ground
Flight
of removing
resistor,
life
in the
by an automatic
with
voltage
of completely
done required
space
consisted
with
consists
been
equipment
complex
typically
battery
has
cycle
stored
is normally
at a particular The
is a problem
energy
shut-down
because,
available
and
which
time,
cells.
bulky
energy
significantly.
of the
voltage
system
occurs
of a nickel-
_' or "fading,"
on use
A minimum
problem
battery
decreases
effect
depend
and to preclude The
characteristic
TTmemory that
voltage.
users
of total
V/cell,
discharge
called systems
device.
environmental
Battery
voltage
loading
to 0.9
been
been
when the
to 1.0
shown
too
used, entire
V/cell.
to be minimal
INTRODUCTION
(Ni-Cd)
Nickel-cadmium storing tion,
electrical which
space cells
connected
store
These in series,
batteries. energy
use
later
are treated with care, where DOD is defined
vehicles
batteries, may
supplied orbit.
have
been
designed
discharge-charge typically
by a solar
limiting as:
the
primary
for
alone array)
temperature
the
with
or in parallel
the batteries
reliable,
during long life and
means
low Earth since
constructed
applications,
To assure
the
cycles,
be operated
In all of the
(usually in the
on space
repeated
exploration.
identical for
energy
require
batteries
depth
orbit
opera-
inception
of
18 to 30 Ni-Cd with
are
of
other
called
nearly
upon
to
a portion
of the
orbit
operation,
the
batteries
of discharge
(DOD)
DOD=
(A-h
out/A-h
rated)
x 100%
where
DOD
= batter5
A-h out = the A-h
rated
= the
In spite
of this,
Ni-Cd
degrade
with time
depth
oi discharge
ampere
hours
battery
rated
batteries
as shown
discharged capacity.
voltage
in Figure
capacity
characteristics
typically
1.
The battery voltage degradation, sometimes
called "memory"
or "fading,"
depends on several parameters
such as charge characteristics, temperature,
and DOD.
because the battery is used as a voltage source,
It causes a problem
and if the energy is not available at or above some cannot use this energy. V/cell. the
In addition,
potential
on one
The reversible
process,
and the
called
discharged been
battery
generally
cell been
reliability, this
in a space is capable battery. circuit, ures. only
2
some
in a Ni-Cd
considered valid.
approximately of providing
the the
are This size
each
report
of two 20 A-h
necessary
operations
However, heavy
A recent
presents for
a ground
reconditioning operation,
of Ni-Cd and
flight
batteries
reconditioning
report
need
that cells
is com-
and flight
has use
[1] can
has
discharging
this
where
recognized be packaged and
a Ni-Cd
as the battery certain battery
no longer
need
state
of a battery
reconditioning
The circuit reliability can be of the same order and the circuit can be designed to protect against Thus,
for
a circuit or larger
a
Reconditioning loading
network.
at a premium.
is largely
in the battery
of time.
and/or
reversing
cells.
to its original
by individually bulky,
risks
these battery
cell
period
resistor
too complex,
and space
as still
whereby
and
level
damaging
can be restored
predetermined
a relay
this
degradation
on the ground
through
below and
characteristic
performed
weight,
limitation
voltages
in a battery
"reconditioning" for
voltage the system
acceptable voltage is usually 1.0 to I. 1
at cell cells
characteristic
historically each
operation or more
voltage
by a process pletely
The minimum
minimum
charging fail-
be considered
not be considered
as a
140
]
120
>-
100
5 <
oOc
Q.
< {D t_
80
UJ
I< at" IZ I.IJ
60
o nr" 0.
40
20
0
!
0
Figure
2
i.
