BP-2 EV Battery Pack Line — Module Station Isolation
Maintenance at a module stacking and busbar welding station on an EV battery pack line. Covers the packs themselves, which arrive charged and cannot be de-energised, alongside the laser welder, station power and the gas detection that stays live.
How Setyr addresses Automotive andManufacturing →
It refers to equipment that does not exist and illustrates the elements 29 CFR 1910.147(c)(4)(ii) requires a procedure to contain. It is not a document to adopt. Under (c)(4)(i) the employer must develop and document energy control procedures specific to their own machines, and under (c)(6) must inspect them at least annually.
12 points, in sequence
Battery modules present at the station. Nominal 400V pack, cells arrive at partial state of charge.
Method: Modules CANNOT be isolated. Remove all modules from the station and place them in the quarantine rack before work begins, or treat the station as live.
Caution: A charged lithium module has no off switch. There is no disconnect, no bleed, and no state in which it is safe to short. Removing it from the work area is the only control.
Manual service disconnect on any partially assembled pack remaining at the station.
Method: Remove the MSD, retain it under personal control, and allow the pack capacitors to discharge before touching busbars.
Caution: Removing the MSD splits the pack but does not discharge the halves. Each half remains at hazardous voltage.
Station 480V main disconnect feeding the stacker, welder and conveyor.
Method: Open, lock, prove dead at the load side.
Caution: Station isolation does nothing to the energy stored in the modules on the line.
Laser welder supply and beam shutter interlock.
Method: Open and lock the welder supply. Confirm the beam shutter is closed and the key is under personal control.
Caution: A class 4 beam is invisible and reflects off busbar. Interlocks are defeated for setup more often than anyone records.
Welder capacitor bank in the laser power supply cabinet.
Method: Allow the capacitor bank to discharge for the full time, then confirm below threshold with a meter and apply the grounding hook.
Caution: The grounding hook is applied after the meter reading, not instead of it.
Module handling robot servo power at the station.
Method: Open and lock servo power. Confirm the robot brakes hold with power removed.
Caution: Servo brakes fail to applied, but a robot holding a module overhead is relying on those brakes.
Mechanical arrest pin on the robot axis carrying load over the station.
Method: Insert the axis arrest pin. Must be ENGAGED.
Caution: Brake failure with a module in the gripper drops it into the work area. The pin is the backup.
Station pneumatic supply to clamps, lifts and the pack fixture.
Method: Close and lock the supply, then bleed the station air header to zero.
Caution: Clamps release on loss of air on this fixture, which drops the pack rather than holding it. Bleed only with the pack removed.
Glycol coolant fill and leak-test connection to the pack cooling plate.
Method: Close and lock both fill and return valves.
Caution: Coolant onto exposed busbar creates a conductive path across cells that cannot be switched off.
Station fume extraction over the weld area.
Method: Do NOT isolate. Confirm extraction is running.
Caution: Welding fume and, in a thermal event, vented electrolyte both leave through this system.
Electrolyte vapour and hydrogen detection at the station and over the quarantine rack.
Method: Do NOT isolate. Confirm detection is in service before work begins.
Caution: A module in thermal runaway vents before it burns. Detection is the warning that lets people leave.
Station fire suppression sized for a lithium event, and the quarantine rack immersion bin.
Method: Do NOT isolate. Confirm suppression is in service and the immersion bin is filled and accessible.
Caution: A lithium fire is not put out by a standard extinguisher. The bin is the plan.
What your site must supply
This example is structurally complete and factually generic. The things below are the things only you can know — and they are exactly what makes a procedure yours.
- Your own asset and isolation-point tag numbers. The tags shown are illustrative and refer to equipment that does not exist.
- The actual location of every disconnect, valve and vent on your equipment.
- Measured stored-energy magnitudes and the dwell time required to dissipate them.
- Your verification method for each point, and who is authorised to perform it.
- Any additional energy sources present on your equipment and absent here.
Author this properly, once
Setyr holds procedures like this as living documents — bound to real isolation points, with lock registries, group lockout, person-in-charge custody and periodic review built in.