Media post: Maybe 12 volts isn’t enough anymore

1954 Cadillac Sixty Two

In the early part of the 1900s, cars all had 6 volt systems. Back then a 6 volt system was perfectly capable of powering the starter, lights and other accessories that the cars and trucks of the time had in them. Things changed in the 1950s, though.

In the 1950s, Detroit started the power accessory revolution. Things like power windows, power seats, power antennas, radios, air conditioning and other accessories all started to appear. Unfortunately, this caused a problem for engineers who were taxed with the task of designing an electrical system that could power all these accessories.

The solution came from General Motors who in 1954 offered a 12 volt system in their Cadillac Series 62 models. The rest of the American car industry quickly followed suit and soon every passenger car and truck made had a 12 volt electrical system. The results were significant. Ken Garff Used in West Valley City, UT tells us that vehicles with 12 volt systems started faster and multiple accessories, like the radio and AC could be used at the same time.

As the number of automotive gadgets climbs, however, the industry is wondering what to do. Today’s cars offer a buffet of new electronic technology and car engines themselves, which traditionally used little electrical power, now have lots of electrically powered components.

So, wouldn’t a simple solution be to just beef up the existing 12 Volt system? Let’s do a little math and see how it all adds up. Take all the power consumed by all the electrical accessories in a new car-the power windows, the defroster, the heated seats-and the total will probably be between some 1.5 and 2.0 kilowatts. To supply 2.0 kilowatts of power, a standard alternator must be capable of churning out more than 140 amps. Not a problem, especially with the new water-cooled designs. But size up a 14-volt alternator to feed the 3.0 kilowatts of power expected in cars built later this decade, and you’re looking at 200 amps. This is an entirely different matter because wiring that is capable of carrying 200 amps is extremely thick and expensive.

So to drop the cable and alternator size issues, one simply needs to increase the voltage of the system. The number being thrown around currently is 36 volts. 36 volt systems would be just about right to power the complex demands of today’s automobiles and provide plenty of reserve for the future.

That being said, the car companies are hesitant to switch to 36 volts. There are some downsides. Electrical components will corrode more quickly and potential arcing are two major reliability issues. Plus, many devices in an automobile just prefer fewer volts. Light-bulb filaments, for example, grow too long and flimsy if designed to handle more than 12 volts and smaller, low-amp electric motors must be wound with special extra-thin wire that increases cost.

So, today we have a wait-and-see thing going on. Several manufacturers are experimenting with 36 volt systems but none have decided to go into production yet.