Rechargeable NiCd batteries
By default, the FS-5000 radio station is powered by
two large rechargeable batteries
that are both installed at the front left of the set.
Although the radio station could also be powered by the PSU, battery operation
was often mandatory. This is why the PSU-connector of the transmitter was
often blocked by a plastic shield. The PSU was then used for charging the
The image on the right shows a typical pair of batteries as they were supplied
with each FS-5000. Sometimes a spare set was supplied, so that one pair could
be used to power the radio, whilst the other pair was
In order to protect against short-circuits, each battery is protected by
a 10A slow-blow fuse that is located at the top. Nevertheless, a current of
10 Amps can cause serious damage to your equipment. Always be careful when
connecting the batteries. A spare fuse is stored in
a plastic compartment at the front side of each battery.
As part of normal battery maintenance, NiCd batteries have to be discharged
and re-charged regularly in order to avoide the so-called Memory Effect
(see below). Furthermore, NiCd batteries should never be fully discharged
(deep discharge) as this could permanently damage them.
Once the batteries have been used and are exhausted, they should be further
discharged using the supplied Slow Dischargers
Marked with the letter 'S'). These are part of the Toolkit.
The slow dischargers have a green LED
that shows that discharging is in progress. Once the LED is off, the battery
is fully discharged. A special circuit inside the slow discharger, protects
the battery against deep discharge.
Next, the batteries should be fully charged before they
can be used with the FS-5000 again.
Note that NiCd batteries should always be charged when they are stored
for a longer period of time. This is necessary to avoid a deep-discharge
as a result of the batteries natural self-discharge. It is good practice
to always discharge and charge the batteries after use.
Due to the nature of NiCd batteries, they might suffer from the so-called
Storage Effect, also known as the Battery Effect. The effect
is seen with batteries that have not been fully discharged before they are
charged again, and with batteries that have been charged too long.
The result is a battery that 'thinks' it is full, causing the charger to
terminate before the battery is really full.
In this situation that battery gets a large internal resistance or
Ri, that increases with each new charge job.
Although the voltage is correct, it collapses as soon as a load is
Batteries suffering from the Memory Effect can be 'repaired' by a
repeated process of fast discharging and recharging, to the point where the
battery is fully charged again and the Ri is decreased to a reasonable
For this purpose, a special dummy load
is supplied with each FS-5000 station.
The image on the right shows the dummy load or Fast Discharger.
Once connected to a battery
suffering from the efect, the
green LED on top of the fast discharger
is lit as long as discharging is in progress. If the battery is in a bad state,
this will usually not take very long. A special circuit inside the discharger
protects the battery against deep discharge. The nominal voltage of the
battery is 14.4V.
When the battery voltage drops below 12V,
the fast discharger turns itself off and will not become active again until
it has been disconnected.
Once the LED is off, leave some time for the battery to cool down (if necessary)
and recharge it using the supplied battery charger (PSU). Once it is full,
connect the fast discharger again and wait for the battery to be fully
discharged. Repeat the above procudure a number of times until the battery
shows normal behaviour again.
There are two ways to charge the batteries. The default method is by charging
them whilst they are installed as part of a
complete radio station. Charging is started by
pressing one of the charge buttons on the charger,
which is part of the PSU-assembly. The FAST-button allows a battery to be
charged in approx. 1 hour. Fast charging should only be used when in a hurry.
For normal charging, the button 10-HRS should be used. This will fully
charge the batteries in approx. 10 hours. Slow charging is always better for
the batteries and will extend their life.
The best way to treat the batteries is to charge them separately, away from
the radio station. This can be done by using the PSU/Charger in combination
with the H-bar as shown in the image on the right.
If a spare set of batteries is available, one set can be used to power
the FS-5000 whilst the other pair is being charged.
This is the recommended mode of operation.
As the battery charger also contains a power-inverter, it is possible to
charge the FS-5000 batteries from any 12V DC source, such as a car battery.
