<s>
A	O
reserve	B-Algorithm
battery	I-Algorithm
,	O
also	O
called	O
stand-by	O
battery	O
,	O
is	O
a	O
primary	B-Algorithm
battery	I-Algorithm
where	O
part	O
is	O
isolated	O
until	O
the	O
battery	O
needs	O
to	O
be	O
used	O
.	O
</s>
<s>
When	O
long	O
storage	O
is	O
required	O
,	O
reserve	B-Algorithm
batteries	I-Algorithm
are	O
often	O
used	O
,	O
since	O
the	O
active	O
chemicals	O
of	O
the	O
cell	O
are	O
segregated	O
until	O
needed	O
,	O
thus	O
reducing	O
self-discharge	B-Algorithm
.	O
</s>
<s>
A	O
reserve	B-Algorithm
battery	I-Algorithm
is	O
distinguished	O
from	O
a	O
backup	B-Algorithm
battery	I-Algorithm
,	O
in	O
that	O
a	O
reserve	B-Algorithm
battery	I-Algorithm
is	O
inert	O
until	O
it	O
is	O
activated	O
,	O
while	O
a	O
backup	B-Algorithm
battery	I-Algorithm
is	O
already	O
functional	O
,	O
even	O
if	O
it	O
is	O
not	O
delivering	O
current	O
.	O
</s>
<s>
These	O
batteries	O
are	O
used	O
in	O
radiosondes	O
,	O
missiles	O
,	O
projectile	O
and	O
bomb	B-Device
fuzes	B-Protocol
,	O
and	O
various	O
weapon	O
systems	O
.	O
</s>
<s>
While	O
not	O
advertised	O
as	O
reserve	B-Algorithm
batteries	I-Algorithm
,	O
the	O
principle	O
is	O
illustrated	O
by	O
the	O
sale	O
of	O
"	O
dry	O
charged	O
"	O
car	B-Algorithm
batteries	I-Algorithm
where	O
the	O
electrolyte	O
is	O
added	O
at	O
the	O
time	O
of	O
sale	O
.	O
</s>
<s>
Another	O
example	O
is	O
zinc-air	B-Algorithm
batteries	I-Algorithm
where	O
the	O
cell	O
is	O
sealed	O
until	O
use	O
:	O
a	O
tab	O
is	O
removed	O
to	O
admit	O
air	O
and	O
activate	O
the	O
cell	O
.	O
</s>
<s>
Reserve	B-Algorithm
batteries	I-Algorithm
may	O
be	O
activated	O
by	O
addition	O
of	O
water	O
,	O
by	O
adding	O
electrolyte	O
,	O
by	O
introducing	O
a	O
gas	O
into	O
the	O
cell	O
that	O
is	O
either	O
the	O
active	O
cathode	O
material	O
or	O
part	O
of	O
the	O
electrolyte	O
,	O
or	O
by	O
heating	O
a	O
solid	O
electrolyte	O
to	O
a	O
temperature	O
at	O
which	O
it	O
becomes	O
conductive	O
.	O
</s>
<s>
A	O
molten-electrolyte	B-Architecture
battery	I-Architecture
is	O
activated	O
by	O
igniting	O
a	O
pyrotechnic	O
heat	O
source	O
.	O
</s>
<s>
The	O
battery	O
delivers	O
current	O
for	O
a	O
short	O
time	O
(	O
seconds	O
to	O
a	O
few	O
minutes	O
)	O
,	O
but	O
some	O
thermal	B-Architecture
batteries	I-Architecture
can	O
be	O
stored	O
ten	O
years	O
or	O
more	O
without	O
deterioration	O
.	O
</s>
<s>
Reserve	B-Algorithm
batteries	I-Algorithm
remain	O
uncommon	O
in	O
civilian	O
applications	O
because	O
of	O
their	O
higher	O
cost	O
and	O
relatively	O
short	O
life	O
after	O
activation	O
.	O
</s>
<s>
In	O
missiles	O
,	O
reserve	B-Algorithm
batteries	I-Algorithm
typically	O
use	O
a	O
small	O
container	O
of	O
pressurized	O
air	O
to	O
force	O
the	O
electrolyte	O
from	O
a	O
storage	O
tank	O
into	O
the	O
battery	O
.	O
</s>
<s>
Some	O
reserve	B-Algorithm
batteries	I-Algorithm
are	O
:	O
</s>
<s>
Thermal	B-Architecture
battery	I-Architecture
,	O
a	O
class	O
of	O
battery	B-Algorithm
types	I-Algorithm
with	O
molten	O
salt	O
as	O
an	O
electrolyte	O
.	O
</s>
<s>
Common	O
in	O
military	O
applications	O
,	O
especially	O
for	O
missiles	O
and	O
proximity	O
fuzes	B-Protocol
.	O
</s>
<s>
Water-activated	B-Algorithm
battery	I-Algorithm
,	O
a	O
class	O
of	O
batteries	O
where	O
the	O
electrolyte	O
is	O
water	O
that	O
has	O
to	O
be	O
added	O
,	O
such	O
as	O
HydroPak	O
or	O
NoPoPo	B-Algorithm
.	O
</s>
