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Can 48V Be the Auto Industry's Next Big Thing?

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naperlou
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Incremental is good
naperlou   7/30/2013 9:56:27 AM
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Chuck, it seems that this would be an incremental increase (15%) that would be a lot less costly than a full hybrid or EV.  This is a good thing.  Couple that with increases in efficiency in the ICE and increased aerodynamics and you can easily reach the CAFE goals for a very reasonable price. 

I am also impressed that this system would run the A/C and other heavy loads on the engine.  The disturbing trend in autos today is increased power in the same displacement.  If instead of increasing power by 20%, the displacement was decreased by 20%, then fuel efficiency would go up almost for free (no new, exotic technology).  For example, the Chrysler 3.5L V6 that was first used in their LH cars produces 250HP.  As a comparison, my dad's 1970 Olds Delta 88 with a 5.7L (350 CuIn) V8 produced 250HP.  The newest 3.5L V6s produce about 300HP.  Now, if we just use a 3L at 250HP, then gas mileage would go up accordingly.  Believe me, 250HP is enough for a 3,600lb automobile to go fast.  If you take the load of the A/C and other items off the ICE, then you can lower the HP even more for the same performance. 

Why hasn't this happened?  Maybe the standards should be tighter, sooner.

ragtoplvr
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Re: Incremental is good
ragtoplvr   7/31/2013 9:00:57 AM
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As I recall, there were 2 issues on the 42V

1.  Higher voltage FETS were too expensive

2  42V incadescent light bulb life in automotive environment was too short.

Both these are no longer issues.

 

Rod

Jack.L
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Re: Incremental is good
Jack.L   7/31/2013 10:13:20 AM
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Because fuel price shock has not completely set in for consumers. They don't see yet that they may be paying $5000 - $10000 more over the life of the vehicle for additional fuel versus what they could be paying.  I am still surprised to see people use pickup trucks as mainly commuting vehicles. Over a 120,000 mile life of the vehicle they could be easily paying $10,000 more in fuel versus a mid-sized sedan.

I do get the whole tow vehicle thing. The market has not really addressed the efficient tow vehicle yet. Part of the problem, in N.A. at least is outrageous power requirements. There is an expectation of car like performance even while towing it seems.

Watashi
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Re: Incremental is good
Watashi   7/31/2013 12:25:06 PM
The bar has been set.

You can't unring a bell and there is no gold medal for second place. Technologies will compete or die.

...or the unethical can lobby political hacks to distort the market for them; so their hobby shop widgets can have a chance to lower everybody's standards.

 Yes – I need to be able to pull a loaded 3 horse slant uphill at 70mph!

 

Reliabilityguru
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Miraculous EU Marketplace
Reliabilityguru   7/30/2013 10:53:20 AM
Extraordinary "in Europe, approximately 50 percent of the cars produced this year will be start-stop vehicles". That's about as universal as it gets in a free market. How are the EU consumers being coerced?

tekochip
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Re: Miraculous EU Marketplace
tekochip   7/30/2013 1:55:13 PM
They pay more for fuel.

Charles Murray
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Re: Miraculous EU Marketplace
Charles Murray   7/30/2013 6:54:58 PM
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You nailed it, tekochip. That's the driver.

Reliabilityguru
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Re: Miraculous EU Marketplace
Reliabilityguru   7/31/2013 9:52:48 AM
In reliability engineering we have a term: root cause.  As in, Europeans are coerced into stop start by higher taxes. Europeans pay more for fuel than us in North America due to taxes and import duties. And this was not brought about by noble environmental concerns. It is well known, they paid much more than us before the environment was a convenient excuse. Before global cooling transformed to global warming transformed to climate change, remember the European 60's muscle cars? Me neither.  

