In the early 1900s, virtually all of the world’s cars and trucks had 6 Volt electrical systems. In the 1950s, most automotive system voltages were bumped up to 12 Volts, and today there is talk of 48 Volt systems.
Why is it that the system voltage in automobiles keeps increasing, and is it likely to keep increasing? Let’s take a look.
What A Car Battery Does
In order to understand the whole voltage thing, we need to know what the different parts of a cars electrical system do. For starter, the car’s main battery helps the driver start the car. Once your engine is running, the power for all the car’s electrical systems is supplied by the alternator, explaining why you can jump-start a car with a dead battery. That is, once you get the engine started in a car with a dead battery, the alternator takes over and provides power to everything.
Car batteries are designed to release a high burst of current to start your car and then be recharged. Typically, the starting process discharges less than three percent of the battery capacity under “ideal conditions.” The extra 97% capacity is for “non-ideal” conditions, such as when its cold out or a light has been left on and the battery is almost discharged.
Car batteries also acts as voltage stabilizers, evening out potentially damaging voltage spikes that can occur when accessories are turned on and off.
Transition From 6 To 12 Volts
In the early days of automobiles, electrical systems were 6 Volt. At the time, engines were low compression (easier to crank over) and had few electrical accessories. 6 Volt systems worked just fine and prevailed for over 50 years, nut things changed in the 1950s, when luxuries like power windows, power seats, power antennas, radios, and air conditioning started to appear. Engineers needed an electrical system that could power all these added features.
General Motors was quick to act, addressing the problem of “more power” by offering the first 12 Volt system in 1954 in the Cadillac Series 62 models. The competition quickly followed suit and, within a few years, every passenger car and truck made in the US had a 12 Volt electrical system.
Consumer couldn’t be happier with the more powerful system. According to the car geeks at Reedman-Toll Chrysler of Springfield, a local Chrysler, Jeep, Dodge, Ram dealer in Springfield, PA, vehicles with 12 Volt systems were simply better — they started faster and allowed multiple accessories like the radio and AC to be used at the same time.
Even More Is Needed
The industry has found itself at another transition point. Today’s cars offer a buffet of new technology, with even car engines, which traditionally used little electrical power, now boasting many electrically-powered components (power steering, power cams, power water pumps, etc). So, wouldn’t a simple solution be to just beef up the existing 12 Volt system? Maybe with larger alternators and more batteries? Let’s do a little math and see if that will work.
Take all the power consumed by all the electrical accessories in a new car — the power windows, the defroster, the heated seats, etc. — and the total will probably be between some 1.5 and 2.0 kilowatts of required power. Let’s assume that future models will need some 3.0 kilowatts of power. This will require a 200 Amp alternator and very heavy wiring. Whoa, the size of all this stuff is starting to become a problem.
As any electrical technician will tell you, to resolve the size issues with the cable and alternator, one simply needs to increase the voltage of the system. More Volts means less amps are needed. The number being thrown around currently is 48 Volts and several car companies have already jumped into action.
The Bentley Bentayga, for example, has a 48 Volt system, which it needs to drive an electrically-driven sway bar system. And Audi is using a 48 Volt system to power the industry’s first electric supercharger.
As more and more accessories and engine components become electrically powered, we should see most of car manufacturers jumping up to 48 Volts systems. Several have already announced their intentions to do so.