Battery
I
4
capacity
I
6 THOUSANDS above
26.4
I
8 OF ORBITS V for
a 20
A-h
I
1
10
12
battery.
superficial enhancement without
discharge at best.
bulky
equipment,
operations, life
to only 0.9 to 1.0 V/cell which provides a brief voltage Reconditioning of batteries in space can be accomplished
using
operations
this
and circuit.
in space
presented to provide and reserve capacity
to the
degree
previously
Electrical
should
realize
power
available
syster_s
a significant
reconditioning assuring throughout the mission.
designed
advantage
adequate
only
for
using
voltage
in ground the
long circuit
characteristics
BACKGROUND
A Charger/Battery/Regulator two CBRM'
s in October
Telescope Part four
Mount
Module
1972
(ATM)
to establish
batteries
during
No. 40M26202, Serial numbers 20 A-h Ni-Cd sealed cells with
signal
electrodes
overcharge
were
in the The
The
charge
15 A to a temperature in a tapering
electrode. typically
for
on the
compensated
voltage.
current,
DOD averaged Recharge
in/A-h
upcoming
The
fraction
A-h A-h
heat
on
Apollo batteries,
was and
to minimize removal.
58 and limited
voltage
is defined
The
battery
were
25 percent,
was
then
terminated the
35 min, mode
recharge
of up to
held
constant,
by the fraction
signal was
as:
(i)
out)
where
RF
of the radiative
charge
initiated
Skylab
assembled from twentysignal electrodes. The
of a current
until
was
mission.
and
batteries
test
of the
_ere
passive
consisted
to 1.10.
RF = (A-h
cycles
charge
the
termination
used
regime
The battery 1.05
charge
life
capabilities
80 and 84, recombination
which
charge-discharge
respectively. resulting
used
application
(CBRM)
the
= the battery
recharge
fraction
in
= the
ampere
hours
charged
out
= the
ampere
hours
discharged.
Battery temperatures were maintained between5°C and 15°C by controlling the CBRM radiative view factor to a cold plate in the vacuum environment of the test. All of these factors were consistent with expected Skylab flight conditions. The test ran for approximately 7 months (3000 orbits) with expected results prior to the Skylab launch. The Skylablaunch was marred by the failure and loss of a heat shield on the Orbital Workshop (OWS), which caused the loss of one of two solar wings on the
OWS,
deployed heat
and
with
shield
the
loss
in a direction
This
phase
of the return
to have became
capacity it was
a test
loss with
known
the battery
The
recharging
limitation a ground
the
cells
because
of the
large
problem
indicateda
test
as
subject
to meet
a test
bed.
of this
a tried This
Skylab
hardware
procedure
complex
equipment a battery
The
for
need
has
been
circuit
reversal
and
developed
and the
to correct
most
tested
test
2,
However, effects,
of the space
it.
The
results
the
and
useable
for
flight Skylab
applicable using
a
the
discharging
its damaging
method
and
imme-
in Figure
to implement
developed
were
test
to restore
proposed
reconditioning
entire
unsuccessful.
restore
not been
required
life
of completely
would had
the
and the
a method
Efforts were
the
During
ATlvl batteries
as shown
procedure
procedure
with for
The
and,
experienced.
need this
simulated
cell
power
to define
was
against
using
battery.
A solution
of the
arrays
OWS living
operation
the
the
solar
of the
capacity.
attempt
was
However,
ATM
OWS problems,
conditions,
and
wing
of 15 ° to 30°C. supplied
of useable
was
system
of the
operating
reconditioning
protecting
of the
system
capacity
the
capacity
power correction
anomaly
that
of power
This
later.
and the overheating
temperature
to evaluate
of usable
cells,
ATM
wing.
weeks
vehicle
and
10 to 12 A-h
bed
several
days
normal
only
OWS solar
Sun to prevent
of a crew,
to near
anomaly.
comparable
the
balance the
other
of the
in several
mission
subsequent
flight
crew
energy
arrival
discovered this
of the orientation
resulted
After
diately
the
assistance required
at or near
vehicle.
to deploy
40 ° to 60 ° from
quarters. batteries this
a failure
to flight. CBRM
obtained
are
life the
report.
