Reader asks about battery voltage

The 12-volt battery used in a Lexus NX 300h hybrid electric vehicle is located in the rear area under the floor. James Halderman photo
The 12-volt battery used in a Lexus NX 300h hybrid electric vehicle is located in the rear area under the floor. James Halderman photo

Wheels:

Paul of Bellbrook writes by email: “Always enjoy your comments to readers. Here’s a topic I never see discussed that I’ve been pondering for several years. Back in the 1950s cars transitioned from a 6-volt standard to a 12-volt and after 60-plus years it’s still that way. Shouldn’t we be at a higher voltage now, say 24, 36, 48 or even higher? Or is 12 the optimum? Or is it so entrenched that no one dares to suggest an upgrade? Seems to me that a higher voltage would be more efficient. Your thoughts?”

Halderman:

You are correct that the 12-volt standard has been around since the 1950s. You are also correct that a higher voltage would result in less current (amperes) used by the electrical accessories and components which in turn would require smaller gauge wires.

There was an effort several years ago to have a dual voltage system using 12 volts and 42 volts, but it never became popular with vehicle manufacturers. Now instead of increasing the voltage, the use of light-emitting diodes (LEDs) for lighting has greatly reduced the electrical load which is now handled easily using 12 volts.

Now vehicle manufacturers are starting to electrify their vehicles, and some are using 48 volts to help propel the vehicle (anything less than 60 volts is considered to not represent a shock hazard).

These mild- or micro-hybrid vehicles are a lower-cost version of the more expensive full-hybrid vehicles that use higher voltage. These higher voltages of about 300 volts do represent a shock hazard, and the wiring is covered with orange conduit to help warn people of the potential danger.

Full-hybrid and full-electric vehicles that are propelled using battery power alone also use a 12-volt battery for all the lighting and accessories. These 12-volt batteries are often in the trunk areas and hidden behind panels.

Have an automotive question? Get a straight answer by writing to Jim at jim@jameshalderman.com.

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