Preparing the published article.
Opportunity Charging vs Battery Swap: Fields to Record First
How to compare opportunity charging and battery swap using idle-window data, charge-event records, and a written charging rule.
Map the Duty Cycle Before You Choose a Charging Model
Charging is a scheduling problem before it is a hardware choice. Extract from your task records the windows when each vehicle is idle for more than a few minutes, grouped by hour of shift, and add the state of charge at the start and end of each window. Opportunity charging suits work that produces many short idle windows near a charger; battery swap suits long uninterrupted runs where a vehicle cannot leave the route cheaply. Record the reasoning, not only the conclusion.
Then record the physical facts at every candidate charging point: distance from the busiest aisle, walking time for an operator, whether a vehicle can reach it without crossing a traffic lane, whether it blocks a fire route or an exit, and whether the floor and the electrical supply can carry the equipment your risk assessment requires.
- Per charging point: location name, distance to the busiest pick face, crossing traffic lanes, floor loading limits.
- Infrastructure: supply capacity, isolation point, ventilation, and who is permitted to connect a vehicle.
- Access rules: can an operator connect a vehicle, or is it a technician task, and during which shifts.
- Housekeeping: cable routing, floor markings, and where a spare pack or adapter is stored.
Ask the site health and safety lead to sign the list of charging locations before installation, because retrofitting a vented, isolated charging room after commissioning costs far more than choosing the location correctly once.
Record Every Charge Event During the Trial
Run a logging period of at least two weeks and capture one row per charge event: vehicle ID, charger ID, start time, end time, state of charge at start and end, energy delivered if the charger reports it, who initiated the session, and whether the vehicle left before reaching the target state of charge. Those rows answer questions a specification sheet cannot.
Record failed or aborted sessions separately, with a cause: connector not seated, charger fault, vehicle fault, operator interrupted the session, or the vehicle was called away. A charger that is busy during peak is a scheduling problem; a charger that faults is a maintenance problem, and the two need different fixes.
- Utilisation: charger busy hours, idle hours, and the longest queue observed at peak.
- Energy: units delivered per shift, and the cost basis your finance team uses per unit.
- Reliability: sessions that ended below target, and the state of charge reached instead.
- Manual work: minutes per session spent by an operator connecting, disconnecting, or moving a vehicle.
If swap is under consideration, log the same way at the swap station: swap duration from arrival to release, number of people involved, tools or lifting equipment used, and where spare packs are stored. Measure the queue at the busiest hour; a swap that takes only minutes per vehicle still fails if three vehicles arrive together.
Turn the Records Into a Written Charging Rule
Write the result as a one-page rule that an operator can follow without asking a supervisor. State which vehicles may use which chargers, the state of charge at which a vehicle must be released during peak, who may interrupt a charging session, and what a driver should do when a charger is occupied or faulted.
Give the rule an owner and a review date. Charging behaviour drifts when shifts change, when the task mix changes, or when new vehicles join the fleet, and a rule without a review date quietly stops matching the operation.
- Thresholds: the state of charge at which a vehicle must leave a charger, and who set that value.
- Escalation: the first person to call when a charger is down, and the temporary workaround allowed.
- Records: where the charging log lives, who reads it weekly, and which fields trigger action.
- Change control: how a new charging location or vehicle is added to the rule, and who approves it.
Finally, compare the trial records against the duty cycle you mapped in week one. If vehicles are charging more often than the idle-window analysis predicted, the task mix, route lengths, or load weights have changed, and the charging plan should be revised rather than left to run.
Photo credits: the images in this article are licensed reference photographs of the relevant robot class, credited with author and licence in each caption; they are not photographs of the specific equipment discussed. Licence and author details are recorded with each image.