SYSTEM DESCRI PTION
The considered
block typical
It is characterized
diagram
of the
of systems by multiple
ATM
in which parallel
Electrical
Power
a reconditioning energy
System circuit
storage/power
in Figure would
3 is
be useful.
processing
stages
5
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and multicell capability
Ni-Cd to isolate
energy
sharing
those
which
during
the
current,
ATM
batteries
that
were
storage.
The
reconditioning have
and
the
from
system
and
been
also
to assure
recently
electrode
has
the
proper
reconditioned
portion
of the The
sharing
the
solar sensed
voltage,
and
without
orbit,
and
batteries were protected the battery if its voltage
solar
array
current
the
solar
discharged the
output
approximately
from cell fell below
charger
voltage,
collapsing
shared
to assure
by the
battery
the battery
regulators
circuit
arrays
charger
charging
the loads.
load
from The
battery
"night"
each battery. The which disconnected
orbit.
signal
proper
the
charged
of the
to supply
on a signal
for
batteries
to assure
During
energy
batteries
portion
temperature
regulator
for
not.
"day"
voltage
array. the
the
between
have
The
and
batteries
through load
equal
based DOD in
reversal by a circuit 26.4 V ( 1.1 V/cell).
The lifetest configuration being used as a test bed for the reconditioning circuit discussed herein consists of two of the para]]el elements from the ATM Electrical Power
System
as shown in Figure 4.
CIRCUIT DESCRIPTION
A circuit objectives.
The
in the battery results
requirements
are
that
it must
completely
discharge
not allow
the
polarity
of any
to be reversed.
it must
the
later
to restore
or greater
of its
will
requirements.
useable
capacity
circuit
It should
be very
probably
fully
automated,
practical
time.
Cost
that
reduced
number
capacity
for
small
result
some
key
and should
from
This
complete
the
required will
far
desired will
time
size.
the
every
than
0.5
for
reliable
cost
of the
a recon-
desirable
as practical. be easy
reconditioning replacing
V/cell
and
be generally
of having
Test
greater
constraints
It should
cell
90 percent
objectives
is not a key
between
as a result exceed
and
and
25 percent
on system
the but
to less
is typically
that
to the battery
extending
mission
The
requirements
to approximately
be as simple
be minimized,
cell
discharge
objectives
should
several
capacity
depending
should
compared
meet
that
capacity.
circuit
of batteries
a given
shown useable
somewhat,
However, The
must
of the battery.
vary
be described.
savings
have
the battery
initia]
nameplate
ditioning may
a battery
to be discussed
is adequate than
and
to recondition
in the
feature
least
because
batteries a greater
to use, the
or the useable
reconditioning
circuit.
o0
a o _I
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TM
--
A circuit is shown and
in its
used
simplest
the previously the
of reconditioning
in Figure
2.
voltage
The
full
wave
ability
circuit total
the
exotic
output
current
at the
current
erated voltage
the
circuit
outputs.
1.5
and to enhance
the for
output
continuing components.
the
the
20 A-h
to
battery No
diodes
the
heat
characteristic
are
gen-
of the
battery
reconditioning
10 W
signals
hot carrier
voltage
a 22 cell,
350 cm 3, excluding
provide
to minimize
cell.
and
circuit
However,
a low
breadboard
output
logic
shown
battery
The
voltage
rectifiers
are
with
each
to assure the
is required. output
converter
associated
The
later
is provided.
s relays
breadboarded
discussed.
with
A/low
protecting
objectives
been
in detail
dc-to-dc
making
resistor' while
circuit
has
in parallel
and
and
previously
of a simple connected
low voltage
A typical
in approximately
batteries
circuit
or circuitry
for
in the
load rate
circuit
to be discussed
decision
sense
desired
components
recommended
for
requirements
This
to approximately
reconditioning
discharge
two test
consists
The
5.
batteries
circuit
is limited
output.
switch
the
rectified
to sense
tested
stated
fo_-rn in Figure
in reconditioning
results
The
to satisfy
low
can be packaged
resistors
and
relays.
