- The current limits may be hitting 0A. For the Charger Safety relay and the Charge Enable relay this means that the charge current limit (CCL) might be hitting 0A causing the relay to latch OFF. For the Discharge Enable relay this means the discharge current limit (DCL) might be hitting 0A causing the relay to latch OFF.
- The maximum current limits may be getting exceeded if Enforce Current Limit is enabled for the relay in question. If the “Enforce Relay Current Limits” option is enabled for the relay, the relay will turn off if the average current being discharged (or charged, for charger safety and charge enable relays) exceeds the discharge current limit. This can be confusing because the current limit for the relay may still be reading a positive number even though the corresponding relay output turns off.
Resolving the issue:
Step 1. Plot the battery pack current and the current limits on the Live Graphing section of the utility to see if the limit is being reduced to 0A when the relay turns off.
If this is the case, then the BMS is turning off the relay output to protect the battery pack.
Step 2. Check to see if the “Enforce Relay Current Limit” option for the relay is enabled on the “Relays” section of the battery profile settings.
If this option is not enabled then this would not be the cause of the problem.
Step 3. If the “Enforce Relay Current Limit” option is enabled, plot the battery pack current and the current limits on the Live Graphing section of the utility to see if they are being exceeded when the relay turns off.
If the relays turn off when the current exceeds the current limit then this is likely the cause of the problem. The problem can either be resolved by increasing the current limits (NOTE: verify that the cells can handle increased current limits) or by reducing the current flow in the application.
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