Featured Bosch 48V battery

I guess that depends on what the 2025 CAFE regs are by then.

 

And whether the number is truly global. The main push for these systems is for reducing emissions. Something India and China are both concerned with in their car fleets.

 

There are 3 drivers for 48VDC start stop systems-

Standardized electronic power steering and brake boost versus hydraulic not only is more efficient but also may be necessary for advanced features like automatic braking and lane keep assist.

Start/stop heavy duty starter and/or alternator and/or motor/generator along with that electric power steering and brake boost and electronic water pumps, significantly decreases ghg on the european tests.

e-chargers (an electronic supercharging of a mechanical turbo charger, or an electronic/mechanical supercharger first introduced to the mass market by vw group) require the higher power of a 48V system, and provides better NVH and efficiency than a traditional turbo charger. Ford and Honda are looking closely at the technology and added costs. BMW thinks its twin scroll turbo chargers and variable lift valves are good enough.

The pick of 48V is mainly regulatory, over 60 V requires more tests and and orange cables and more safety equipment. They just as easily have picked 42 volts (the old proposal) or 60 volts. This could be a winner, and really go into all those predicted cars. Limh and Lithium polymer keep going down in price making this technology an inexpensive way to comply with regulations in europe.

Delphi and JCI both are promoting a 48V standard. They both are though talking about hybrid 48V for the high power applications and 12 V for accessories and entertainment. Audi is trying to get these to 48V so they can roll it out more cheaply to the vw group. I say getting rid of 12 V is a long shot on non plug-ins. Who knows maybe vw group and honda can get enough suppliers to get 48V complete systems.

 

I think the main driver of actual 48 volt adoption at this point isn't 2025 CAFE, it's the European WLTP+RDE tests making diesels no longer feasible and requiring a real-world improvement in gasoline efficiency - the fake improvement from extreme downsizing and turbocharging doesn't cut it any more.

Basically, the industry-wide cheating - some of it illegal like VW, much of it legal - in Europe, and the response to it by regulators, is what's driving this. "Everything will be electrified by (small number of years)", with 48 volt systems in base model vehicles, is simply necessary for automakers to maintain compliance with European fuel economy and emissions regulations simultaneously.

 

It also depends on what kind of hybrid.

I suspect that a lot of these 48 volt systems could provide gains on par with GM BAS or Honda IMA systems - it's all about the power handling capability, and these systems have that level of power handling capability - 10-15 kW or so.

 

Some of that is because of the poor refinement of many auto-stop systems, especially with automatic transmissions that are expected to creep as soon as the driver lets off the brake. While 2 motor hybrid systems (whether they're power split, serial, or even things like Hyundai's combination of a P2 sandwich motor/generator and a BAS motor/generator) are by far the most refined in this aspect (because they can get the vehicle moving on one electric motor, while the other one is starting the engine), mild hybrid systems like this can still help.

If you can dump 10 kW or so into starting the engine, and get it up to idle RPM quickly, rather than the 200-400 RPM of a conventional 1-2 kW starter, that'll help a lot with refinement of auto-stop systems (and potentially even improve emissions performance, because the engine's much more quickly in a stable combustion region).

In addition, things like HVAC will work more stably if they can be powered off of the 48 volt battery rather than the accessory belt - auto-stop systems currently have to start the engine as soon as evap temperatures reach a point where the compressor is required, whereas this could just keep the compressor going the whole time.

Would I rather see everyone go to a power split system as a minimum? Sure, but this does help things, and apparently it does it relatively cheaply while maintaining familiar driving characteristics. (Myself, I detest stepped-gear automatics - if it's shifting for me, do it continuously variably, damn it - but a lot of people detest continuously variable behavior.)

 

Personally I like the auto stop system, sure it be annoying when somebody cuts in front, because I'm driving 55 in the right lane, minding my own business. I have had the big red brake appear twice because of not paying attention. Also the autostop can be easily over-ridden by simply pushing the accelerator pedal. It's very possible that autostop will become mandatory on all cars in as soon as 20 years. I'm curious what the insurance stats are thus far because of autostop.

 

They also allow for catalytic convertor heaters to cut down on startup emissions, and allow longer engine off periods.

The EV push in China also means some degree of hybridization for an ICE car to be offered for sale.

The 20% or so improvements used for headlines was comparing the system on engines available today to a straight ICE from around 1999.

