Racal Instruments RT695A User manual

RT695A - PRC-41
Manpack UHF transceiver
1963
Either the battery or the ac power supply can be attached to the RT695.
Both have the same size (28 x 10.5 x 19 cm) and weight ( 7.5 kg)
The battery must be charged with a special charger, not this PP-3700
Battery
BB-451/ U
Receiver-Transmitter
RT-695 / PRC-41
size 28 x 10.5 x 35 cm
weight 10,5 kg
Power Supply
PP-3700

PRC-41 REFERENCE DATA
a. POWER REQUIREMENTS. - 26.5 volts dc+10 percent (equipment will operate with an input voltage as
low as 22 volts dc)or 115 or 230 volts ±10 percent, 50-to-400-cps single phase.
Equipment is normally connected for 115 volts; cable re-fabrication is required for operation from a 230-volt
source. Refer to section 2 of Installation and Operation Technical Manual for Radio Set AN/PRC-41.
Alternatively, battery BB-451/U is used for 10 hours with 1 minute transmit / 9 minutes receive cycle.
b. FREQUENCY DATA.
(1) Range: 225.0 to 399.9 mc.
(2) Channels: 1750 spaced at 100-kc intervals over the range.
(3) Stability: ±15 kc.
(4) Type of frequency control: Crystal.
(5) Number of crystals: 39 crystals.
(6) Type of transmission and reception: A3.
c TRANSMITTER DATA.
(l) Power output: 3 watts average unmodulated power into a 50-ohm load.
(2) Modulation: AM.
(3) Modulation sensitivity: Carbon microphone input of 1.0 volt.
(4) Modulation capability: 80 percent minimum (adjusted to clip between 70 to 90 percent).
(5) Transmitter fidelity: +1, -3 db, 300 to 3500 cps (from 1000-cps reference).
(6) Transmitter distortion: Less than 10 percent with modulation 3 db below clipping level.
(7) Duty cycle: 1-minute transmit, 9-minute receive.
d RECEIVER DATA.
(1) Sensitivity: A signal having an average level of 3 uv modulated 30 percent at 1000 cps produces 7 mw at a signalplus-
noise to noise ratio of 10 db or greater.
(2) Selectivity: 6 db, 47 kc minimum; 60 db. 120 kc maximum.
(3) Images and spurious responses: 70 db
(4) I-f rejection: 80 db down.
(5) Avc characteristics: Output within ±3 db from 10 to 100,000 uv (from 1000-microvolt reference).
(6) Blocking: No blocking for input signals up to, 0.5 volt.
(7) Squelch operation: A change in audio output of at least 10 db is effected by a l-db change in input signal.
(8) Ultimate S+N/N ratio: At least 35 db (measured at 1000 uv).
(9) Audio output: 50 mw into a 300-ohm load with 30- percent modulation, 1000 uv.
(10) Audio fidelity: +1, -3 db from 300 to 3500 cps (from 1000-cps reference).
(11) Audio distortion: Less than 10 percent at 50-mw output.
e. GUARD RECEIVER DATA.
(1) Sensitivity: A signal having an average level of 5 uv into the guard receiver modulated 30 percent at 1000 cps
produces 7 mw at a signal plus-noise to noise ratio of 10 db or greater.
(2) Selectivity: 6 db, 50 kc minimum; 60 db, 200 kc maximum.
(3) Images and spurious responses: 60 db down.
(4) I-f rejection: 80 db down.
(5) Avc characteristics: Output within ±3 db from 10 to 100,000 uv (from 1000-microvolt reference).
(6) Blocking: No blocking for input signals up to 0.5 volt.
(7) Squelch operation: A change in audio output of at least 10 db is effected by a 1-db change in input si gnal.
(8) Ultimate S+N/N ratio: At least 35 db (measured at 1000 uv).
(9) Audio output: 50 mw into a 300-ohm load with 30-percent modulation, 1000 uv.
(10) Audio fidelity: +1, -3 db from 300 to 3500 cps (from 1000-cps reference).
(11) Audio distortion: Less than 10 percent at 50-mw output (1000-microvolt input, 1000 cps, 30-percent modulated).
Battery - BB-451/U 24V - 25Ah Nominal, rechargeable battery
The battery consists of 16 series-connected silver-zinc cells constructed in blocks of four cells each. Nominal open-circuit
voltage of a fully charged cell is 1.86 volts per cell. The minimum voltage per cell under specified load is 1.375 volts at -11
°C (+12F) and above, and 1.250 volts from -10°C to -25°C (+14F to -13°F).
The battery cells will perform according to specifications after charging at a modified constant current of 2.5 amperes
average with voltage cutoff at 2.03 volts. Emergency charging of the cells is possible by charging at a constant potential of
2.03 volts per cell with charge acceptance as follows: a 0.5- charge period replaces 50 percent of the capacity removed on
previous discharge; a 4-hour charge period replaces 60 percent of the capacity removed on the previous discharge.
All recharging must be with Battery Charger PP-3240/U or its exact replacement.. A plastic sheet for recording charging
history is bonded to the underside of the cover plate. To avoid a long formation and activation period. the BB-451/U is
supplied in a dry charge condition.