We need cheap energy and now our government is in the way. Nuclear power and now coal is being regulated out of existence. There is a reason the Saudi's are scared to death of oil shale and fracking. We could easily have $2 a gallon gasoline in North America if BIG OIL was allowed to exploit our resources. This is not about the environment either. The environmental movement is just a means to an ends. Every new energy technology that shows promise gets beaten with that stick. Cheap energy would bring us out of this economic quagmire faster than a bullet train and reduce the real unemployment rate below 12%. It could save our economy in spite of the socialist utopians.  

etmax
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Re: Miraculous EU Marketplace
etmax   8/8/2013 10:09:26 PM
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I don't think you can blame unemployment on current fuel prices, the US has very low fuel prices (based on global levels) yet has much higher unemployment. If anything that would indicate that high fuel prices lower unemployment. Of course that isn't the case either. What it is are 2 things, first there are not enough people earning enough money to be able to spend it in the wider economy therefore the economy is sluggish. If some of the money that is in the hands of the super rich and is spent on enormous mansions and $1000 handbags were distributed to the 30% of the population that can only afford to eat and shelter things would look better

etmax
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Re: Miraculous EU Marketplace
etmax   8/8/2013 10:35:14 PM
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Hi Charles, I often wondered why a technology (42V) that even Delco was touting as being the next big thing died, but at the end of the day it did add a lot of unnecessary cost at the time. Now 48V and a lithium battery it seems an even greater cost is being introduced, and given the deadly combination of a lithium battery and lots of falmmable plastics and fuel I thing the battery will have to be armour plated and placed within the confines of the passenger safety cell to avoid a catastrophe in an accident. Another show stopper I see is the LV directive that cuts out at 42V (possibly one of the reasons why 42V was chosen) so it will be interesting to see how it pans out. I don't think I'm going to hold my breath, as to me it looks like another attempt to sell a new idea for not too much added value. I've don't measurements on my car and the A/C uses very little, something around 1-2%

Charles Murray
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Re: Miraculous EU Marketplace
Charles Murray   8/13/2013 6:37:30 PM
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As you point out, there are a lot of very good reasons to question the viability of this idea, etmax. The one big thing it has going for it, though, is the inevitability of start-stop technology. Higher voltages are better for the operation of the starter-generator. And 48V lithium-ion is better at capturing that regen energy. As you say, it will be interesting to see (and if) this pans out.

etmax
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Re: Miraculous EU Marketplace
etmax   8/14/2013 10:22:42 AM
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:-) I agree, and it's not always the best ideas that make it, only the ones that capture the imagination of the buyer/are better marketed (to a point). As a funny life experience with start/stop technology, in 1972 I had the clutch cable break on my 1965 beetle while waiting to drive on a ferry. I turned off the ignition, put it in reverse and turned the key then did the same in forward/reverse/forward again doing a 3 point turn and then proceeded to drive to a workshop by the same means. Once in first I could change gears by revving just the right amount AND THAT WAS A 6 VOLT SYSTEM :-)

but i do agree, even though every actual start/stop car I've driven this year has been a 12V system, charge recovery has to be better with higher voltages.

Someone will have to figure out at what fuel price point the expense of 48V etc. is justified.

If I may ramble on, I have often wondered about start/stop from an emissions and consumption standpoint, because a partially warmed engine uses about 20-30% more fuel, has significantly higher engine wear, and emissions are more difficult to control during warm up as well. This is partially because of catalytic converter temperatures. I know they can electrically heat them, but that's more fuel too, so I would be interested in knowing how much benefit there is if you're not stuck at a level train crossing for 10 minutes. I'm not saying stop/start isn't a good idea, only asking is it? and how good?

Charles Murray
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Re: Miraculous EU Marketplace
Charles Murray   7/30/2013 6:54:20 PM
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I detect a trace of irony in your question, but as I think you are pointing out here, they're not being coerced. There was no mandate. Start-stop came into being as a way of lowering emissions, and then European consumers just wanted it.

J. Williams
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Re: Miraculous EU Marketplace
J. Williams   7/31/2013 11:54:21 AM
When you pay $7-8 per gallon (primarily because of punitive taxes) you ARE being coerced.  Plain and simple.

a.saji
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Re: Miraculous EU Marketplace
a.saji   7/31/2013 10:49:56 PM
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@William: I think the price range is high isn't it ? Per gallon that much ?  

Reliabilityguru
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Re: Miraculous EU Marketplace
Reliabilityguru   8/9/2013 9:30:22 AM
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EU prices range from $7/gal in Spain to $9/gal Norway. Almost all are between 8 and 9. The difference in price between US and Europe is taxes.

