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Feature 5 | ENERGY GENERATION & STORAGE
submarine.
as underwater, or in aviation applications,
having a strong mechanical design, long
Submarine autonomy gain with Li-Ion technology
cycling life, high efficiency, and offer easy
70%
paralleling of cells. )
Compared to lead acid technology,
l
e
a
d

(
%
60%
y

50%
Li-ion modules are capable of high d

t
o
r
e
o
l
og
40%
levels of current discharge and, for a
pa
30%
submarine, the available energy will
m
t
e
c
hn
20%
be practically the same, says Saft, from
a
i
n

c
o
a
c
i
d

10%
low speed to high speed, noting that the
G
0%
mechanical design of the Li-ion cells is 246810
such that they can withstand a shock, Speed (Knots)
such as from a mine, of 320g 3ms,
without damage. Submarine autonomy gain with Li-Ion technology.
The high-energy VL45E cells can be
cycled more than 4000 times at 80%
Others operational advantages are:
 the reduction of the noise signature due to the removal of auxiliaries system attached to the lead acid battery
incremental depth of discharge with a 20%
(
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udies
oling sys
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and v
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ilatio
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b
ow
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e.
type equipped with Li-ion
loss of energy, equivalent to 3200 times ensure The knowledge of the capacity that any submarine bstatus is better thattery using an thbe aletatder acy id ibs attmeryo. rIt e detphenadn s o75% nly on tahet vlooltw ages lpeveeel odf
the nameplate capacity over life, while the
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i

-
c
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lls
n

technology could not react in and 200% at high speed. The charge
high-power cells can be cycled more than this way. efficiency of the Li-ion technology
420,000 times at 3% incremental depth The conclusion of these studies is that is greater than lead acid batteries,
of discharge with a 20% loss of power the battery system should be redundant, and the maximum intensity of the
(equivalent to 12,600 times the nameplate with two batteries installed in two charge is greater, and due to these
capacity over life). dedicated compartments. “The risk of two characteristics, the submarine’s
“A submarine in operation for 15 years fire inside the compartment is limited. indiscretion ratio can be enhanced.
will cycle the batteries between 1000 and Battery compartments are tight and fire Integration of Li-ion batteries enables
3500 times depending on number and insulated to protect batteries,” notes Saft, more fuel oil to be carried, due to the fact
type of missions, depth of discharge and and battery compartments are equipped that the volume of battery compartments
battery size, so we can expect to have at with temperature monitoring systems, can be reduced, and this increase in fuel
least 80% of full installed energy after 15 fire detection and extinguishing systems. oil capacity and the better indiscretion
years of operations,” states Saft. The Li-ion cell has also been tested in rate significantly enhances the autonomy
Naval modules consisting of 40 representative submarine environmental of the submarine.
cells that were tested at different rates conditions (such as shock), and no failures Other operational advantages include
showed that, on a three hour charge and have occurred. a reduction in the submarine’s acoustic
discharge cycle the energy efficiency was For the submarine application, modules signature, due to the removal of auxiliary
96%, a level of performances that will are connected in parallel, and groups of systems attached to the lead acid battery
significantly improve the indiscretion modules are connected in series to achieve (cooling system, electrolyte agitation
ratio of a submarine. the voltage level required of the network. compressor) and reduced ventilation
Due to the reduced size of the module flow; and more accurate estimation
Integration and the modularity concept, the battery’s of capacity.
Another advantage of the Li-ion architecture can easily be adapted. For “Li Ion technology is now ready to be
technology is that gas is not released the Scorpène submarine, 108 groups are used as the main batteries on submarines,”
in operation, and there is no risk of connected in series. says Saft. “Tests have been carried out to
explosion due to the hydrogen produced Concluding the paper
S
,
a
Sa
fe L
f
it
t
hium
hig
ion
h
n
lig
aval
h
en
ts
er

gy sto
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ag
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k
yst
t
e
h
ms
a
a
t
n
t
d
h
ap
e
pl
L
ica
i-io
tion
n module is complian
12
t
/13
by a lead acid battery, thus providing a the fact that submerged aut
o
o
n
n
bo
o
ar
m
d Sc
y
orp
i
e
s
n

e con
w
ve
i
n
t
ti
h
on

al
t
s
h
ub
e
m

ar
r
in
e
e
quirements of submarine
high level of safety. The cells are tight, so, increased, due to the high energy density integration, and the feasibility of integrating
compared to lead acid technology, there of the Li-ion technology. With Li-ion Li-ion batteries on a Scorpène submarine
are no limitations in terms of plate-form technology it is also possible – unlike demonstrated. Li-Ion technology
attitude such as trim and heel, and no risk a lead acid battery – to proceed full allows submarine performance to
of leakage of the electrolyte. charge at sea. With the Li-ion batteries, be enhanced in a number of ways,
Li-ion cells can release hot gases if they “capacity measurement is easier and including better submerged endurance,
incur damage, if the cell overheats for any can be made with more confidence, and a better indiscretion ratio, and greater
reason, such as because of excess external we can expect to use 95% of nominal level of autonomy, and safety and
temperatures (due to fire, for example); capacity at sea”. maintainability onboard are improved
an over-charge; or over-current (such as This being the case, the improvement (no hydrogen and no electrolyte filling
due to an internal short circuit), so safety of the dived autonomy of a Scorpène required). WT
38 Warship Technology January 2009
WT_Jan09_p36+37+38.indd 38 12/23/08 2:26:03 AM
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