Choosing how to charge an automated guided vehicle (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: how AGV battery systems are put together, the chemistry and voltage choices inside them, charge cycles, opportunity vs. full charging, and how to size a wireless charging system.
AGV battery systems: chemistry, voltage and capacity
An AGV battery system is the vehicle-side assembly that stores and manages energy: the cell pack, the battery management system (BMS) that protects and balances it, and the charge interface the vehicle exposes to a charger. All three are specified together, because each one constrains the others.
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 — middle-weight platforms and automated tugger trains.
- 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.
Automated tugger trains deserve their own note, because they break the voltage pattern. A tractor unit pulling several loaded carts draws far more energy than its 24 V or 36 V class suggests, and the load changes with every trip — an empty return leg costs a fraction of a loaded one. Size the battery system on the worst realistic train and route rather than the average, or the vehicle will finish the shift short.
Capacity is the third variable, and it is usually set by the charging strategy rather than by shift length. A fleet running opportunity charging can specify a smaller, lighter pack, because the vehicle never has to carry a full shift of energy — it only has to bridge the gap between stops. A fleet charging once per shift needs a pack sized for the whole shift plus reserve.
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, and for the charger side of the same question, see which batteries a wireless charging system can charge.
AGV battery charging systems: the three parts
An AGV battery charging system is not a single product. It is three parts that have to be sized against each other:
- The charger — the unit that converts site power into the current and voltage the pack accepts, whether that is a conventional charger on a cable or a wireless transmitter driving a coil.
- The battery — the pack and its BMS, which set the real ceiling on accepted current and the voltage window the charger has to follow.
- The charging point — where the vehicle physically connects or parks: a bay, a dock, or a floor pad at a stop the vehicle already makes.
Most specification problems come from treating those as three separate purchases. A charger chosen on its label power, a battery chosen on capacity, and a charging point placed wherever there happened to be room will not necessarily work together. The battery's BMS current limit can cap a charger well below its rating, and a pad in the wrong position costs more in detour time than a higher-power charger ever saves.
So the specification runs backwards from what most teams expect. Start with the energy the vehicle has to recover and the time it can spend charging, derive the required current, check that current against the pack's BMS limit, and only then choose a charger and place the charging point. The charging power guide works through that calculation, and the sizing section below applies it to a worked example.
For the charger itself, the practical choice is between a cable connection and a wireless charging system — covered later on this page.
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.