More of what they pay goes to big government than big oil. One would think big government was not just overhead.

apresher
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42 Volts
apresher   7/30/2013 9:04:45 PM
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Chuck,  I did an article on 42 volt systems 7-8 years ago, and the concerns were $ and safety. It looked at one point like 42v systems would be gaining a foothold, but within a year or two the tide had turned. Any idea if these factors (I'm sure $ is important) are still front and center? Thanks.

Jim_E
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Re: 48 Volts
Jim_E   7/31/2013 9:06:23 AM
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I recall the earlier articles saying that 42v was the upper limit of safe voltage in the vehicle for the end user.  Now, 48v is okay?

I'm more concerned about a lithium ion battery in my engine compartment.  It's one of the worst environments for a battery with the heat from the engine, and being exposed to the elements.  After reading about the issues with lithium ion batteries catching fire, one place that I do not want a big one, is in my car, where I have plenty of gasoline and other combustible matter!

I hope that traditional compressor based air conditioning will someday be replaced by new technology.  Wasn't there some "sonic" air conditioner invented a while ago?  A peltier junction based system (or similar technology) with no refrigerant and associated piping would be a wonderful thing.

 

Jack.L
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Re: 48 Volts
Jack.L   7/31/2013 10:02:40 AM
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Jim_E,

 

There are numerous battery compositions that fall under the heading of Lithium-Ion. These range from the dangerous if treated poorly but very common LiCo02 batteries that are in our laptops, to quite benign LiFeP04 with a range of options in between. LiFeP04 has much better high temp characteristics versus lead-acid. I would not have any concerns with this type of battery in my car. We also need to be realistic. We are already sitting on a large capacity of highly flammable liquid and we do that without thinking.

Jack.L
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Re: 48 Volts
Jack.L   7/31/2013 10:05:35 AM
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The lowly compressor is significantly more efficient than even the best peltier cooling devices.

Jim_E
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Re: Compressor
Jim_E   7/31/2013 10:13:41 AM
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I believe you, but it's a real mess having the belt driven compressor, condensor, piping, evaporator, etc. under the hood of the car!  I've love for there to be some other technology which would offer equivalent cooling ability, but be powered by electricity without the need for all of that junk.  I just want a box that attaches to the firewall with some wires that go into it.  :)

 

etmax
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Re: 48 Volts
etmax   8/8/2013 10:14:36 PM
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You have hit the nail on the head, 42V is the upper limit of the LV directive which covers most of the globe. An auto electrician wouldn't be able to work on a 48V system in most countries

 

MVRS
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Re: 48 Volts
MVRS   8/8/2013 10:33:27 PM
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Put the battery in the trunk (like some cars already do).  The climate is more temperate than the engine bay.

etmax
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Re: 48 Volts
etmax   8/14/2013 10:26:15 AM
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But lithium batteries are safe, they are certified for use on aircraft! Oh wait, I think several planes were sent to the shop due to in flight fires :-)

ungarata
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Efficiency numbers
ungarata   7/31/2013 9:17:51 AM
Any time I see projected numbers like the efficiency numbers mentioned here, I immediately take the number down to 1/3 the projected number.  I've found that to be far more accurate when it comes to real-world results.  At times I've seen it be up to half the initial projected numbers, but that's about it.

If the people who are advocating new technologies would put out real-world expected gains instead of "up to" pie-in-the-sky numbers, their credibility for future projects would be helped.  "Up to" numbers assume that everything is ideal, works perfectly, etc., and they usually just are not valid.

For this project, if they're stating that fuel economy will go up by "possibly as much as 15 percent", then I would place a very large bet that the actual increase will be about five percent once the system is rolled out and all the real-world constraints come into play.

I would be far less skeptical of improvement claims if the projected improvement numbers weren't usually overinflated to get people to buy into the concept.

Jack.L
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Re: Efficiency numbers
Jack.L   7/31/2013 9:54:57 AM
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I do not think the 15% efficiency claim is 3x overstated so much as the operational conditions are not stated.

On the highway, a system such as this will provide only limited benefits such as not having the AC compressor directly connected during high revving.

On the other hand, in bumper/bumper and city driving regenerative breaking, start/stop, etc. like in hybrids can significantly increase fuel economy. What this really is is a mild hybrid.

