The physics: same power, half the current
Power is voltage times current. An 800 W motor draws about 65-70 A at 12V but only 33-35 A at 24V. That current flows through cables, connections and the contactor: halving it cuts cable losses and contact heating to a quarter, since they grow with the square of the current, and greatly reduces the likelihood of electrical failure, the number one cause of service calls on DC units.
| Aspect | 12V | 24V |
|---|---|---|
| Current of an 800 W motor | about 65-70 A | about 33-35 A |
| Effect of a 1 V cable drop | nearly 10% of the supply | about 4% of the supply |
| Cables and contactor | large cable cross-sections, more stressed contacts | more forgiving installation |
| Where it is used | vehicles with a 12V system: trailers, light vehicles | trucks, agricultural machines, frequent cycles, above 2 kW |
Cables and voltage drop
At 12V every metre of cable matters: a 1-volt drop is nearly 10% of the supply, and the motor pays for it in torque and heat. Rule of thumb: cables as short and as thick as practical, clean tight connections, ground straight to the chassis. At 24V the same installation is far more forgiving.
When is 12V mandatory and when does 24V pay off?
If the only battery available is the vehicle’s 12V one, the choice is made for you: converting is almost never worth it. 24V pays off on trucks and agricultural machines (which already carry it), with frequent cycles and at power ratings above 2 kW, where 12V currents become hard to manage. In between, the duty cycle decides: ask us to size it for you, free of charge.