CIRCUIT APPLICATION
The
following
breadboard
circuit
reconditioning vary
circuit
in certain
design
and
aspects.
A typical The
tested
has
ditioning
three
battery
cell
reverse
biased.
voltages
conduction. shows
that
hot-carrier
10
are
Standby
the
will
be low enough output
transition
diodes
this
greater in the cell
The this
5, outputs
for
circuit
voltages its
characteristic begins could
be 0.5
V.
system
When
inactive
V and than
and
the
and As
output
1 W for
outputs
of approximately the
the
the
because
at some
occurs
in this
configuration
low voltage
this
by proper
charge
regulator,
low voltage
voltage
could
V/cell
and 2(; ohms.
is less
associated
(1.1 The
are
1.0
drop
of the at a cell
limit
15,
than
application
can be realized
energized.
low voltage
typically power
the
of any
by terminating
to its lower are
to the
be typical
later.
is implemented from
primarily
a specific
that
combinations, the
discharges,
for
advantages
resistors
resistor
would
will be discussed
disconnected load
starts,
voltages
As the battery cell
and
load
unique
circuit
applies
operation
operation
it to discharge
is then
circuit
discharge
but
operation
This
reconditioning
allowing
battery
reconditioning
5.
type,
Some of the
battery
and
of circuit
in Figure
of this
application
on a battery test).
description shown
diodes this
point output
recon-
the are
condition.
one
of the
to begin
in Figure 0.7
V.
reconditioning
6 For
A
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OUTPUT Figure
circuit
begins
to equalize the
until
to 0.5
12
The
load
the and
require
circuitry
signal
discharge
final can
continues
required
discharge, over solar
the
entire
load
to discharge
discharge
is trickle
char_ed
sunrise.
The
the
ntm_ber
capacity.
from is This
at a battery
in parallel
cells
increase
sequence
battery
of orbits,
power
a step
is selected.
at an orbit
a series array
handle
for the
more for
This
value
to completely
the
on line
rate.
resistance
battery
placed
is a tendency
voltages
circuit as
there
cell the
the
characteristic.
oul;put
and logic
the
charge
reserve
so that
The
of the
completes
until
as long and
load
1.0
- AMPERE
circuit
decreasing
decreasing
so that
A-h
cell
sense
rate
V/cell.
completion
to 1 or more on the
the low
thus
outputs
reconditioning
current
at the lower
voltage
Upon and
the
is chosen
of 0.2 low
to share
resistance,
repeated value
Battery
in voltage.
circuit
in load
6.
CURRENT
i
voltage
with
the
the battery. at a 1 A rate charger of which
takes
over
depends
TESTRESULTS
A summary is shown in Figure as follows.
of the results of reconditioning th,e two life 2 and the Table. These and related results
test are
batteries discussed
Battery Capacity The ATM
load
mately
battery
capacities
(Fig.
7 A.
discharged
3) that
The
discharge
rate.
energy
storage
capacity,
voltage
(2). provide
for
is available restores
performance nameplate
to hold
the battery
battery
was
The least
data
last
protecting
cells
slightly
was
first
low grade weaker
at 0.3
in that
The
first
V for
energy and
first
reconditioning subsequent
for
4 days
and then
with
22 800 orbits
resulted
similar
results.
in slightly
V ( 1.1
retains only
its
as described this and
is V/cell)
original
at low rates by
Bauer
limitation rate
and
at which
reversal.