The PRC-41 is a portable transceiver for ground-to-air service, built with modified modules
from the ARC-51. It is intended for forward air control.
The radio has 1750 channels in the military 225-400 MHz band, spaced 100kHz.
Output power is approx. 2W ( 3W max). The unit is supplied by 26Vdc, at 2A in receive, or
2.8A in transmit , plus a short (7ms/ 2A ) pulse for the coax T/R switch when changing from
Rx to Tx or back.
Components:
Transceiver RT 695 / PRC-41 28 x 10.5 x 35 cm , 10.5 kg
Power Supply PP-3700 28 x 10.5 x 19 cm , 7.5 kg
Battery BB-451/U 28 x 10.5 x 19 cm , 7.5 kg
Transceiver Like the ARC51, The RT695 is a triple superhet with fully crystal controlled
channels. Differences to the ARC51 are: Manual control, no crystal oven, simplified squelch
circuits and only 2W RF output.
Versions: The RT695A has a slightly modified audio circuit to allow voice encryption using
the external crypto unit KY-38
Battery The battery has 16 silver/ zinc oxide cells, filled with potassium hydroxide (KOH).
The nominal voltage and capacity is 24V, 25Ah, although it was recommended not to
discharge beyond 20Ah.
With a cycle of 1 minute transmit and 9 minutes receive, the battery will last 12 hours at an
ambient temperature between –20 and +35 deg. C.
The battery can be recharged up to 20 times with 16 x 2.03 = 32.5V, initially current limited
to 2.5A. After 20 recharge cycles, the battery is discarded, and the silver is recycled if
possible.
AC Power Supply The PP-3700 is a transformer-ballast type power supply with 26.5V
output at maximal 4.5A, in the same case as the battery.
The PP-3700 is not physical nor electrical suitable to recharge the battery.

Interconnections between modules and power supply
B,V,H,T,P
PRC-41 INTERNAL WIRING
3 - 3- 2018 / kb
RFI filters not shown
1
1H /57Ω
3
µ
F
2
µ
F
4x
1N649
39
Q1 .
2N1486
Q2 .
2N1486
6,9
800 Hz
POWER SUPPLY
MODULE
+6.3V
6442
7554
7554
7077
+12.6V
+18.9V
1
8
16
17
Spectrum generator
RF Amplifier
6.8V, 10W
1N2970
100
HEATERS
K6 2x
25R
0.93A
4A
33uF
+26.5 V
Q1 .
2N1486
1N
1358
16 cells 25 Ah
Silver-zinc alkaline
1.86V fully charged
1.30V end of discharge
33uF
+20V
TEL
MIC
3d IF
First &
2nd IF
15
8
2
9
C
D
D
3
5
1
Guard
3
9
6
7
6
10
1
2
1mH / 1
Ω
A
Tx
relay
s
Rx
+
180V
Push
to talk
39
1k2
1k2
3
-6.8V
1N159
15
µ
F
5
7077
7554
7554
7077
1,2,3,6
7077
+180V
+180
Mod
4
7,9
26
V
6
10
MODULATOR
K3
K1
MIC
AUDIO
6
2
7
1
5
4
4
5
8
IN
OUT
1mH/ 1Ω
K4
0.5Ω
OFF
TR/G
+24.5
T/R
6
3
19
15
-
6.8
20
9
coax T/R
switch
3
K4
3
K3
K1
7
11
K3
K1
Auto
relay
12
squelch
50k
K4
9
5
470k
1
6
4
3
7
2
5
8
LIGHT
100
+av
5
14
470k
390
0.68u
0.47u
150
A2
A1
A3
20p
39p
to KY38
13
J1
J2
J3
1N916
B
H
F
+26.5 V
L
U
R
agc
+24
no agc
Remote on/off
J
25
filter
stud
BB-451/U
7
VOL
10
19 pole crypto plug
10 pole headset plug
both on front
J
C
S
N
A
K
K5
J
J
16
140mA
1A