 

wskehr
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it's about time for Regerative braking
wskehr   7/31/2013 9:22:48 AM
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If 48V is what is needed to allow putting regerative braking in autos, then this could catch on quickly with drivers that spend most of their time in the city. 

The dual voltage idea is clever.  All the 12V lighting and other functions that currently exists don't need to be redisigned and people can appreciate that they are still interfacing with only 12V components.

Ken E.
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Why not just be rid of the 12v battery altogether?
Ken E.   7/31/2013 9:22:55 AM
If the Li battery has higher power density, what's the point of the heavy lead acid battery, and associated heavy wiring and components?  And couldn't even that lead acid battery be available in a 48v version too? 

Is the concern an ability to 'jump start' the cars?  I ran both my Prius batteries down once (a shameful story I won't go into) and it wouldn't jump start anyhow- the computer memory was gone.

Jack.L
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Re: Why not just be rid of the 12v battery altogether?
Jack.L   7/31/2013 9:51:57 AM
The issue with 48V lead-acid is weight/energy density. The added weight of lead acid will cut into the efficiency gains of the system.

Ken E.
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Re: Why not just be rid of the 12v battery altogether?
Ken E.   7/31/2013 10:07:04 AM
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Jack,I don't understand why the weight/energy density of a lead acid would change significantly for 12v vs 48v.  Seems there whould be more cells, but smaller, (1/4 the amps required) for roughly the same energy density. 

Jack.L
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Re: Why not just be rid of the 12v battery altogether?
Jack.L   7/31/2013 10:49:07 AM
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It is not the issue of the weight /energy density of a 48V lead acid versus a 12V lead acid, it is the weight/energy (and power) density versus the equivalent lithium battery.

There is work on mild-hybrid using lead-acid-carbon batteries that have far longer life, good power density, but worse energy density versus standard lead-acid.

Dom
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Re: Why not just be rid of the 12v battery altogether?
Dom   7/31/2013 10:48:29 AM
Jack getting rid of the 12V battey in this case no interest at all : imagine putting DC/DC converter on every single consumer that works under 12V! better centralize with one DC/DC converter + 12V battery which in this case become very small since no need to compromize like today between energy(consumer feeding) and power (starter motor powering) but only energy in this case battery are half the size and the cost not a pb.
the real interest of this architecture is the combination with downsizing like 2 cylinder ICE (1000cc) and 6kW electric machine that's the good fit and very good FE

Jack.L
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Re: Why not just be rid of the 12v battery altogether?
Jack.L   7/31/2013 10:52:10 AM
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I was not suggesting removal of the 12v battery. I fully see the advantage of this architecture. To your point, legacy 12V support when it does not need to start the vehicle is quite easy and less expensive.

 

etmax
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Re: Why not just be rid of the 12v battery altogether?
etmax   8/14/2013 10:33:26 AM
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Not having to start the car any more the 12V battery would only need to have a 1/4 of the capacity.

Dom
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48V on board cars
Dom   7/31/2013 9:40:12 AM
I have been working on these dual voltage network for years some roadblocks have gone away today

- downsizing of motors is a reality today a 1.6l engine delivers 120HP (in Europe !!)
- if we want to go further in downsizing the lack of power at low throttle will be such that electric compensation becomes necessary w/o going to full hybrid that is the most  economical way to improve FE
- the 48V will be devoted to high power electric consumers only, before dual network was eveywhere raising FMEA pb that were non solvable
- Li-ion battery is for sure now a reality and such a battery can easily fit in the rear trunk w/o any risk at least not bigger that the big pack of hybrid that's behing the backrow seats !!
- our conclusion was that FE could be boosted by 25% combined with downsizing at this time the market was not ready to pay for this technology

o tempora o mores !

ltron
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Re: 48V on board cars
ltron   7/31/2013 10:22:45 AM
I'm not sure why we don't dump the 12V Lead Acid battery entirely. They could easily use 48V for any high power loads and provide a 12V step down converter for legacy 12V low power loads.

It would be an easy 50lbs savings.

