Choosing how to charge an AGV fleet is an engineering decision, not an accessory decision. The right AGV battery charging strategy determines fleet uptime, battery lifetime, robot size and total cost of ownership.
This guide covers the fundamentals fleet engineers need before specifying a charger: battery chemistry, charge cycles, opportunity vs. full charging, and how to size a wireless charging system.
AGV battery charging basics: chemistries and voltages
AGV fleets run on three main chemistries, and the choice shapes everything downstream — cycle life, charge speed, and whether the pack tolerates the short, frequent charges that opportunity charging demands.
| Chemistry | Key characteristics | Best for |
|---|---|---|
| Lead-acid | Inexpensive up front and tolerant of rough handling, but must return to a full charge to prevent sulfation, charges slowly, and delivers only 300–500 cycles under deep-discharge AGV duty. | Single-shift operations that can park overnight. |
| Lithium iron phosphate (LiFePO4) | The modern default: roughly 2,000–4,000 cycles, no memory effect, a flat discharge curve, and full tolerance of frequent partial charges. | New projects, and any fleet that will use opportunity charging. |
| Nickel-manganese-cobalt (NMC) | Higher energy density than LiFePO4, but generally asks for a more conservative charge window to protect cycle life. | Projects where payload weight is the constraint. |
Pack voltage follows the vehicle class:
- 24 V — light AMRs, carts and small carriers.
- 36 V — some middle-weight tuggers.
- 48 V — the workhorse for pallet movers, heavy AGVs and forklift platforms: a higher voltage moves the same power at lower current, shrinking cables, connectors and losses.
Whatever the voltage, the pack is a series stack of cells, so the BMS charge limit — not the charger's label — sets the true ceiling on how fast the battery can accept energy. For a full comparison of chemistries, see our guide to battery types.
Charge cycles: full charging vs. opportunity charging
The two charging models differ in when the vehicle charges, how the pack is treated, and what the fleet gains:
| Full charging | Opportunity charging | |
|---|---|---|
| When it charges | The vehicle runs until its working state of charge is spent, then sits off-line for one controlled charge back to the BMS target at the end of the shift. | Short, automatic top-ups at the natural stops in the workflow, so the pack spends the day in a mid-range state of charge instead of swinging to near-empty and back. |
| Battery impact | Easy on the battery — one thermal cycle and one balancing window per day. | Frequent, shallow cycling that lithium handles well and lead-acid does not. |
| Fleet trade-off | Simple to engineer; the vehicle is out of service for the full charge. | A smaller, cheaper battery, and availability that stays high through peak demand — the price is that charger power, station placement and cycle capability must be engineered for shallow cycling. |
That availability trade-off is the real decision. New AGV projects therefore pair lithium packs with opportunity charging. For the full treatment of availability, station counts and battery-level behavior, see our guide to Opportunity Charging for AGV and AMR Fleets.
How to size a charger for an AGV fleet
Charger sizing starts from energy, not wattage. Three numbers define the problem:
- The battery capacity, in watt-hours.
- The energy the vehicle actually consumes per mission.
- The time the vehicle can spend at a charging point.
The required average power is the energy to be replaced divided by the charging window. Worked example:
| Input | Value |
|---|---|
| Battery pack | 48 V, 200 Ah = 9.6 kWh |
| Energy burned per mission | 1.2 kWh |
| Time at the dock | 10 minutes (0.167 h) |
| Required average power | 1.2 kWh ÷ 0.167 h ≈ 7.2 kW |
Two practical caps sit above that number:
- BMS charge limit — sets the maximum pack current, and therefore the real power ceiling.
- State-of-charge window — a pack cycled between 30% and 80% requires far less energy per session than a full 0–100% cycle.
Size the charger to the recovery window that actually recurs in the route, then confirm the pack and BMS can accept the resulting current continuously. For the full worked method, including voltage, current and C-rate limits, see How to Choose Charging Power for AGV and AMR Batteries.
Wireless AGV charging: how it works
A wireless AGV charger transfers power inductively between two coils: a transmitter pad fixed to the floor or wall, and a receiver coil mounted on the vehicle. The transmitter drives a high-frequency alternating field — typically in the tens-to-hundreds of kilohertz range — and the receiver coil converts the coupled flux back to DC for the battery.
Two mechanical numbers govern the design:
- Air gap — the distance between the coil faces.
- Docking tolerance — the lateral and angular misalignment the system can absorb while holding rated power.
Larger gaps and looser tolerances cost coupling efficiency and coil size, so a realistic docking-accuracy target matters more than peak efficiency on paper. A well-aligned system typically runs at 88–93% efficiency at full power — within a few points of a good conductive connection, and acceptable for opportunity duty.
Because the interface is sealed, there is no exposed metal to corrode, spark or wear. That is why wireless charging is the specified answer in dusty warehouses, wash-down areas, cleanrooms and automated production lines, where a mechanical connector becomes the failure point.
AGV charging station design considerations
Station design begins with placement: put the pad where the vehicle already stops — loading docks, conveyor transfer points, staging zones — so charging time comes free from the workflow instead of costing a detour. The engineering detail follows in two layers:
- Alignment and environment — the pad must sit flat enough that the vehicle's docking accuracy keeps the receiver inside the coil's tolerance zone, and the site must absorb the real conditions — dust ingress, humidity, wash-down, cleanroom particle control, floor joints — which drive the enclosure rating and mounting method.
- Integration — the charger should talk to the vehicle controller or BMS over CAN or RS485, so charging starts and stops on the fleet's schedule rather than on a timer, and fault and status signals reach the fleet management system.
For the complete design methodology, including docking types and safety protection, see our AGV Charging Station Design guide, and for a vehicle-side specification checklist see the AMR Charging Station Specification Guide.
Specifying a charger for your project
Before you request a quote, gather the numbers the design depends on:
- AGV or AMR type
- Battery voltage and capacity
- Charging window available at each stop
- Docking accuracy the vehicle can hold
- Air gap to the receiver
- Operating environment
- Required communication interface
- Target quantity and project timeline
A one-page summary with those fields is enough for our engineering team to shortlist a wireless charging system and check it against your BMS limits. You can request a quote directly from this page with the product preselected — a 3kW system (LS300-A60) — and note your battery voltage and charge window in the form; we will confirm suitability or recommend a different power class.
Working on an AGV or AMR fleet project? Use the quote button below — include your battery voltage and charge window and we will respond within one business day.