Module circuit diagrams
PRC 41 AUDIO
21 nov 2017 kb
4
5
3
330
T2
T1
1k 5k6
4k7
+24.5V
9
3
100
470
47u
2
1
15uF
47u
3k3
50mH
2k7
15k
10k
220
5
4
2
6
2k2
guard
main
15k
33k
10k
10k
2u2
1uH
22uF
22uF
Q2 .
2N1481
Q1 .
2N338
Q3,Q4 .
2N656
56nF
J2
1k
50 mW into a
300-Ωload
is 11Vpp min
20Vpp into 300Ω
measured
1
7
+19V
3.5mA
+
8V
+
4V
+
1V
35mA
10k
VOL
10Ω
2x 18Ω
2x 1k2
106Ω18Ω
PRC 41 MODULATOR
18 jan 2018 kb
4
5
4
5
3
47
430
mike bias
T2
T1
To RF
PWR
AMPL
Z=3k
100
1k
820
6k8
2k7
side
tone
+180V
+26.5V on Xmit
3
7
2
8
+24.5V on Xmit
carbon
mike
input
8.2
10nF
150k 15k
820
47
56u
2
1
5.6u
Q1 .
2N1486
Q1,Q3
2N1486
160Ω
2x 5Ω
2x 180Ω
36 Ω
1
3
4
5
J2
J1
9
52 mA bias
1Vpp in for
300Vpp out
320Vpp clip
10Vac
330
Class B
10nF
+26 V
out
1
6
5
9
mike
1
6
5
9
main
in
guard
in
out
+26 V
J1

coax T/R switch
470k
390 0.68u
0.47u
150
20p
39p
1N916
K1
First LO (A5 ) 200 - 370 MHz in 18 steps of 10 MHz
RF AMPLIFIER ( A8 )
To 3d IF (500kHz)
First & second IF
A2
2nd LO
17-26 MHz
PRC-41 RF parts
For heaters see power supplies sheet
9 dec 2017 kb
A1
A3
A2
V1
7077
V4
7554 V5
6442
V4
7554
V3
7554
V2
7077
V1
7077
1st LO
100
82
J2
150
10
33
+180V
17k
220k
680
330 680
J2
All relay contacts
shown in receive position
J9
-
J10
J3
J1
J2
J7
J1
J1
225-400 MHz
First IF
20-30 MHz
Z1
Z4
Z5
1 : 2
+13dBm
( 1Vrms)
470 p
2
2
470p
500
6p
4
20
20
2 2 20
2
22k
0.22
10p
Testpoint, 1M series resistor and
500pF feedtru not shown
51
10k
100
V2
7077
Z2
2
470 p
10
V3
7554
470
+190V
Z3
2
20 p
500 p
100
82
1k8 2k7
J3
J4
500 p
470
J5
J6
330 680
20p
9
2N1481
A1
19
-6.8V
to guard receiver
+26V
coax relay
3d LO
2.9-3.8 MHz
15k
470
A1
+190V
4k7 4k7 modulator
6
15
14
13
4 spare
1N251
4
J8
J11
0.7V
0.7V 1.7V 1.0 V
-2 V-2 V
45mA
@Tx
+133V
+125V (Rx) / 190V (Tx)
No oven
100k
0.1V without signal
225 - 400 MC
Bandpass filter
+26V on Tx
4k7
10k
2k2
10u
5
20
+24V
-AVC
12Ω
K1

