Battery Technology Comparison
| Battery Type | Full Charge Time | Cycle Life | Runtime vs Lead-Acid | Charging Overhead |
|---|---|---|---|---|
| Lead-Acid | 5+ hours | 300-500 cycles | Baseline | ~30% of work time |
| Pure-Lead AGM | ~30% of work time | Better than standard LA | Similar | ~30% of work time |
| Lithium-Ion / LFP | 2 hours full; 10-20 min opportunity | 4,000-6,000 cycles | 3x | ~10% of cycle time |
| Li-ion with wireless | Same as Li-ion | Same | Same | ~8% of cycle time |
LFP (lithium iron phosphate) is the dominant new-build chemistry. 60% lighter than equivalent lead-acid. ~10x longer cycle life.
Charging Methods
Opportunity Charging (Contact Poles)
- Vehicle charges during idle periods at defined charging stations
- Li-ion: 10-20 minute charge adds several hours of runtime
- Lead-acid: requires near-full discharge first; opportunity charging degrades lead-acid cells
- Traditional contact pole connection (mechanical contact)
Wireless / Inductive Charging
- Contactless power transfer via inductive pad
- Up to 95% energy transfer efficiency
- Enabled by smart battery management system (BMS) with data communication
- Overhead: ~8% of cycle time for Li-ion with wireless
Manual Battery Swap
- Operator swaps depleted pack for charged pack
- Near-continuous vehicle operation (~98% availability)
- Highest labor cost
- No specialized charging station required per vehicle
Automatic Battery Swap
- Robotic system exchanges batteries without human intervention
- Eliminates labor cost of manual swap
- Higher infrastructure investment
Charging Method Selection Logic
| Condition | Recommended Approach |
|---|---|
| High utilization (>80%), Li-ion | Opportunity charging (wireless preferred) |
| High utilization, lead-acid | Manual or automatic swap |
| Low-medium utilization | Opportunity charging at end-of-shift or break |
| 24/7 operations, maximum uptime | Automatic swap or wireless opportunity |
Rule: match charging approach to vehicle utilization rate and available idle time. No universal answer - requires project-specific analysis.
Battery Management System (BMS)
Modern AGV batteries include an integrated BMS that:
- Monitors cell voltage, temperature, and state of charge
- Enables data communication with the fleet management system
- Controls charging current to prevent damage
- Required for wireless charging compatibility
Fleet-Level Power Planning
- Li-ion allows fleet to run on fewer vehicles due to lower charging overhead (10% vs 30%)
- Lead-acid 24/7 fleets typically require 1.3-1.5x the vehicles needed for a single shift to account for charging rotations
- Wireless opportunity charging simplifies lane design (no manual swap station footprint)
- Charging stations must be included in fleet management traffic routing
In-Aisle Busbar Charging (VNA-AGV project spec, Jungheinrich 2024)
Source-derived from vna-agv-site-readiness-specs-dematic-jungheinrich-2024. Very-narrow-aisle AGVs can draw power in-aisle from a busbar rather than cycling an onboard battery, which is what makes automated three-shift VNA operation practical (an AGV cannot manually swap batteries).
- Busbar supplies 3-phase AC, 400 V +/-15%, 50-60 Hz through a current collector into an on-board ZIVAN NG9 HF charger (9 kW, efficiency >87%), which outputs DC to the truck with excess to the battery. Battery variants 80 V or 48 V.
- Closed busbar (contact inside a U-profile: better protection, higher install height) vs open busbar (front-face conductors: lower install height in racking, better access, requires fingersafe contact protection and defined PE placement).
- The current collector compensates horizontal and vertical tolerances and absorbs impact; charger switched by transponder/magnet with delayed on-off to prevent break-spark and contact burning at aisle entry/exit.
- Electrical site-readiness (customer scope, easily missed): per-aisle 35 A 3-phase protection, 30 mA fault-current (RCD) breaker, per-aisle lockable OFF main switch, plus phase and excess-voltage monitoring. Entry guide must be installed before racking; mount busbar as close to the floor as practical to minimize collector lift travel.
[!practitioner-note] The datasheet battery is not the AGV power system A VNA truck’s manual datasheet lists a large lead-acid pack (e.g. Jungheinrich EKX 516: 80 V / 930 Ah, 2,178 kg). The automated version re-architects power around the in-aisle busbar. Do not size the AGV deployment’s energy plan from the manual-truck battery row.