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.
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
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. :)
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.
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?
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.
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.
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