 

bob from maine
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Re: 48V on board cars
bob from maine   7/31/2013 11:02:19 AM
Let's see. We're going to add a 48V battery and charging assembly, a regenerative electric assembly between the wheels and engine to help recharge the 48V battery pack; retain the 12V battery and charging system for starting and other legacy loads AND we're going to increase fuel efficiency by "up to" 15%. Right! The idea of increasing system voltage to reduce current is needed. Current luxury cars draw as much as 80A continuously while running all the entertainment and climate systems and we're adding more loads all the time. Recent brushless DC motors can do an admirable job running air conditioning by varying the speed of the compressor to meet the load, but it would run so much more efficiently if it could run on 48V instead of 12. Changing to 48V would impose a significant penalty on automotive manufacturers to develop the technology and manufacturing capability to supply both 12 and 48. It is not a trivial change and we need to have ONE voltage that all manufacturers will use. I really don't see auto manufacturers giving up their competitive advantage by adopting the same system as some other maker.

Jack.L
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Re: 48V on board cars
Jack.L   7/31/2013 11:24:13 AM
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Competitors in the automotive space routinely engage in joint-ventures as a way of mitigating risk and to be more competitive against other stronger competitors. There is already a ton of standardization in automotive. Why would one expect there to be any less?

Only electric driven AC systems from my knowledge draw anything near 80A continous. Entertainment systems may have high peaks but average draw i quite low, lighting loads are lower now, etc.

billvon
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Re: 48V on board cars
billvon   7/31/2013 12:53:12 PM
Yes, the plan is to to add a 48V battery and charging assembly and a regenerative assist motor - and lose the current alternator/large 12V battery.  Overall that's about a wash weight wise (bigger motor/generator but less copper.)

 

The old Honda Civic Hybrid did something very similar to this and used a 'weak hybrid' approach (which is what this basically is.)  Even though the car was heavier fuel economy went up significantly.

 

The biggest competition to this is not going to be better 12V systems but current HV (200-500V) hybrid systems.    They exist now and solve many of the problems that the 48V system is trying to solve.

Watashi
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Am I missing something here?
Watashi   7/31/2013 9:48:46 AM
Start-Stop and Regenerative Braking are Hybrid terms.  This assumes a hybrid or 'hybrid lite' drivetrain.  But 48V is a very poor choice for providing drivetrain power.  If you are going to have a hybrid, just use the 300+ Volts.  If you are not going to have a hybrid, don't add a bunch of parts (weight/cost) just to support a secondary voltage architecture.

I was very much onboard with the 42V or 48V back 10 or so years ago.  The advantages in terms of weight (smaller conductors) and beltless accessories are substantial.  The 'three batteries' was a short term solution, but an adequate, single battery could have been available by the time a production car rolled out. 

The largest obstacle I recall was the prevalence of 12V parts.  The fact that a car manufacturer along with all the electronics providers would have to start from scratch is a major risk for a company to undertake.  Staying with 12V is much easier than dealing with things like unknown component reliability and a non-existent supply chain.

Jack.L
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Re: Am I missing something here?
Jack.L   7/31/2013 9:57:29 AM
Watashi, the issue with 300V, is that requires a 300V battery solution and everything to be 300V that is connected (i.e. AC compressor, etc.). 300V charging and control, safety systems, etc. are all more expensive than 48V. The goal here is mass adoption.

Watashi
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Re: Am I missing something here?
Watashi   7/31/2013 11:23:20 AM
I assume that it is hybrids we are talking about and high voltage is still needed for the powertrain.  Low voltages like 48V can be supplied by the high voltage system.  I would think a DC/DC converter is more economical and efficient than adding a whole other system to the vehicle.

I don't see how this makes sense if we are talking no high voltage.  State of the art hybrid is only a marginal improvement over 'fuel efficient' ICE only designs as it is.  Using less electrical power will only drop the contribution it makes to the vehicle. 

Like I said – I think I'm missing something implied in the article.  

Jack.L
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Re: Am I missing something here?
Jack.L   7/31/2013 11:28:20 AM
Watashi, your comment about hybrids being only marginally better than state of the art ICE is true for highway cycle mileage, but in city driving, and stop and go traffic, hybrids are significantly more efficient.

Watashi
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Re: Am I missing something here?
Watashi   7/31/2013 12:09:07 PM
True – but then we are discussing a change that would only affect a portion of the market.  With the 'mild hybrid' that segment would lose some of the hybrid advantage they already enjoy.  Highway is ICE territory and hybrids struggle to match them there.  Overall, we are talking about a change that would further divide a market niche and would be hard pressed to match MPG with much lower priced non-hybrids.

