To diagnose a failed learning cycle, it is critical to set BQStudio to log the data RAM during the cycle every ~5–10 seconds. It is also advisable to auto-export the data flash on a less frequent basis (every ~1–10 minutes). This way, all of the information is collected to determine the point of failure.

Tips for the learning cycle are as follows:

1. Ensure that the battery is at a low SOC and relaxed when running IT_ENABLE. This is typically not a problem, but it is important.
2. During the charge, ensure that the gauge detects the FULL CHARGE condition. If after the learning cycle, Update Status has not been updated to 05 (that is, it is still 04), then this may be the problem. The gauge detects the full charge condition with three criteria:
   1. Battery voltage is within 0.1 V of the Charging Voltage as defined in BQStudio.
   2. Battery current is below Taper Current, as defined in BQStudio.
   3. Battery current stays below this Taper Current and above the Quit Current for over 40 seconds.

   This means that the battery must be charging with a significant current below the Taper Current for almost a minute. If the charger cuts off before or just after the current drops below the Taper Current, as indicated in BQStudio, then the gauge does not detect the "full" condition.

3. When the battery is fully charged, wait long enough for the VOK bit to be cleared. This is generally two hours. Logging data RAM shows if this has occurred. Update Status will stay 04 if this does not happen. If VOK is never set, then this means that it did not start with an empty battery or did not fully charge the battery or the charge cycle was disturbed in some way (see Step 7) for charging information.
4. When discharging starts, ensure that the VOK bit is set. The gauge has the data flash parameter Dsg Threshold that determines the minimum current needed to enter the DISCHARGE state. If it discharges with less than this current, the VOK bit will not be set. The gauge will never go into the DISCHARGE state, and the Ra tables will never be updated. Update Status will be 05. Either decrease Dsg Threshold in the data flash, or increase the discharge rate.
5. During the discharge, the resistance table is never updated. If during a learning cycle the data flash log shows that the resistance table never changed, this indicates that the discharge load was too light. The gauge needs to measure a significant voltage drop across the internal battery impedance before it can measure the impedance. If the load is too light, the measurement fails, and it will never get any resistance table updates.
6. During discharge, the resistance table may update for a while and then stop. When this happens, RUP_DIS is set. This indicates that the Chemistry ID choice is incorrect. This means that the gauge has measured a resistance value that just does not make sense (that is, is negative). A chemistry cycling is needed to identify the correct chemistry profile.
7. General charge/discharge profile information: Most learning cycles fail because there is something incorrect with the charge/discharge profile. The following are suggestions:
   1. Ensure charger cutoff upon charge completion: Most users do not have a battery cycling automation setup, so a bench power supply is used to change a battery overnight. This is not recommended. The system does follow a CC/CV profile, but there is no cutoff. Therefore, when the gauge recognizes a full charge and tries to take an OCV measurement, it actually measures the supply voltage and disrupts the system.
   2. CC/CV charge profile: In line with the above, ensure that a CC/CV profile charger with reasonable values is used: C/2 fast charge rate, C/100 to C/10 taper current.
   3. Continuous charge profile: While not strictly necessary, it is advisable to ensure that the charging profile is continuous. If the charging cycle stops, then the cycle may fail. If the battery discharges for any reason during this time, the cycle will fail.
   4. After charge, relax at least two hours with NO load/charger. Wait long enough to see VOK. Two hours is generally enough.
   5. Discharge C/5 constant current. Use a C/5 current. This is preferred, and there can be some error; however, if the current drifts too high or too low, the cycle can fail. Too low is around C/10; too high is around C/3 to C/2. Smaller cells (<800 mAh) are much less forgiving in this regard.
   6. Continuous discharge: This is absolutely necessary. If the discharge ever stops before reaching the terminate voltage, the cycle will fail.
   7. Termination voltage: Ensure that when terminate voltage is reached, the load is removed. Let the cell relax. If the load stays attached to the battery and causes the battery voltage to drop well below terminate, then not only does the learning cycle fail, but it also damages the battery.
8. If Impedance Track is not enabled (IT_ENABLE = 0), Qmax updates can still occur if a relax period lasts more than 5 hours.