User Manual for the Type 8370
WSM 6+ Transponder
UM-8370
Issue A Rev 1
Section 3 – Technical Description
10
3.9 Battery and Charger
3.9.1 Type
The WSM 6+ is fitted with a 2000 mAh nickel metal hydride battery pack and must only be charged
with the Sonardyne Type 8370-011-01 (/-02 ) comms/charger unit and matching charger PSU.
Earlier types of transponder have different battery pack capacity, different rating AC power packs
and different versions of charger are not compatible with the WSM 6+.
3.9.2 Charging Description
A flat battery will charge for approximately 3 hours at the full rate of 1 A, during which the red Fast
Charge LED will illuminate. The charging current is applied to pin 3 of the external connector (zero
volts is pin 2). This charge time is considerably longer than the one-hour charge of the SSM. This is
due to the use of higher capacity NiMH cells in the WSM 6+, which cannot be charged at such a
high rate as the lower capacity cells in the SSM.
The charging current is controlled by electronics inside the transponder. When the battery reaches a
full charge the charging current is switched off, and the Fast Charge LED will switch off. However,
the charger also permanently supplies external power to the unit (28 V, 85 mA on pin 4) which will
trickle charge the unit and illuminate the yellow Trickle Charge LED. It is safe to leave the trickle
charge connected indefinitely.
3.9.3 Fast Charging Feature
The Fast Charge feature is controlled by electronics inside the transponder which monitors the
voltage and temperature of the battery pack to decide when to stop charging. The parameters are
first monitored some 14 minutes after connection so connecting the fast charger to a fully charged
battery will allow the full charging current to flow for that length of time.
Repeatedly connecting the fast charger to a fully charged (or near fully charged) battery will reduce
the life of the battery and may cause damage.
The charge control chip within the transponder will cut off charge current if:
•
The rate of change of voltage with time indicates the pack is approaching full charge.
•
The temperature of the pack rises outside limits (10–40ºC).
•
A time limit is exceeded (in the WSM 6+ case this is three hours).
The current during fast charging is limited by the WSM 6+ PSU, not by the WSM 6+ charger/comms
unit.
If, in an emergency, it is necessary to charge the WSM 6+ by means other than the Type 8370-011-
01/02 dedicated comms/charger unit, then the charge supply should be 24 V at 1A constant current
for 2 hours maximum.
Note
The charging time must be reduced if the battery pack has been charged recently. The charging
current should be applied to pin 3 of the external connector with the return (zero volts) connected to
pin 2.