If this is just a way to phase in 48V to the whole market and spur development of 48V compatible automotive electronics than maybe it makes some kind of sense (or what passes for sense these days).  Like I said, I see the advantage to going 48V across the board as standard in automotive applications. 

I definitely won't be one of the early adopters here.  I'll have to let the marketing susceptible consumer base spend their money to develop the parts I want.

Jack.L
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Re: Am I missing something here?
Jack.L   7/31/2013 1:49:21 PM
This is not about pushing 48V electronics which would only happen if the costs demanded it.

 

What this is is a method to bring mild-hybrd to the market at far less cost than existing proprietary lower volume but arguably better hybrid systems.

48V can lend some advantages to ICE in terms of electrically actuated valves which work better when you can drive them harder.

The 48V section will be contained to keep wiring costs lower so I am not too worried about CAN not being able to take a hit as the likelihook of that is pretty low. Sure there will be some missteps but that is what progress takes .. failure.

 

The goal is to have this on the majority of vehicles especially those that spend a lot of time in the city, which many cars do in much of the world.

 

Gas prices are not likely to go down as no matter how cheap we can pull oil out of the ground in North America, prices will still be set by the world market and demand does not seem to be going down.

 

 

cgosnell
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Nothing comes for free...
cgosnell   7/31/2013 10:07:18 AM
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In several of the posts, I heard claims that the 48V accessories will take load off the engine and improve efficiency.  

While I agree that some increased efficiency will be had by using an electric power steering assist vs. hydraulic due to the idling losses in the hydraulic system, I don't see a big improvement for the A/C system as A/C compressors already have clutches to remove their load from the engine when not used and when under hard acceleration.

I agree that recovering regen braking energy and then using it for peak loads may be a good idea, but for extended driving periods the A/C system will use up any (all) of the regen stored energy requiring makeup by the Alternator.

Will the Alternators have dual 12V-48V outputs, or will they just run at 48V and be stepped down to 12V using the recharging electronics?  

Given the losses involved with electric driven A/C, wouldn't it be more efficient just to leave the A/C compressors as-is?

Just my $.02

Jack.L
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Re: Nothing comes for free...
Jack.L   7/31/2013 10:59:16 AM
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The clutch may disengage under hard acceleration, but it is still operating normally under a range of say 800 - 2500rpm. Electric driven it will work at one ideal rpm. Electric motors and generators are fairly efficient so while there are losses, they are less than ideal operation of the compressor. We do need to take into account battery turnaround losses as well, but again, they are low. The AC can be electrical driven at variable speed to adapt to the cooling requirements further reducing energy draw.

 

jcdammeyer
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48V systems and CAN bus.
jcdammeyer   7/31/2013 12:08:35 PM
Most of the CAN transceievers are not tolerant against 48V (or the charging voltage for 48V batteries) on the CAN bus.  For a 48V system to take hold the transceivers have to be improved before I'd use a 48V supply again.  I watched 50 nodes go up in smoke once when a bad cable shorted 48V onto CAN_H.  The cable tested fine before installation.

OcelotZ3
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Coercion...
OcelotZ3   7/31/2013 1:46:37 PM
Folks say that the Europeans are being "coerced" by higher gas prices.  If our prices reflected all the government puts into the oil industry (military interventions, subsidizing advertising for the oil industry, etc.), our price/gal would be much higher than it is now.  Personally, I would support this.  (After removing government subsidies for the oil industry).

MIROX
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48 V - my vote is YES !!!
MIROX   7/31/2013 4:00:40 PM
We make NEV that uses 48V DC to power 3 phase 32 to 36 V AC motor, and regenerative braking is a big plus in comparison to 48 V DC Serial Motor.

But the BIG plus for mild hybrid or even ICE car is that you can run Air Conditioning, Water and Oil pumps from 48 V (actually as much as 56 V on fully charged battery pack) with lot less current, for which MOSFET are already available at low costs.

40A DC or AC motor for Air Conditioning is no issue to control with 48V, but up that AMP to 160 A for equivalent power at 12 to 14 V and it is problematic and very expensive.

