48 Volts DC is the new 12 Volts DC

Lloyd Alter July 22, 2019

48 volts for trailers photo
© Knaus Tabbert GmbH

Could it also be the new 120 Volts AC?

Being trained as an architect, I am kind of a generalist, having to know a bit about a whole lot of subjects. But whenever I talk about Direct Current vs Alternating current I come away singed and shocked by the comments, like my last one, where even fans noted, “This is about the most wrong article I’ve seen you write, Lloyd.”

But to this day, I do not understand why we have a system where every single light bulb now has to have a little transformer and rectifier to feed it DC, and almost everything we plug into the wall now has a transformer brick on it. Our domestic world now pretty much runs on DC.I do understand that P=VA and that the higher the current (the A or Amperage), the bigger the wire has to be. So 1000 watts at 12 volts needs wire the same size as 4000 watts at 48 volts. That’s why I was intrigued by the press release from Bosch, announcing a new “48-Volt electrical system specially for recreational vehicles in order to decisively and sustainably improve the self-sufficiency of caravans” (Trailers in Europe) for Knaus Tabbert, a big German manufacturer that churned out 23,643 caravans and motorhomes in 2018.

Caravan owners often dream of camping in secluded areas but unfortunately this desire for independence is often cut short by a lack of energy supply. The development of an innovative 48 Volt system, however, creates the basis for longer self-sufficient caravanning without compromising on essential comforts. In the future, campers will be able to enjoy the solitude of remote places for considerably longer than before without an external power source but equipped with powerful 48-Volt on-board voltage.

This is probably because they can pack solar panels on the roof and run more stuff with them with thinner wires. Vicor, a company making 48V products, notes that there is nothing new about 48V; it was developed by the telephone company to “increase efficiency by reducing voltage drop over long cables (as a percentage of the operational voltage), allowing the use of smaller gauge wire and simplifying battery backup while still operating at a voltage level considered to be safe.” It was more expensive historically because of the size and weight of the converters required for the higher voltage, but not any more in our solid-state world. Vicordescribes how it has become more common:

Today, it is widely documented that 48V is used in applications including data centers, automobiles, LED lighting, industrial equipment, and even power tools. It is impossible to go through a typical day and not see and use several 48V applications; 48V is the new 12V.

It seems that everything is going DC after all, even if it is 48V instead of 12V. Perhaps I was wrong all these years, and in fact 48V should be the new 120AC.