This
upon
completion
of reconditioning
it
apparently the
performance. Original capacity for was 26 to 28 A-h. The time allowed and
to the
the length
rate
of time
and degree
battery
2 was
a 3 day
reconditionings. discharged
for
discharge
capacity
produced discharge
However, 3 days run
restoration
since
the
of recovery.
of each
A method used to determine the degree of discharge to measure the cell discharge current into a diode and 0.5 The data ditioning
battery
from
A 5 day higher
still
plates
the
of 26.4
recognize
on battery
than
discharged
cell
reconditioning
effective
reconditioning
limit
at a voltage
discharge
contribute the
on the
of approxi-
when
is available
procedure
cells
structure,
this
less
and
an average
current
energy battery
energy
growth
with
discharge
degraded
is near its original of the type tested
cells
recovery.
was
plate
measured
protection
of the
circuit
reconditioned
reflect
the
but much
of this
original
battery 20 A-h
voltage
of crystal
extraction while
the
automatic
reconditioning
were
is the available
Apparently
as a result The
tests
in an average
capacity
CBRM
at this and
resulted
recorded
to the
in these
on the
the and
battery
3
second
at approximately in both
batteries.
of the batteries was ohm resistor network.
for the highest cell discharge current in a battery at the end is given in column 6 of the Table. This current is somewhat
of a reconindicative
13
O_
0 ¢xl
¢xl ¢xl
O_
I
I
¢_
_o
_f o hn
0
o
o Z 0
0 I ¢x1 ¢q
¢q
¢xl
Cxi
0 L_ 0 o._
0_
0
c_
o
b-
cO
¢xl
O_
0
_q
oO
O0
O0
LQ
D'-
O0
_D
O_
r-_
Cq
o_
0
Oo
+ c;
14
_"
¢xl
cO
oO
[_-
Cxl
Cxl
Cxl
¢xl
Cxl
of the energy remaining in a battery and implies that, for the cells tested, after 5 days of discharge there is essentially no energy in the cells. However, after 3 to 4 days discharge there is little gain in additional post-reconditioning capacity. Figure 7 showsthe capacity taken from battery 2 on its first reconditioning with the test circuit. The sharp knee at 25 h is the point beyondwhich very little additional energy is extracted from the battery and indicates that 25 to 30 h may provide adequatereconditioning. Until the process is better understood, a test program is recommendedto establish the minimum acceptable discharge time for proper reconditioning. Data to date indicate that a time between 2 and 5 days is optimum.
Battery Voltage Characteristics The
key
age source characteristics ditioning,
and
DOD),
parameters
the
hundred after
points
characteristics
Figure
reconditioning.
than
3 weeks
This
dictates
load
and
and
overheating
that
for
the first
for
the
curve
taken
3 A-h
not been
the
rate
typically
has
at which
the
the
300 or more
approach
of sharing
the
load
same
between
reconditioned
as
a volt-
(15
percent
immediately
up to 15 percent
are
of a newly
a l_attery
the mismatch
the batteries
a method
using
8 shows the discharge immediately after recon-
one which
10 shows There
before
when
Note
except
9 shows
battery
orbits.
later.
match
Figure
reconditioned
consideration
characteristics. Figure 2 prior to reconditioning,
at several
reconditioning. newly
under
is its discharge for battery
after
DOD between
reconditioned
for
characteristics orbits
converge
representing
discharge batteries
a
several more
characteristic. to preclude
over-
battery.
Other Results An unexpected connection
with
two
An erratic approximately compared tions over the with
from
anomalies
that
end a typical
is not known was
occurred
at the
discharged
cell
Figure
cell
with
time. several
voltage
voltage cause
However, capacity
the tests
voltage test,
observed
the
The
the
was
observed
in
the test.
was
11 shows
to the automatic A reconditioning
the batteries
during
in the battery.
present
of 6 months
no improvement.
reconditioning
of discharge
14 000 orbits. with
a period battery
benefit
of the
of the
protection
2 at
erratic
voltage
fluctuations (Note
fourth
in battery
cell fluctua-
were
observed
1 in Fig.
11)
limit
of 1.1
on battery
2,
was
where V/cell then
15
4O
ALL CELLS BEING BY RECONDITIONING O3. re
HELPED CIRCUIT
30
Q
= I,U (:Z: I.U a.
(z3 ,-I ,..I I,M
20
O ¢Z: t,l,.
