A dead battery and lost zero data are one problem in two bodies: the first is the cause, the second the bill. This page writes out our working standard, including the detail most often got wrong - the swap happens with power on.
Absolute encoders hold position memory on the battery across power-off. Most models require the swap with main or control power still on; power down and pull the pack and the memory is gone on the spot. Our order: confirm control power on - verify pack polarity and part number - swap - re-check voltage - record each axis position value. Two people: one swaps, one checks polarity.
Path one, precision master with fixtures: best accuracy, needs a stop and the fixtures - the standard route. Path two, coarse restore from mechanical datum marks or factory indices: gets the machine moving again while a precision master is booked - for lines that cannot wait. Path three, restore from history: when the customer kept calibration data or program backups, restore straight from them at the lowest cost. We recommend by production urgency and write into the record which path was taken and why.
Mastering success is not mastering correctness. Two checks: repeat-positioning on a fixed reference (we run 10 passes and take the spread); spot-check 3-5 of the customer's live production points. Out of tolerance means re-examine the datum itself - an axis whose reducer was replaced may have a shifted mechanical zero mark, and that needs the datum re-established, not the master repeated.
Packs are designed for two to three years and hot cabinets shorten that. Battery voltage is a fixed item on every one of our services; below threshold we replace without waiting for an alarm. That single habit removes most of the "stopped line for mastering" incidents.