PRC-41 First and second IF amplifier ( A2)
3 nov 2017 kb
15k
22k
1k
100
470
6k8
1k
220
2k7
10k
2k7
1k
15k
15k
4k7
1k8
12
100k
100p
100p
1k8
15k
4k7
4k7
J1
J3
J2
120
1k
2k7
100k
33k
1k5
1k
4k7
1k
4k7
39k
3k3
100k
7p
5 6
K2
K1
K3
Q2
2N915
Q1
3N35
Q3
3N35
Q4
3N35
Q6
2N338
Q7
2N338
Q5
3N35
3d LO
2nd LO
1st IF
20-30MHz
A1
A3
A2
500kHz output
Signal to third IF
2nd IF filter
2.9 – 3.9 MHz
17.1 19.1 21.1
18.1 20.1 MHz
26.1 24.1 22.1
25.1 23.1 MHz
2.9 3.1 3.3
3.0 3.2 MHz
3.8 3.6 3.4
3.7 3.5 MHz
10n
10n
1n
10nF
43p
4k7
Tx
+25V 30mA
AVC
A3
A2
A1
1
6
5
10
+25V / 30mA
100p
100p
1n
K2
K1
K3
Coils 26V /40mA
1Vpp RF
1Vpp RF
17.1 MHz
26.1 MHz
29.1 MHz
2.95 MHz
Clockwise= higher freq
Red= 2 unused positions
3d LO & IF
1st IF
2nd LO
20 MHz
3
22pF
1k
20pF
6p
6p
180p
150p
220p
2.7uH
1
nF
47pF
5 pF
K1
1n
1n
+12V
10n
10n
10n
1 pF
7pF
10
10n
1
10
10
1
8p
20p
180p
10k
10k
100p
20p
10nF
10k
10nF
1n
1n
+ AVC

RT-695A / PRC-41 Guard Receiver (A7)
28 feb 2018 kb
1k
15k
22k
3k3
4k7
1k
15k
22k
3k3
4k7
1k
15k
22k
3k3
4k7
1k
15k
12k
3k3
4k7
1k
15k
22k
3k3
4k7
+19V
+19V
+19V
+6.2V
J2
J1
-1.85V
20.56 MHz
243 MHz
Q1
2N917
Q3
2N918
Q5
3N35
Q6
3N35
Q7
3N35
Q8
3N35
Q9
3N35
Q2
2N918
Q4
2N917
1k
1k
1k5
10k 10k 22k
2k2
2k2
2k2
1N231
1N616
Q11
2N329
Q10
2N916
Q12
2N718
1N753A
6.2V
1N753A
10k
220R
R52
100k
12k
2k2
10k
10k
1k8
4k7
Q14
2N697
1k
2k7
1k
R46
Audio
output
9
+27V / 50mA
input
6
Tuneable from 239 – 248 MHz
222.44 MHz
111.22 MHz
doubler
2k2
33
1N3027
3
22uF
1k
150k 10k
2.2u
4.7u
47p
1500p
2p
0.5p
2p 0.33
.33
1N457
47
1n
10n
18p 18p 18p 18p 18p
10k
squelch
10k
220R
R53
2.2u
1nF
10uF
12k
12k
82k
15
k
2k2
1uF
0.1uF
10k
Q15
2N329
Q13
2N706
4k7
4k7
10n
180p
1N751A
20p
2p
6p 4k7
3k3
10n10n 10n
+26 V
1
6
7
10
out
10p
27p
15k
AGC
10n
100k
4k7
+6.2V

PRC-41 3d IF AMPLIFIER
feb 2018 / kb
+
AVC
1k8
2k7
4k7
12k 220
12k
4k7
6k8
6k8
3k3
68k
10k
2.2uF
270
1k
1k
Q1
3N35 Q2
3N35
Q3
2N2219 Q4
2N161
3
Q6
2N2905
500kHz
2k7
15k
1N483
8k2
10uF
+15V
1n
220p
1n
220p
0.5mH
4k7
4k7
2k7
1mH
1mH
100
560
560
Input
24.5Vdc
4k7
2.2uF
4.7uF
NOISE
LIMITER
CONTROL
10k 20k
2u2
2u2
2u2
2k2
100k
220
150
12k
Q5
2N2219
Q10
2N2905
Q9
2N1613
Aux audio
auto relay
reserved for
squelch
disable
Q7
2N2905
+24.5V on Rx
- AVC
DELAY
5k
4k7
1k5
-6.8V
-AVC
SQUELCH
3k3
5k
100
°C K1
K1
1uF
Audio
1k
13
1
4
3
7
11
12
8
15
5
1
6
J1
22k
0.1uF
10uH
50k
82k