RECONDITIONING BEGINS HELPING
>I-
CIRCUIT CELLS
¢..)
rj 10
END OF DISCHARGE TO LOAD
(o
_o
io
4'o
DISCHARGE
Figure
7.
Energy
during
16
TIME
extraction first
reconditioning.
._o
do
7'0
- HOURS
from
battery
2
0 Z 0 I-Z (.Jo I_
÷
rf"
? 0
+
0
o ?
rr -_
b_
T
._ ¢.)
uJ
>F-
1,--
0 >
4.1.
U.I
m
_
g
I%(_
,{_
('_
SJ.IOA
0
(%1
- 3D'v'I7OA
A_311VB
17
BEFORE
RECONDITIONING
v_
Z I
°_,_
Z 0
c_
I--o
Z 0
LU C.)
t-
LLI
00
r_
c_ c_
_z
0 _Z _
_w
cD 41
0 U,.
0
r_
Q Z 0 D 0 I-
o
(.D c_
N
0
©
,,....,4
c,D _"
w ct.
>.. j.-
0
<
>. L.U
O0
0
SITOA
" 39VI-IOA
JkEI311V8
17
j l...l
°,,-i
¢o Iii
c.) iii rl
¢D
iii ID
Z
'1-
Z O
C_
I-
ii
z O
O "1I-
iit
01:: ci.
S/70A
18
" 39V.I.7OA
Atd:I.LI_V8
iii
a
°_1
.,i-;i
31 -"
03 I-" --I O > LU
L9 < I.,J
o > LU (..9
A 30
< -j..
BATTERY
2- 9342 ORBITS
E3 U-
O E3 Z LU
BEFORE RECONDITIONING
29
I
I
I
200
400
600
ORBITS AFTER
Figure
10. before
Typical and
end after
RECONDITIONING
of discharge
voltage
reconditioning.
19
w
/
c_
q9
m °,,_
_z
n_
__o >._-
o
_a
I-"
_z <_,,, _mr
'-
O I.I..
4-)
cd
O
_cq
c_ z 0 0 .I-
c_
°._
M N .=I W
..J -J
I
SllOA
2O
/
I
- 39VllOA
II:ID
performed, than 1 year function
and the cell voltage since, the anomaly
normally. The
test
recharge
conditions.
Figure
by three
12.
efficiency tioned,
fraction
After
is controlled
The the
and
recharge
the
cent
approximately
cause
after recharge
collecting
recharge
on the
20 000 orbits,
fraction a battery fraction
again is that
signal
continued
to rise rise.
returned some
electrodes
to increase
battery
to normal. form
as
was
and being
1600
orbits,
shown and
the which
as shown
battery
in
causing was
in the
to 118 per-
reconditioned,
A theory
as to the or
redistributed
gas
during
an
recondifigure.
returned
again
of contamination
under fraction,
to rise
The
to normal
began The
for
to 1.10
recharge
began
temperature again
1.08 the
electrodes,
returned
2 months.
anomaly
1 is normally
signal
fraction
fraction
of this
approximately
recharge
decrease and
in battery
redundant
However, the
stabilized as shown in the figure. In more has not reoccurred and the cell continues to
and
possible
bubbles
is
reconditioning.
1.20
1.18
RECONDITIONED
1.16
I
1.14
1.12
1.08 1" I.,u r_
1.06
1.04
1.02
l'O0_v_
v 2_1
20 THOUSANDS
Figure
12.
Battery
OF
1 recharge
2'2 ORBITS
fraction
anomaly. 21
However, the condition must occur on all three signal electrodes to causethe anomaly. In addition no evidenceof this sort of anomaly has occurred in battery 2. Even so, a reconditioning did correct a situation that could cause battery overheating and subsequentloss. A reconditioning at 2 month intervals would be small cost to save a battery on a mission.