The external 12V source should be connected to the black (-) and red (+)
terminals of the charger.
➤ More about the charger
The NiCd cells used with the FS-5000 had many disadvantages, such as
memory-effect, self-discharge, bad impulse-response and
short shelf-life. However, at the time the FS-5000 was developed (1985),
alternatives were not available and NiCd was the only practical solution.
In later years, better battery cells and new technologies became
available and alternatives were sought for the vulnerable NiCd cells.
One possible solution is the double-size battery shown on the right.
It contains 2 x 6 LiMnO2-cells by Hoppecke (model LSC 3460M),
enough to produce 16.8V and a capacity of no less than 20Ah.
It has a built-in self-restoring fuse, fits in the same space as the two
standard NiCd batteries and can be locked in place as usual.
It has only one connection to the radio. The unit shown here is probably
It is uncertain whether this type of battery was actually taken into
production. LiMnO2 batteries have the disadvantage that they
can not be recharged and need to be discarded after use. The solution
presented here would therefore be rather expensive.
Furthermore, no stocks of such batteries have been found to date.
If you have one or more, please let us know
In 1994, the successor of the FS-5000, called the
HRM-7000, was introduced
with the German Bundeswehr (Army). As it was designed for field
operations, it made use of the purpose-built BPU-7000 discardable
LiMnO2 battery, that is shown in the image on the right.
As this battery was produced in large quantities, it was adapted for use
in combination with the FS-5000M, by means of a special cable.
➤ More information
Each battery consists of 12 NiCd cells with a nominal voltage of 1.2V
and a capacity of 1.1Ah. This gives a total voltage of 14.4V.
As the radio is normally used with two batteries in parallel,
the total capacity is 2.2Ah,
which is enough for ½ hour of constant transmission.
As the DSU transmits its messages as a very short burst of approx. 0.8 seconds,
the batteries will last long enough for a full mission.
Each battery has a special D-type connector with two large pins:
The two large pins are used for + (B) and - (A). Some of the smaller
pins are used for monitoring the battery during charging. Two lines
are used for a temperature-sensitive resistor (PTC) and one line
is used to measure the ½ voltage. The circuit diagram is as follows:
The ½ voltage line (4) allows the battery charger to detect bad cells.
With a good battery, this voltage should be half the nominal voltage.
Quite often, when the quality of a battery deteriorates, a single
cell dies first, causing the voltage in the middle to rise or to drop.
This would then cause the LED marked 'BAD' on the battery charger to be lit.
The PTC is used to detect battery overheating whilst charging.
It is enclosed in a silicone mold that fits nicely between the cells.
The PTC has a nominal value
of approx. 970 Ohm at ambient temperature (20°C),
which rises if the temperature increases, and eventually triggers an alarm.
As most of the FS-5000 batteries were manufactured in the late 1980s,
they are likely to be dead after all this time. Even when it seems
possible to charge them, they may in fact already have started leaking
The image on the right shows what can happen inside an old battery.
The one shown here was manufactured in November 1987. Click the image for
a closer look. Some of the battery's components have leaked-out, causing
a chemical reaction that results in a build-up of toxic crystalline structures
The best thing to do under these circumstances, is to remove the battery cells
and clean the case thoroughly.
Once this is done, it should be relatively
easy to replace the cells with modern alternatives.
Although it seems tempting to replace the old NiCd-cells with modern
Li-ION or LiPo batteries, this might not be a good idea, as such cells need
a completely different power and charge management.
It would probably be best to replace them with NiMh-cells, as they have the
same cell-voltage (1.2V), behave similar to NiCd-cells and are less sensitive
- Battery type: high-charge-current NiCd cells
- Manufacturer: Sanyo Cadnica
- Model: N-1200SCR
- Number of cells: 12
- Voltage per cell: 1.25V
- Capacity: 1.1Ah
- Max. current: 10A
- Fuse: 10A, 250V, slow-blow (T)
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