Automotive Industry migrates to 48V electrical system

I am planning to keep my present car as long as is practical, and I suspect it may be my final HF mobile installation. I have been doing HF mobile for 27 years as a long-distance commuter, through five cars. The cars have progressively gotten better in most ways but also noisier. The present one is still OK though there are still some birdies up and down the bands; but it took a lot of bonding and toroids to make it so.

Perhaps 5G will allow mobile HF ops via a pad with internet connection to an HF base station and a mobile-friendly graphic interface.

I have watched the noise floor in this suburban neighborhood rise from mostly negligible to S6 or sometimes much higher at times. With DSP and such, things are still manageable, but the trend is unmistakable. When I drive through other neighborhoods with my mobile rig the noise is sometimes insurmountable.

 

While there is technical merit to moving to a higher voltage, 48 volts is not likely, 24 volts maybe. The conversion cost expense, SEA, equipment mfg, and battery cost just could not be justified to the market with insignificant gains. 24 volts would stand a much better chance.

The main merits of going to higher voltage is weight, safety, and power density. Weight and safety are deadly serious in aircraft and marine industries. thus cost is warranted. In automotive weight is not as big of an issue, and the safety advantage is not near as critical coupled with relaxed standards on SAE wire sizes. Automotive is deeply ingrained in 12 volt world, and not going anywhere soon. If there is a change would only be 24 volts as there is already a market there for truckers, a blesing for RVer's with solar. I think some of the deisel Dodge Rams PU already use some 24 volt systems.

So only big advantage is a few pounds of weight savings in the wiring harnesses. Other than that, not much to be gained. You get just about much weight savings by switching to 24 volts with improved safety of 12 volt systems. Anything above that becomes diminishing returns.

The higher voltage fight should be made on our homes. 120 to 240 volt would greatly benefit all parties. Being first to electrify, the USA really screwed up using 240/120 single phase. We could save a lot of energy, making things less expensive, and more efficient. Not only more efficient but clean up electrical noise in a heartbeat switching to 240. Not only save consumers a lot of money, but help the environment wasting less energy. Even utilities would benefit with less wasted power, and a lot less ectrical noise to deal with.

 

Even for medium power. As an example, Ameritron ALS-500M needs 80A at 14V. 80A itself is not a joke. 80A is in recommended range for most 3/32” welding rods. 80A at just 13.6V means huge relative voltage drop so we must use short and very thick wire to deliver the power to an amp. Imaginary ALS-500M/48V will take some 20~25A which is incomparably easier in all senses.

Exactly.

It looks like you’ve got one or few already: HID xenon or LED headlights have their switching DC-DC converters. Even a phone charger is a simply DC-DC step-down.

I vote for 48V. 48V has only one disadvantage: huge, endless legacy which means DC-DCs and their RFI.

 

So, long story short -- MOAR POWR for HF mobile amps -- but more RFI as well. Bummer.

 

Hummm... How about Plutonium and all things radio active? Early days of the Atomic Age saw quite a few people getting sick from exposure. Scientists, Engineers, and Physicists all dove headlong into that technology without knowing the implications. How many above ground 'atmospheric' tests were carried out before they realized the fall out was dangerous? People used to drink water from containers lined with Radium. How headlong into stupid was that? Of course they didn't know the implications.... So I guess that made it ok. Does this qualify for a spot on the list?

Dan KI4AX

 

I wonder if the inventers of all the RFI generating junk out there considered the implications of the RFI their junk would emit? I would be willing to bet that they DID consider the implications for a second or two. Then they went ahead with the invention anyway.

When ever there is a lot of money to be made it's damn the RFI.... full steam ahead.

It's all about the money honey.....

Behind big money justice ALLWAYS FAILS.

Dan KI4AX

 

The phone call..

Management: Hey, we completed our first production run, but now they say it won't pass FCC."

RF Engineer: "It's midnight, can't this wait?

Management: "I'm serious, the CEO is gonna kill me. The Gizmo 3000 product team doesn't know what to do next."

RF Engineer: "Oh, it's those guys again. What's up with them? I helped them on that G3000 six months ago."

Management: "They really appreciated your input at that design meeting. But, Jack took your inductors off the board. He doesn't like inductors."

RF Engineer: "Uh huh. Riiiight. Take 2 ferrites and call me in the morning."

Click.

 

How about choice D, Under-financed?

Large parts of our area are waiting for 2G coverage along the highways. A lot of the reason is because money for building towers is not unlimited, and available spending goes first to where the paying customers are concentrated. Pick off the low-hanging fruit first, as they say.

Yes, there are five or six built-up areas in my travels where you can get 4G for a couple of miles, but these are separated by 25-mile stretches of zero, zilch, zip, nada cellular communications. I do know of two residences in the middle of dead zones along two State highways where I have permission to pull over near the house and access their 2G internet-connected Verizon femtocells.

All of this lack of rural coverage means that if it is really true they are making 'smart' cars that won't run if they can't access a cloud server, those cars won't work here. I find it a little bit hard to believe there would be no autonomous back-up system, but I've been surprised by technology before.

 

All three

 

Well a lawyers dream, 48v can kill somebody with a dicky ticker. Marine tech and I were just talking about this two days ago. Everything should be 24v but not 48v. Litigation nightmare. I wonder which manufacturer of vehicles will be the first to go broke? As mentioned previously, sustained arc, sufficient skin effect to affect adjacent wiring in parallel. My XYL's car had a high resistant joint in a connector, it melted at 12v, can you imagine the same connector at 48v!

Anyway, the theory guys will work it out without any practical real world experience as so often happens these days.

 

You're right, Chip. 5G was my industry and as of my retirement a few months ago, I can tell you AT&T was working on the issue.

And the point he made also assumes losing a connection will make your car die. That won't happen. No manufacturer wants that bad publicity. It may use 5G for diagnostics or in vehicle internet service, perhaps vehicle location or navigation info all of which can work on 3G if it has to.

Finally, I agree that cars will probably not be 48V for safety reasons.

 

What does Tesla do for power steering?

Power windows?

To run the blower for AC and heat? Defrost?

 

re: "When I worked for Motorola we had special Micor and Spectra transceivers just for locomotives because they use 72 volts. "

And before that - the MOTRAC series had a design for railroad use; they had a DC-DC converter already on board those mostly transistorized "sleds" ...

 

I wonder ... if the 2 Volt (given the electro-potential of lead acid battery) system existed before that? (Or maybe 4 Volt?)

 

Tesla owner here - There is a small 12V lead acid battery that powers the windows and some other stuff like the onboard computer and lights. It's charged when needed by a buck/boost converter from the main propulsion battery underneath the car. The AC compressor, resistive cabin heater, and power steering are all "high-voltage" and are powered by the main battery. The Model 3 does not have a dedicated battery heater, but the Models S and X do. There has been talk of abandoning the 12V battery entirely, but for now they are still being used.

Are you talking about Tesla when you say "smart cars"? It's true that they need an internet connection to ping Tesla's servers for things like location tracking and also general software updates. The car doesn't need 5G to drive or do anything, however. Home wifi or LTE is fine for updates. Operation by smartphone is only possible when there is no driver present, such as when backing the car into the garage using "summon". There is no "basically you're driving along and suddenly lose your car's 5G internet connection and your car suddenly stops dead" with a Tesla. If it loses its internet connection, you'll be unable to listen to internet radio, but the car will keep moving just fine. There is either a keycard or key fob that allows the driver to use the car sans any network at all.