Cellwatch Frontier System Installation & User Manual
Section I – Installation Guide-41
nulled channels on one of the DCMs, or a single channel on two DCMs. In the example below, channel 4
is nulled, meaning that the Green, Blue, and White wires would terminate on the same post.
16V 16V 16V
DCM
+
-
Three-jar tray example nulling 4
th
channel
Note: Always start nulling from channel 4 first, then channel 3, and finally channel 2.
Considerations for high ampere-hour, low ohmic value VLA and VRLA
Any errors or variances introduced in ohmic value measurements can easily mislead the user in these
configurations. In particular, it is recommended to:
1. Ensure tab washers are as close to the terminal post as possible (as described previously).
2. Ensure that there is no material between the tab washer and the terminal.
3. Do not install the DCM to the metal frame of the rack/stack.
4. Use a small amount of non-corrosive battery grease on the tab washers to reduce the possibility
of corrosion. Conductive silver-loaded silicon grease can also be used.
5. Consider eliminating the inter-tier straps if they are not monitored individually.
6. Landing both power and sense leads on the same ring tab contact point will increase resistance
readings. Best practice is to keep sense leads on a separate ring tab than the power leads.
If measuring stacked, front terminated, bussed batteries, take great care to balance the channel
measurements through tab washer location. This can be done by keeping all sense tabs on the same side
of the cell.
Considerations for cells with four or more posts
Some installations, typically in open rack or stack configurations, may have more than one positive and
negative post per cell. If there is more than one positive post, it is recommended to terminate the
brown and white wires on the same post and the red and blue wires on the same post. This removes
offsets that could be caused by current flowing through a tab washer providing a more accurate reading.
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