Any full hybrid will do better, but cost is still a determent to adoption. A full system is still around $3000 more than the ICE model. These 48V systems will add $800 to $1200.

VW announced a few months ago that their start/stop system is moving towards going ICE off on coasting.

We test drove a 2017 Malibu, and the start up with the system is noticable. I can see people turning it off if they see much stop and go traffic. Then others will because they A/C all the time.

Uh oh, terminology confusion.
You are talking about the auto braking systems.
We are talking about auto ICE shut off. Which is at stops only for ICE and mild hybrids. These are becoming standard on ICE by increasing CAFE targets. I know the Equinox, Malibu, and F150 all have an auto start/stop system standard across the board. Hybrids, even mild ones, do it better because they can spin the ICE up faster for start up though.

 

Remember neither nedc or epa is really known on the 2019 a7 due out in europe in the first quarter of 2018. Audi/ 48V - 12kw bas system will give it an improvement on the nedc test despite having more power hungry features and faster acceleration than the outgoing model. That may not sound like much, but this is a high powered sports sedan. Lexus doesn't have an equivalent, but its hybrid system in the LSh only improved its epa combined score by 5%. BMW's activehybrid 7 a competitor also only was 5% better than the non hybrid on epa combined tests. The LSh sold 19 cars in the US in 2016 and the Activehybrid 7 1 car. I believe they were both discontinued that year. That is why audi is not building a hybrid for this type of car. BMW now has a 7 series plug-in that sold 465 units this year. That is the way to go instead of straight hybrid. The added power of the bigger battery allowed bmw to have a smaller more efficient engine that allows it to get 28% better fuel economy when in hybrid mode than the normal 7, and of course much better than that when running on electricity. PHEV or bev look to be much better than hybrid in this type of car;-) I doubt audi would ever recoup even engineering costs on a non plug-in hybrid a7. The a7 looks like it will allow the car to coast at high speeds, as well as look at the car ahead in stopped traffic, and fire up the engine when it moves, so that it is ready when you hit the accelerator.

The prius c provides 20KW to its mgs from its nimh battery. A redesign down to 15KW from a physically smaller and lighter 40 VDC lithium battery with less expensive components, along with silicon carbide electronics may drop the hybrid premium without hurting fuel economy. Some of that money should probably be used to replace the engine with a 1.6L given the 2018 camry hybrid engine treatment of improvements in efficiency and power.

 

I think 48V - bas or clutched small m/g - is the way to go in the power (>250 hp) market versus hybrid systems like in the Lexus RXh and GSh.

But these cars also would benefit more from a phev treatment, even if its mild like the bmw 7 series phev or prius prime.

 

Here's a Fully Charged piece on a Bosch event in which their 48 volt systems were prominently displayed, showing some other applications for them - namely, an electric scooter (the Govecs Schwalbe) and one of Elmoto's bikes, using all of the hardware designed for an automotive hybrid application, but in a light electric vehicle application instead.

That kind of thing almost certainly helps the economies of scale for everyone, and makes it cheaper to implement such lower-power and lower-performance vehicles.

 

OK I'm on track now. Of course, Prius had Autostop 17 years ago. I'm not a Prius fanatic, but the company has been ahead of all the competitors out there.
.

 

And a P0 (accessory drive-mounted, ala this system or GM BAS/eAssist) or P1 (crankshaft-mounted, ala Honda IMA) system cannot propel the car without the engine running - auto stop in motion at any speed is at least theoretically possible (and it looks like there's various regimes where this new Audi system does it), but only if there's zero power demand from the driver.

 

Kudos to all contributors to this thread. The detailed technical discussions by people who really know their stuff is IMHO what Priuschat does best.

In the 1990s I had a VW Golf Ecomatic. A diesel(!) with a manual gearbox, automatically servo activated plate clutch, electric power steering and brake assist servo and full engine auto stop and clutch disengagement at any speed when power was not required.

This could be turned off easily by a switch on a steering column stalk if engine braking was required, or if a quick getaway at a busy junction was needed.

It worked well, except that on mine, the steel support for the clutch actuator developed a hidden fracture, that lead to annoying clutch problems that the dealer failed to diagnose and resolve!

Thoroughly ahead of its time though.

See The Golf Ecomatic Page

Posted via the PriusChat mobile app.

 

And I believe "SSA" (Start/Stop Automatic) was available circa 1981 on the Polo, Golf, and Passat/Santana, too.