PP3700 mains power supply for PRC-41
PP3700 Mains Power Supply
Replaces the battery (has same size and weight)
MT 2976 Vehicle Power Supply
A
4// 0.56 Ω
5//
1500 uF- 50V
1 uF
1 uF
1N 250B
14 uH
B
C
P1
P2
P3
To RT695
PRC-41
From vehicle
battery
660uF
60V
A
F
B
G
E
C
D
115V
1.6AT
45V
115V
1.6AT
3k3
39k
33uF
1k
5k6
33
V
1k
560
15
15
68
68
330
820
26.5V / 4A
Q3 .
2N2113
Q2 .
2N1896
Q1 .
2N1893
48V
Q4 .
2N
697
33k
47
33V
15V
33uF
K1
K1
K1
3x
680
27k
4k7
470
P1
P2
P3
A
C
B
100u
100u
100u
80mH/ 5A
2x 33uF
75V
3
8V
48V average
60V peak
4
7
V
2
8V
1k
2x 4.2Ω
0.4 Ω
1N249
5
8V
To
RT695
PRC-41

Front side connectors
The left connector is for the headset with a standard 10-way NATO plug.
The microphone is normally floating. Pushing the push-to-talk switch grounds one side of the
microphone.
The same connector can also be used for remote turn-on of the complete set , or a small cable
can be connected to a second PRC41 to create a relay station in order to bridge a larger distance
than possible with one set.
The basic PRC-41 has two of these 10-way connectors, all pins are connected in parallel.
The PRC-41Aonly has one 10-way connector. The other one is a 19-way connector
which connects to a Nestor KY38 speech scrambler. Added are two Collins "opamps" in the
RT695A/PRC-41A
A
B
C
E
F
G H
J
K
L
M
N
P
R
S T
U
V
D
26k
68k
10k
aux
audio
guard Rx
output
to C and
D
tel. plug
to H
tel. plug
(ptt)
+26.5 V
to K
tel. plug
(auto relay)
to A
tel. plug
(tel)
to J tel. plug
(remote-on)
10nF
26k
68k
1
2
3
4
5
+26.5 V
opamps: COLLINS 350-011-010
10uF
4
5
3
A
B
C
J
K
F
A
B
C
J
K
F
Relay stations
interconnect cable

Antenna filter
in the PRC-41
BAND PASS FILTER 225 - 400 MC
PN 241 - 0467 - 00
model 5364
BIRD ELECTRONIC CORP.
CLEVELAND, OHIO
0 100 200 300 400 500 600 MHz
dB
-0
-10
-20
-30
-40
-50
-
6
0
antenna Rx / Tx
SMA
mini
BNC

BB-451 /U
TM-11-6140-208-15
SECTION 1 GENERAL DESCRIPTION AND SPECIFICATION DATA
1-1 INTRODUCTION
a. SCOPE. This manual covers the operation, maintenance and repair of the BB-451/U Silver-
Zinc Storage Battery, F8N 6140-889-1027.
b. PURPOSE. The purpose of the BB-451/U Silver-Zinc Storage Battery is to provide a light-
weight power source for use with man-pack communications and electronic equipment. The silver-
zinc battery is superior to the lead-acid, nickel cadmium, and silver-cadmium batteries in watt-hour
capacity per-pound of battery weight. The silver-zinc battery is also superior to the lead-acid battery
in voltage regulation during discharge. The construction, maintenance and personnel precautions
pertaining to the silver-zinc battery vary greatly from the more familiar lead-acid battery. This
manual provides adequate operational and maintenance data on the BB-451/U Silver-Zinc Storage
Battery to ensure proper use, thus minimizing the probability of injury to the user or damage to the
battery.
1-2 PHYSICALAND FUNCTIONAL DESCRIPTION (see Figures 1-1 to 1-3 and Table 1-1)
a. PHYSICAL DESCHIPTION. The BB-451/U Storage Battery Is a rechargeable, SILVER-ZINC,
ALKALINE ELECTROLYTE battery, rated at 25 ampere-hours (AH).
The battery contains 16 series-connected cells with a nominal cell voltage of 1.5 volts, producing a
total nominal battery voltage of 24 volts. Each group of four cells is combined within separate plastic
cases called mono-blocks. A battery, therefore, contains four monoblocks. Each cell within a
monoblock case consists of eight silver (positive electrodes) and eight zinc (negative electrodes) plates.
Each plate is enclosed within several layers of cellulose material. The monoblock casings are made of
molded plastic, and the four cells within the monoblock are equipped with threaded-screw nylon vent
caps. Each monoblock is replaceable as an assembly.
All metal parts of the battery are passivated and nickel or silver plated to resist reaction with the
electrolyte.
The overall physical size of the BB-451/U is 7-11/16 inches_high, 11-9/16 Inches long and 4-9/64
Inches wide. The battery weighs 16 pounds when filled with electrolyte.
Overall Dimensions (Inches) 7- 11/16 H x
11- 9/16 L
.......................................... x 4- 9/64 W
Weight Filled (Pounds) . 16lbs (7.3kg)
Cathode .......................... Zinc
Anode ................ ,............ Silver Oxide
Electrolyte.......... 40% Potassium Hydroxide- KOH
Nominal Cell Voltage..... 1,5 V
Nominal Battery Voltage. 24 V
Nominal Arnpere-Hour Capacity 25 Ah
Open Circuit Voltage....... 29.76 V
Watt- Hour/Pound............ 59
Watt-Hour/Cubic Inches.. 4. 4
Voltage Regulation .......... Good
Discharge Rate (Maximum, Amperes) 25 A
Cycle Life (Cycles) ...... 10-30
The input current of the RT695A / PRC41 is 1.9A in receive mode, or 3.1A in transmit mode.