OTHERAPPLICATIONS
The
discussion
of the
circuit
its designed use to protect a battery other potential uses for the circuit The use
circuit
may
it as a detector
for
of discharge across the
to allow
reconditioning when
the
be connected low cell
of the battery entire battery
requirement cell
cell
voltage
voltage.
This
will
individual
cell
voltage
current
sense
The
indicating discharge
has
for
considering
activated
normally
battery
cell discharge and initiate
been
reconditioning.
of discharge protection.
in the
collapses.
far
and
mismatch
senses
and gives an output signal would be used to terminate
5 thus
to the battery
before termination and provide better
for
circuit
in Figure
during discharge are now considered.
Some
continually
to
greater
depth
allow
than a voltage sensor This results from the
sense
circuit
by assuming circuit
the
cell
load
the
detects
or failure. other action
while the
collapse
This signal as deemed
necessary. The failure maximum ure
next
step
bypass. load
modes.
beyond
If the current
Typical
tioning or two,
22
to a good circuit
failure
the
circuit
modes
detection
circuit
are
can open
and
indication
is designed
overcome circuit
certain or short
to
is cell
handle battery
circuit
the failof a
nature inside the cell. Early ceils similar to the type with high impedance shorts that exhibited characteristics
cell
could
and thus
or failure
reconditioning
of a cell, cell
low or high impedance used in this test failed similar
discharge
battery
during supply
prevent
charge the
failure
load
but
had no output
for a small
of an entire
under
number
battery
load.
of cells,
as a result
The
recondi-
probably of cell
one
failures.
CONCLUSION
The restoring
reconditioning the
effective
all
battery
cells
the
circuit
was
system Use
and
while
or assist
the
to be even
sense weak
space
for
future
large
are
both
multiplied
120 series
are
cells
will
systems.
type
The
a circuit
which
were
considered
Earth
orbit
space
are
power
protection
in the
matching
bus
a useful
applications,
have
well. of using
failure with
life
of approximately
a
cell
is considered
of approximately The
compared
to
It is anticipated
scheme
higher
reliability.
discussed Ni-Cd
2 years to last
Significant advantages and cost the techniques discussed herein.
has applied for a patent on this device.
cell
to handle
program.
demonstrated
considered
and reconditioning.
and
been
and
a battery
reconditioning/protection life
is expected
However,
capacity
Skylab
charge
being
designed
test
of power
redesign.
This
in series.
circuit
for
space
terminate
systems
of cell
manufactured
used
useful
to have
either
requirements.
and
flexibility
requirements
and
placed
to build this
The
or component
a 110 V or higher
10 percent
the
a longer
and are still performing anticipated as a result MSFC
like
selection
using
to have
design
in
discharging
typical
matching
collapse
problem
cells
at MSFC
to only
battery
be expected
cell
electrical
to supply
underway
2 percent
no system
protection
designed
using
reversal.
it to an existing
voltage on the
to be effective
against
with
in high voltage
be matched
approximately any
depending
as additional
a battery
Plans
that
discharge
shown
by completely
can minimize
reconditioning/failure
failures, feasible.
cells
cell
useful
cells
results
to this cell
more
combination
the
been
battery
by connecting
excellent
similar
has
of a Ni-Cd
protecting
achieving
it can
discussed
capacity
demonstrated
of a circuit
because
circuit
for
can
batteries, in low
4-1/2
reductions
years are
Application for a license
to use this invention, if a patent is granted, should be directed to the patent counsel at MSFC.
George
C. Marshall Space National Aeronautics Marshall
Flight and
Space
Center Space Administration
Flight
Center,
Alabama
35812,
April
1977
23
REFERENCES
.
Immamura,
Donovan,
Protectors
for
MCR 76-263, .
Bauer, NASA
24
Paul: Office
Sealed
Lear,
and
Silver-Zinc
September Batteries of Technology
Murray: Cells.
Development Report
No.
of Single NASA
Cell
CR-135054,
1976. for
Space
Power
Utilization,
Systems,
p.
98.
Prepared
for
1968.
NASA-Langley,
!977
