24 V vs 48 V for AGV/AMR Drive Systems: How to Choose

Key takeaways

• For the same power, a 48 V system draws half the current of a 24 V system, so cable and connector losses fall to about a quarter and voltage drop to half.
• 24 V suits small, light robots with drive power of a few hundred watts and a large 24 V ecosystem of sensors and controls. Above roughly 400–500 W per wheel, or with a powered lift, 48 V is usually the better traction voltage.
• 48 V stays in the extra-low-voltage range; very heavy vehicles move to 96 V. JY Robot uses 48 V for its drive-steering units (0.4–5 kW), differential modules and lifting modules, and 96 V for the largest configurations.
• Size motors and speeds at the minimum battery voltage and check drive limits at the maximum charging voltage, not at the nominal value.
• Most vehicles end up with both: a 48 V traction bus and a 24 V supply for logic, brakes, sensors and I/O.

1. Why voltage matters: current

Electrical power is voltage times current (P = U × I). Doubling the voltage halves the current for the same power, and almost everything else follows from that:

• Cable and connector losses scale with the square of the current (P = I² × R). Half the current means about a quarter of the loss.
• Voltage drop along cables, fuses and contactors scales with current. Half the current means half the drop, and the drop is also a smaller share of a higher voltage.
• Cable cross-section, connector size, fuses and contactors are chosen for current. A 48 V harness is lighter and easier to route.
• Charging contacts carry the charging current; at 24 V they carry twice as much for the same charging power.

2. Worked example

An AMR needs about 1,350 W from the battery during acceleration (1,080 N at 1 m/s and roughly 80 % drivetrain efficiency, as in our tractive force guide) plus a 1,000 W lifting motor. The battery cable is a 4 m loop of 10 mm² copper (about 6.9 mΩ).

Motor peak currents during acceleration are typically two to three times the rated current, so the differences grow exactly when the vehicle needs the power.

3. Nominal voltage is not the operating voltage

A "48 V" battery is a voltage range. A 16-cell lithium iron phosphate (LiFePO4) pack is nominally 51.2 V, reaches about 58.4 V when fully charged and falls towards 40 V when empty; a "24 V" 8-cell pack spans about 20–29 V. Two checks follow:

• Speed at minimum voltage. A motor's maximum speed falls with supply voltage. Check that the vehicle still reaches its target speed under load near the end of discharge.
• Drive limits at maximum voltage. Drives must accept the full charging voltage plus regenerative braking. JY Robot's integrated servo wheels, for example, take 24–60 VDC drive power, with dynamic braking activating at 63 VDC ±2 V.

4. Safety and standards

Both 24 V and 48 V are extra-low-voltage systems. 48 V also stays below the 60 V DC level that many standards use as the limit for touch-safe circuits in dry conditions, which keeps insulation and protection measures simple. Going to 96 V (used on some heavy vehicles) requires a more careful review of protection against electric shock. In every case, battery energy is the main hazard: short-circuit current, fusing and battery management matter at any voltage. Confirm the requirements of the standards that apply to your vehicle, such as ISO 3691-4 for driverless industrial trucks.

5. When 24 V is the right choice

• Small service, delivery and inspection robots and light AMRs with drive power of a few hundred watts.
• Vehicles whose sensors, controllers, lidar and I/O are all 24 V, so no DC/DC converter is needed.
• Low-cost platforms where existing 24 V hub drives fit, such as JY Robot's 7030/8030 hub drive wheels.

6. When 48 V is the better choice

• Vehicles of several hundred kilograms and above, or drives above roughly 400–500 W per wheel.
• Vehicles with a powered lift; JY Robot's ball screw lifting modules use 200–1,000 W motors at 48 V.
• Higher speeds, frequent acceleration or ramps, where peak currents would be high at 24 V.
• JY Robot's drive-steering units (0.4–3 kW) and differential drive modules (1.0–2.5 kW per wheel) are rated at 48 VDC.

7. When to go above 48 V

Very heavy vehicles need several kilowatts per wheel. At 48 V the currents become large enough to make cables, contactors and charging difficult, so some configurations move to 96 V: in JY Robot's range, the 7.5 kW double-support drive-steering unit and the 20-ton hydraulic lifting differential drive use 96 VDC.

8. Mixed systems are normal

Most AGVs and AMRs combine a traction bus with a 24 V auxiliary supply. JY Robot's 48 V drive-steering units use 24 V brakes, and the integrated servo wheels have a separate 24 VDC logic supply. Plan a DC/DC converter sized for sensors, controllers, brakes and I/O, and keep logic power alive when traction power is cut, so that the controller can report faults and STO or brake states.

9. Decision table

FAQ

Is 48 V more efficient than 24 V for an AGV?

For the same power, a 48 V system draws half the current, so resistive losses in cables, connectors and switching components are about a quarter. Motor and drive efficiency depend more on the specific design than on the voltage.

Can I run a 48 V drive from a 24 V battery?

Usually not at full performance. The motor's maximum speed falls roughly in proportion to voltage and many drives have an undervoltage limit. Check the drive's supply range; JY Robot's integrated servo wheels accept 24–60 VDC, but speed and torque data are given for the rated voltage.

What voltage do heavy AGVs use?

48 V covers most AGVs up to several tons. Very heavy vehicles with several kilowatts per wheel often use 80 V or 96 V to limit current; JY Robot's 20-ton hydraulic lifting differential drive uses 96 V.

Do I still need 24 V on a 48 V vehicle?

Almost always. Brakes, sensors, safety controllers, lidar and I/O are commonly 24 V, so a DC/DC converter from the traction battery is standard.