Campbell Scientific PS200/CH200 12 V Charging Regulators - Manual (Page 10)

PS200/CH200 12 V Charging Regulators
2. Precautions and Tips
Under normal charging conditions with sealed VRLA batteries, hydrogen and
oxygen gasses are produced in relatively small quantities, most of which later
recombines back into water. Aggressive overcharging produces excess
hydrogen and oxygen gasses, resulting in gas venting by means of a pressure
activated valve. Hydrogen gas emitted from VRLA batteries must not be
allowed to accumulate, as it could form an explosive mixture. Fortunately,
hydrogen gas is difficult to contain in anything but a metal or glass enclosure.
Never put VRLA batteries in an enclosure that does not
allow emitted hydrogen gas to be dispersed. WARNING
VRLA batteries are capable of providing high surge currents. The 12 V output
terminals of the PS200/CH200 are fused with a 4 A self-resettable thermal
fuse, but there is no fusing for inadvertent bridging of the battery terminals.
Accidental shorting of battery terminals by metallic objects, such as
watchbands, can cause severe burns due to rapid heating and is also a fire
hazard.
VRLA battery manufacturers state that “Heat Kills Batteries”. While the
PS200/CH200 can operate from –40°C to +60°C, optimum battery life is
achieved with battery operating temperatures ranging from 5°C to 35°C
i , per
manufacturer’s recommendations 1 . The PS200/CH200 offer temperature
compensation of the battery charging voltage based on a temperature
measurement inside the PS200/CH200 cases. The CH200 internal temperature
measurement likely will not accurately represent battery temperature for charge
voltage compensation unless the battery is in close proximity to the CH200.
The PS200/CH200 serial interface can be used to input an independently
measured battery temperature for improved charging temperature
compensation when the charger temperature is different than the battery
temperature (see Section 6.2.3.1, Write Remote Battery Temperature to
PS200/CH200, and Section 6.2.3.2, Restore Internal Battery Temperature
Measurement, for SDI-12 programming examples and Section 6.3.3.2, Write
Remote Battery Temperature to PS200/CH200, and Section 6.3.3.3, Restore
Internal Battery Temperature Measurement, for RS-232 programming
examples).
With rechargeable batteries, a charge → discharge → re-charge event is termed
a cycle. In general the most important factor for the service life of a battery is
depth of discharge
1 . For example, decreasing the depth of each discharge from
100% to 50% approximately doubles the number of useful cycles available
from the battery
1 .
i Genesis Application Manual – Genesis NP and NPX Series US-NP-AM-002,
June 2006.
2