b. FUNCTIONAL DESCRIPTION.
The battery when charged, has positive electrodes of silver oxide and negative electrodes of metallic
zinc. During discharge the positive plates are reduced to silver while the negative plates are Oxidized
to zinc-oxide. Charging the battery reverses this process (returns It to the charged state). The
electrolyte acts as a medium for the exchange of Oxygen, and is also the current carrier within the cell.
In an alkaline cell, unlike a lead-acid cell, the electrolyte does not take part in the chemical trans-
formations. Therefore, its specific gravity does not change with state of charge of the cell. This
then, makes a hydrometer useless with the BB-451/U Silver-Zinc Storage Battery.
(1) Intended Use. The BB-451/U is designed to provide a lightweight power source to meet the high-
current demands for man-pack radios such as the AN/PRC-41 and the AN/ PRC-47.
(2) Limitations. The following limitations apply to this battery.
(a) Heavy Discharge Sensi tivity. Even though the BB-451/U is rated at 25 AH at 24 volts dc for radio
receiving and transmitting applications, it is recommended that it not be discharged more than 20 AH
per cycle, since a deeper discharge will materially shorten the battery life.
(b) Low Temperature Sensitivity. The performance of the battery is seriously affected by low tem-
peratures. At temperatures below approximately -35°C (-31°F) the battery effectively ceases to
operate
(c) High Temperature Sensltivlty. The performance of the battery la seriously affected by very
high temperatures. At temperatures above 100°F (37.8°C). the cycle life and wet life are greatly
reduced (see Table 1-2.).
(c) Sensitivity to OverFilling. Both the silver and zinc plates of the battery are soluble in the
electrolyte, therefore, the instructions on filling should be carefully followed (see paragraph 1-4
"Servicing").
(d) Sensitivity to OverCharging. The battery will not accept excessive current during overcharge,
but rather, this current will cause the generation of hydrogen and oxygen, and will be of no aid to
charging the battery.
WARNING
THE BB-451/U IS A SILVER-ZINC BATTERY UTILIZING AN ALKALINE ELECTROLYTE
OF 40% POTASSIUM HYDROXIDE (KOH). DO NOT INSERT SULFURIC ACID (H
2
SO
4
) USED IN
LEAD-ACID BATTERIES, AS ACID WILL REACT VIOLENTLY WITH THE ALKALINE
ELECTROLYTE CAUSING PERMANENT DAMAGE TO THE BATTERY AND POSSIBLE
INJURY TO THE USER
TABLE 1-2. BATTERY PERFORMANCE AT VARIOUS
TEMPERATURES
Temp (°F> Cycle Life* Wet Life (Months )**
-13 20 12
0
20
12
32
25
12
40
30
16
75
30
18
90
25
18
10
0
20
12
120
10
2
140 10 1
* Cycle Life: The number of charge/discharge cycles the battery
experiences.
'* Wet Life: Useful life of activated battery.