MAX17201 tracks the battery age in calendar time, and cycles age. This data is periodically saved to NV memory. During production, the manufacturer could choose to lock the NV memory to prevent it from being updated again over the I2C interface.
When the NV memory is locked, MAX17201 can still update its own learned parameters when the cycles register exceeds the ncycles (last non volatile backup) by a configurable threshold called cyclespsave. Because the threshold is used to only increase the cycles register, a battery refurbisher can't attempt to reduce the cycle count and save the data to NV memory. This prevents anyone from reducing the cycle count to use a potentially failing, or aged battery in an application where battery failure could lead to catastrophic results.
The cyclespsave configuration in the nNVCfg1 register should be selected to last the age of the battery in cycles. The chip can update its learned parameters 200 times. If a battery is designed to run only 1000 cycles, the cyclespsave should be set to 5 cycles to save as frequently as possible.
In addition, with the life logging function in the MAX17201, all previous values of cycles, age, full capacity, and any other parameters learned by the battery can be read back to confirm that no tampering has happened. See the “Life Logging” function in the datasheet for examples and details.