Future Vehicle Voltages, 12 or 24?

Many North American automobiles up until the mid ‘50’s were equipped with a 6 volt electrical system.   This changed to a 12 volt system over a couple of years on pretty well all makes of vehicles.   This still stands today, with even many large class A motor coaches using 12 volt direct current as their main operating electrical power.  This is, however, in contrast to many bus conversion type rigs which have adapted to a 24 volt D.C. system. 

So, which is better, 12 or 24 volt direct current?  Why did larger vehicles, including highway buses, opt for this higher operating voltage?   To understand that, we should look to what the driving forces were behind the automotive industry back when 6 volt systems were replaced with 12.  The higher voltage offered better reliability and ability to operate more accessories in a more efficient manner.  Cold weather starting was greatly improved by using higher voltage starter motors.  Additionally, wire gauge could be substantially reduced in size, so that the harness would be only half the size and weight that was required for a 6 volt system.  For battery cables and ground cables and straps, this would be a substantial weight and cost reduction.  For example, a six volt operating system uses battery cables about the diameter of your thumb, while a 12 volt system only has cables equal to the size of your pinky.  This is due to the amperage being only half that required by the lower voltage.   Inverters also increase in efficiency dramatically with higher input voltages.  

The normal push-back for this type of system revolves around availability of electronic accessories in that voltage range.  The fact is, many electronic devices currently accept 12 to 30 plus volts dc, as is.  Additionally there is no problem running a low load 12 volt feed off the battery bank running parallel on the 12 volt power side. 

So, we are paying somewhere between $100,000 and $800,000 for an option filled motor coach that employs a 12 volt electrical system.   Many other large or specialized vehicles are equipped with 24 volt systems.  Not only conversion buses are using the higher voltage, but so are aircraft.  Many airplanes also use higher d.c. voltages ranging from 24 to 48 volts.  For aircraft, weight is certainly the main issue supporting the higher d.c. voltages, however, reliability is probably a close second.    

 

So, what about it, let’s hear from you.  Is higher d.c. voltage the way to go for today’s motor homes?  Have we just been given a less efficient voltage because the manufacturer has a better selection of 12 volt accessories?  It has to make you wonder.

What do you, think? 

 

Wondering About A Higher Power   –    Lug_Nut    –     Peter Mercer