## Daimler Will Launch Mercedes-Benz Mild Hybrid S 400 in Summer 2009

##### 17 September 2008
 The S 400 BlueHYBRID with Li-ion battery pack. Click to enlarge.

Daimler will launch its first hybrid-drive passenger car model—the Mercedes-Benz S400 BlueHYBRID (earlier post)—in the summer of 2009. The S 400 hybrid is one of seven hybrid models Daimler announced in September 2007 that will be rolled out over the next few years.

The S400 BlueHYBRID combines a modified 3.5-liter V6 gasoline engine that delivers 205 kW (279 hp) of power with a 120V, 15 kW electric motor and a starting torque of 160 Nm (118 lb-ft) of torque. The combined system delivers power of 220 kW (299 hp) and a combined maximum torque of 385 Nm (284 lb-ft), with fuel consumption of 7.9 L/100km (30 mpg US) and CO2 emissions of 190 g/km.

The S 400 BlueHYBRID accelerates from zero to 100 kph in 7.2 seconds, and has an electronically governed top speed of 250 kph (155 mph). The fuel consumption betters that of the conventionally powered S 350 by up to 2.2 liters per 100 kilometers. CO2 emissions are reduced by 21%.

The S 400 BlueHYBRID is the first series-production model to be equipped with a Li-ion battery. Continental and Johnson Controls-Saft (JCS) are teaming on the pack, with JCS is providing the cells. Continental is the pack integrator and will also supply power electronics: the inverter and the DC/DC converter. (Earlier post.)

The new Mercedes-Benz S 400 BlueHYBRID is based on the S 350, and features an extensively modified drive train. This encompasses a further development of the 3.5-liter V6 gasoline engine, the additional magneto-electric motor, a 7G-TRONIC seven-speed automatic transmission specially configured for the hybrid module, the necessary operating and control electronics, the transformer and a high-voltage lithium-ion battery.

The compact hybrid module is a disc-shaped electric motor that also acts as a starter and generator. The hybrid module also has a start/stop function, and supports regenerative braking.

The lithium-ion battery not only stores energy for the electric motor, but is also connected to the 12-Volt onboard network via the transformer to supply power to other standard consumers such as the headlamps and comfort features. The newly designed battery system consists of the cell block with its lithium-ion cells and the cell monitoring system, the battery management function, the high-strength housing, the cooling gel, the cooling plate, the coolant feed and the high-voltage connector.

The 3.5-liter V6 gasoline engine with variable valve control makes use of the advantages offered by the Atkinson principle, where the expansion phase is longer than the compression phase. The intake valve is kept open slightly longer between the intake and compression phases, which improves the engine’s thermal efficiency while reducing the specific fuel consumption and untreated emissions. A new cylinder head, different pistons and a modified camshaft with different camshaft control increase the output by 5 kW (7 hp) to 205 kW (279 hp) while reducing fuel consumption at the same time.

On rural journeys and on highways, the S 400 BlueHYBRID achieves a further efficiency improvement by moving the operating point of the gasoline engine to produce a lower specific fuel consumption. The extremely high start-off torque made possible by the boost effect of the electric motor gives the driver a strong feeling of powerful acceleration, while fuel consumption and emissions are reduced.

The current converter is located in the space formerly occupied by the starter. As the control electronics heat up as a result of electric currents measuring up to 150 amps, the system is equipped with its own, additional low-temperature cooling circuit.

Mercedes-Benz engineers placed the transformer in the right front wheel arch, where it facilitates the exchange of energy between the 120-Volt high-voltage network and the 12-Volt onboard network, and also allows the option of emergency starting with jump leads if the standard battery should lose its charge. To ensure a consistently high level of electrical efficiency, the transformer is likewise cooled by a low-temperature circuit.

The 12-Volt lead/acid battery is installed in the trunk, and not only supplies the standard consumers but also the monitoring system for the high-voltage components with energy. Because of its interaction with the lithium-ion battery, it is smaller in size and lighter than usual.

Mercedes-Benz developers also adapted the 7G-TRONIC automatic transmission to suit the hybrid drive, with newly programmed software for the transmission management system. A newly developed auxiliary oil pump ensures reliable lubrication of the transmission even during phases when the internal combustion engine is switched off.

This system is managed by the modified high-performance engine control unit. This unit distinguishes between operating conditions such as city traffic, rural journeys, highway driving or slow manoeuvring.

The driver is also able to monitor the status of the hybrid drive system visually. The instrument cluster has a separate, centrally positioned, display showing the energy flow during boost and recuperation phases, as well as the battery charge status.

The hybrid technology of the S 400 BlueHYBRID is equipped with an extensive 7-stage safety concept:

1. All the wiring is color-coded to eliminate confusion, and marked with safety instructions. This prevents assembly errors in production, and makes the regular quality checks easier to carry out.

2. Contact protection for the entire system by means of generous insulation and newly developed, dedicated connectors.

3. A package of safety measures for the Li-ion battery. This battery is accommodated in a high-strength steel housing, and also secured in place. Bedding the battery cells in a special gel effectively dampens any jolts and knocks. There is also a blow-off vent with a rupture disc and a separate cooling circuit. An internal electronic controller continuously monitors the safety requirements and immediately signals any malfunctions.

4. Separation of the battery terminals, individual safety-wiring for all high-voltage components and continuous monitoring by multiple interlock switches. This means that all high-voltage components are connected by an electric loop. In the event of a malfunction the high-voltage system is automatically switched off.

5. Active discharging of the high-voltage system as soon as the ignition is switched to “Off”, or in the event of a malfunction.

