For decades, most automobile electrical systems were 12 Volts. However, manufacturers have started transitioning from 12-volt to 48-volt electrical systems in some models to accommodate increasing power demands.
What Changed
The increase in power requirements was induced by the introduction of more electronic components over the years. An automobile’s 12V electrical system used to have the burden of powering electric fans, lighting, compressor clutches, radios among other things in pre-1990s models.
Today, in addition to all of the above requirements automobiles have:
- Increasingly advanced driver assistance systems.
- Many more power features.
- Communications and roadside assistance services.
- Infotainment systems.
- Networking equipment.
- Start-stop systems.
- Safety features to avoid collisions.
- Driver behavior tracking.
- Increased integration of hybrid propulsion technology.
- In some cases, the use of electric AC compressors.
Why Voltage Matters
12-Volt electrical systems can theoretically deliver large amounts of power. However, the higher electric current requirements of modern features necessitate thicker wires and more expensive high-current circuitry.
Thicker wires are not only more costly, they are heavier and occupy more space in the vehicle. Switching to a higher voltage system reduces the amount of current that each device in said system requires, facilitating the use of thinner, lighter and cheaper wires that generate less heat.
One of the primary drivers behind the adoption of 48-Volt automotive electrical systems is mild-hybrid cars. Mild-hybrid cars use an electric motor to assist the combustion engine when accelerating from a stop.
These motors can consume more than 10 kW of power, which is very costly from an electrical wiring standpoint. The increasing (and already high) cost of copper wire exacerbates the problem further.
10 kW at 12 Volts is 833 Amps of current, while 10 kW at 48 Volts is 208 Amps of current. That means a 48-Volt motor could use significantly smaller wires.
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