Humanoid and Quadruped Charging

docks · battery swap · induction · scheduling

A humanoid carries about 2 kWh, so even a large fleet draws little power. The hard problem is uptime, which is why the leaders are moving to self-swapped batteries and charging while standing.

Battery per robot: Tesla Optimus 2.3 kWh, Unitree H1 0.86 kWh, Boston Dynamics Spot 0.61 kWh; a Tesla Model Y Long Range pack holds about 75 kWh. Illustrative hours of work per 24-hour day for a robot with a 4-hour pack: docking with a 2-hour recharge gives 16 hours of work, a 1-hour fast charge gives 19.2 hours, and a 3-minute autonomous battery swap gives 23.7 hours. BATTERY PER ROBOT, kWh Tesla Optimus 2.3 kWh Unitree H1 0.86 kWh Boston Dynamics Spot 0.61 kWh For scale: a Model Y Long Range pack holds about 75 kWh. HOURS OF WORK PER DAY WITH A 4-HOUR PACK (ILLUSTRATIVE) Dock, 2 h recharge 16.0 h working Dock, 1 h fast charge 19.2 h working Self-swap, 3 min 23.7 h working working charging or walking to a dock
Optimus pack
2.3 kWh
Figure 03 pad
2 kW
Atlas, Walker S2 swap
~3 min
Hub
Charging

Finding

Humanoid charging is an uptime problem, not a power problem: 100 robots charging at once draw less than one truck charger, but a robot that docks for two hours every four loses a third of the day

Tesla's Optimus carries a 2.3 kWh pack; Figure 03 charges at 2 kW through coils in its feet while standing on a pad; UBTech's Walker S2 and Boston Dynamics' production Atlas swap their own batteries in about three minutes. At 2 kW each, 100 robots draw 200 kW, a sixth of one 1.2 MW Megacharger stall.

Three replenishment designs are competing. Conductive self-docking is the default for Agility's Digit, Boston Dynamics' Spot (Spot Dock), ANYbotics' ANYmal and DEEP Robotics' X30, and works when the robot has natural idle windows. Inductive pads, as on Figure 03, turn parking into charging, so a robot tops up at its station between tasks without precise plug alignment. Autonomous battery swap, shipped by UBTech (Walker S2) and Boston Dynamics (Atlas) and offered as a staff-swapped pack by Apptronik (Apollo) and Unitree, keeps a robot working around the clock at the cost of spare-pack inventory and a charging rack.

The site design follows from the choice. Dock networks need many small docks near work cells, door transition points between indoor and outdoor zones, and a scheduler that weighs battery state against task urgency. Swap networks concentrate energy in a pack room: dozens of 2 kWh packs on chargers hold more than 100 kWh of lithium-ion, enough that fire officials may review the room like a small stationary battery under NFPA 855. Chinese plants are the largest early fleets, with UBTech Walker S robots at BYD, Zeekr and Foxconn sites; in the US, Tesla runs Optimus at Giga Texas and Fremont, and Agility's Digit works at GXO warehouses.

Robots

How the leading robots recharge

Battery figures where the maker has published them; others left blank.

Humanoid and quadruped replenishment
RobotMaker (base)BatteryReplenishmentStatus, late 2026
OptimusTesla (US)2.3 kWhCharging dockInternal use at Tesla plants
Figure 03Figure AI (US)-Inductive charging through the feet, 2 kWPilots, including BMW Spartanburg
DigitAgility Robotics (US)-Autonomous docking stationPaid deployments at GXO
Atlas (production)Boston Dynamics, Hyundai (US, Korea)-Swaps its own battery in about 3 minutesProduction from 2026 for Hyundai plants
ApolloApptronik (US)-Swappable battery packPilots with Mercedes-Benz and GXO
Walker S2UBTech (China)-Autonomous hot swap in about 3 minutesFactory deployments at BYD, Zeekr, Foxconn
H1, G1Unitree (China)H1: 864 WhQuick-release pack, swapped by staffResearch, education, pilots
SpotBoston Dynamics (US)605 WhSpot Dock self-chargingIndustrial inspection fleets
ANYmalANYbotics (Switzerland)-Autonomous docking stationPlant and offshore inspection; explosion-proof version
X30DEEP Robotics (China)-Autonomous docking stationSubstation and tunnel inspection in China

Methods

Replenishment methods compared

Robot replenishment methods
MethodHow it worksUptimeSite costBest fit
Conductive self-dockingRobot backs onto contacts on a wall or floor dockLowest; idle while chargingLow per dock; many docks neededInspection rounds, single-shift work
Inductive padCoils in the feet or base couple to a floor padHigh if pads sit at work stationsModerate; no plug wearStation-based factory and logistics tasks
Autonomous battery swapRobot removes and inserts its own pack at a rackNear continuousSpare packs plus a charging rackMulti-shift production lines
Manual battery swapStaff exchange quick-release packsHigh, but needs laborSpare packs; staff timePilots and small fleets

Dock types

Where docks go

Dock types for legged robot fleets
Dock typePlacementUseDesign issue
Wall dockCorridors, back-of-house, service roomsLow-footprint indoor rechargeMust not block egress or aisles
Floor dock or padWork cells, warehouse edgesTop-ups during repetitive tasksAlignment tolerance; floor markings or fiducials
Outdoor shelter dockPerimeters, yards, loading areasSecurity and inspection patrolsWeather sealing; secure communications
Swap rackBattery room near the lineMulti-shift humanoid fleetsFire separation, ventilation, pack tracking
Service dockMaintenance baysCharging plus diagnostics, updates, cleaningLong dwell without blocking fast-turn docks

Sources

Sources and scope

Scope
Humanoid and Quadruped Charging
Sources
Tesla (AI Day 2022); Figure AI (Figure 03, 2025); Boston Dynamics (Atlas, CES 2026; Spot specifications); UBTech (Walker S2, 2025); Unitree; Agility Robotics; Apptronik; NFPA 855
Updated
October 2026