Of course this is IN addition to normal 12 V DC Automotive system, but then STARTER, ALTERNATOR are eliminated and regenerative braking via power train as well as FREE START STOP is part of the deal.

4kWH battery pack is quite adequate and Sealed Pb-acid technology at 1/4 the price of Li-ion will do just fine with up to 7 years or service life per battery that will cost about $1,200 retail to replace.

The biggest POSITIVE from consumer research is that Air Conditioning can be run in recycle mode when vehicle is parked for up to about 45 minutes and keep the car cool inside even at 120 F in direct sunlight, something that is great for TAXI and LIMO services in places like Phoenix and Las Vegas.

 

 

Charles Murray
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Re: 48 V - my vote is YES !!!
Charles Murray   7/31/2013 6:16:32 PM
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Great points, Mirox, especially about air conditioning applications. Regarding the choice of li-ion over lead-acid: Again you are correct, lead-acid will give a big cost advantage. The reason some automakers are looking at li-ion for these applications is volume and weight. A 48V lithium-ion battery can replace three 12V lead-acid batteries, so automotive engineers get a packaging advantage, as well as a weight advantage. Weight becomes especially important with automakers facing 54.5-mpg CAFE standards in 2025. Every little advantage counts. But as you accurately point out, they will have to bite the bullet on cost if they do that. Great comments.

MIROX
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Re: 48 V - my vote is YES !!!
MIROX   8/1/2013 2:12:11 AM
@Charles Murray 

With about 10 years of experience with NEV (limited to 25 MPH by federal law, but allowed to go up to 35 MPH in few states) we have actual proof that when it comes to effective regenerative braking, weight actualy does not matter in EV or Hybrid as the energy gets recouped rather well from the "extra" weight.

in ICE ONLY vehicle it DEFINITELY matters, but not in EV !!!

Pd-acid sealed batteries (gell or AGM) can especially take huge current pulses over few seconds of braking with no problem or special battery management, not so for Li-ion there you need $$$ in BMS just to protect the batteries, or MUST add super caps to store the energy.

2kWh pack in Pb-acid is about 160 lbs, but 4kWh pack that is double the weight gives 260% better range, by "theoretical" calculations it should only be 180% due to extra weight on car that starts at 1520 lbs.

So the "extra" weight actually assists in energy regeneration, especially on down hill, the "lighter car" will generate lot less energy and will freewheel by gravity at lower terminal speed on the same downhill.

This is REAL LIFE experience, that actually surprised us.

Of course at some point you reach point of no "gain" but not sure where that is for car with conventional tires and same Cdx.

We only tested the same vehicle to 1850 lbs as adding more batteries was not possible due to space limitations, but more weight (even 4 passengers versus just one driver) actually DOES NOT reduce the range, and usually increases it !

Charles Murray
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Re: 48 V - my vote is YES !!!
Charles Murray   8/1/2013 7:23:50 PM
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That's great information. Thanks, Mirox!

apresher
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Safety a Concern
apresher   8/1/2013 9:52:38 PM
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Still wondering if safety is an issue to overcome.  My understanding is that voltages this high could be lethal if not handled correctly. Anyone know if that is true for these systems?

MIROX
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Platinum
Re: Safety a Concern
MIROX   8/1/2013 11:23:34 PM
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FMVSS #305 

This standard applies
to passenger cars, and to multipurpose
passenger vehicles, trucks and buses
with a GVWR of 4536 kg or less, that
use more than 48 nominal volts of electricity
as propulsion power and whose
speed attainable in 1.6 km on a paved
level surface is more than 40 km/h.

 

SO 48V "nominal" is not a safety issue as far as NHTSA/DOT is concerned.

apresher
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48V Safety
apresher   8/2/2013 8:38:15 AM
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Mirox,  Thanks for the additional info on safety of these systems.

AnandY
User Rank
Gold
RE: 48 V my answer is a YES
AnandY   8/8/2013 3:26:15 AM
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 The lithium ion battery technique will enable for the recapture of battery energy as it has been put by Charles. The use 48 V in the locomotives will no doubt lead to a cheaper and efficient method of locomotion. The answer to 48 V is therefore definitely a yes.

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