Cellwatch Frontier - Page 37

Cellwatch Frontier System Installation & User Manual
Section I – Installation Guide-37
 VRLA installation on shelves or small cabinets
 VRLA installation on open racks
 VRLA stacks with front access
 VLA (flooded) cells on open racks
The DCM 5T is necessary for thermal runaway protection on open rack systems due to the temperature
variances across the string. Small cabinet or contained systems are often small enough that a single
ambient probe will suffice in monitoring overall temperature and can adequately detect thermal
runaway conditions.
It is important to identify the type of installation using the outline above. Typically VLA or high amp-hour
VRLA systems will have ohmic values below the 0.5mΩ range. Readings in this range can be impacted by
both tab location and DCM wire dressing. It is always important to properly torque the battery, never to
have stainless steel between the tab washer and the terminal post, and to consider DCM wire lengths
and wire dressing.
The smallest capacity rated container that can be monitored and still meet our DCM specification is
28Ah (ampere hour) per DCM test point.
VRLA shelves in a cabinet, stack, or open racks and VLA in open racks
VRLA batteries can be stored in multiple configurations depending on the make and additives to the
cells. Strings on open racks can be configured in a variety of ways with multiple inter-tier configurations.
Regardless of the physical layout, it is important to identify the number of cells that will be monitored in
this system. Configurations that are easily divisible by four (4 monitoring points) can quickly be tabbed
for DCMs. The tabbing and installation process is replicated for every four cells as shown below. For
systems that are not divisible by four, see the section titled Short strings. For systems where battery
trays are used for easy removal of the cells, see the section titled VRLA installation on four-jar trays.