6. During an accident, the high-voltage system is completely switched off within fractions of a second.

7. The system is continuously monitored for short circuits.

The additional weight of the overall system is only 75 kilograms (165 pounds), including the comprehensive safety systems. Payload remains unchanged at 595 kilograms (1,312 pounds).

The S 400 BlueHYBRID is produced at the Sindelfingen plant, together with the other S-Class models. The gasoline engine, 7G-TRONIC automatic transmission and electric motor are first put together to form a hybrid module, then delivered to the production line as a unit. The market launch in western Europe is planned for June 2009; China is expected to follow in August 2009 and the USA in September 2009.

If Cobasys had delivered on the NIMH batteries would they have needed all this?: "A package of safety measures for the Li-ion battery. This battery is accommodated in a high-strength steel housing, and also secured in place. Bedding the battery cells in a special gel effectively dampens any jolts and knocks. There is also a blow-off vent with a rupture disc and a separate cooling circuit. An internal electronic controller continuously monitors the safety requirements and immediately signals any malfunctions" Is this the car Daimler is sueing Cobasys over?

It will be interesting to see if the V6 hybrid in a sedan is a good seller. The Honda Accord hybrid was not. I think that maybe Mercedes will sell this where Honda could not because of the upscale nature of the brand. Maybe Acura would have been a better roll out brand for this back then.

It's good that passenger/luggage space is not compromised by a large battery pack behind the rear seat. Considering that customers for such a car are not so price sensitive, MB could consider making this the only gasoline version of this model. In any event, it will be interesting to compare against diesel versions of the S.

The article states... "the S 400 BlueHYBRID accelerates from zero to 100 kph in 7.2 seconds, and has an electronically governed top speed of 250 kph (155 mph)."

So sad that they govern the top speed to 155 mph. Why not govern the top speed to 90 mph? Or 85 mph? If every car sold in USA were governed to 85 mph, imagine how many lives would not be lost.

The article states... "the S 400 BlueHYBRID accelerates from zero to 100 kph in 7.2 seconds, and has an electronically governed top speed of 250 kph (155 mph)."

So sad that they govern the top speed to 155 mph. Why not govern the top speed to 90 mph? Or 85 mph? If every car sold in USA were governed to 85 mph, imagine how many lives would not be lost.

David

7 people a day in the US slip in the shower and die from cracking their head open. If we just banned people from bathing, think of how many lives would be saved.

Hint: let Darwin work it out.

This sounds like the technology that is used in the current Honda Civic hybrid,where the electric motor can only operate in conjunction with the running gas motor...good, but not Prius territory. Richard

Joseph, that would be a good idea if idiots in cars didn't kill other innocent people as well.

Good to see Mercedes employing that German engineering to hybrids. This vehicle won't save the planet so let's hope the technology trickles down to smaller, more fuel efficient models.

@creativforce:

Mercedes recently sued Cobasys over batteries for SUV ML450, not for this car.
NiMH batts pack might not fit in the small space designated in the S400 hybrid.

Essentially what was achieved by adding the hybrid drive to S350 (also with 3.5 L engine), is about 20% improved fuel consumption on average, I guess much more in stop-and-go traffic, and much less (if any) at highway cruising speeds.
The acceleration performance was kept about the same, at about 7.3 sec (zero to 100 kph).
What will be the difference in price (between S350 and S400 hybrid) is not known.

Must be aimed at US market, in Europe they achieve about the same fuel savings (per litre) in diesel version S320 CDI (3.0 L), except possibly in stop-and-go traffic where hybrids excell.

As for the governed top speed, how about ADJUSTABLE governed TOP SPEED, ie limited max speed (for limited time) for new drivers, for previous speeders, for drivers below 21 yr age?

It would be easy to implement for new cars if mandated, via a common programmable interface.
Only police would be able to reprogram the max speed (and check it on the spot), with a special device.

Reasonable speed limits should be 60, 65, 70, 75, 80 mph, for various categories.
Many accidents would be avoided, a lot of lives saved, especially of very young drivers, and also victims of their excessive speed.
In many ways it may be more efficient than current demerit systems and temporary suspensions, provided programmed speed limitation is imposed for longer periods.
Could be used in combination with existing licence control schemes.

Some parents would like to limit speed of their own cars they lend to their teen kids to drive.
Rental companies could do the same with their cars (or part ot them), also other fleet operators.
What is needed is a common, standardized interface, hard to tamper with.
Would be cheap to implement, less than $10 per car, once standardized, the software would be just ported from one model to another, just an extra piece of cable and a connector. Few would be against that, except teen drivers, but their lobby is very weak. @Joseph: et Darwin work it out Just one tiny flaw in your logic: speeding motorists more often than not take others with them. I've never heard that of people slipping in the shower. Love it. Not a fan of heavyweight extravagance, but as this is the first real example for the elegant and simple concept, I am just happy to see it finally. Most of the innovation is in that extra torque converter sized addition. Hope to see more emphasis on storage and generation in following models. Especially as so many ancillaries systems are in use in the heavier classes. Hope this arrangement finds followers. With a 205 kW ICE and 15 kW electric motor, I wouldn't even call this a mild hybrid. More of a souped up start/stop system. Anne, Id love to see i/2 the ice and twice the gen motor. Its important to note however: 385 Nm total and 160 Nm of that is from the 15KW starter motor. Thats quite a contribution! Pleasing to hear that the Mercedes mild hybrid is going into production. The engineering of this mild hybrid indicates that it could in future replace the non-hybrid version as the norm rather than the exception, just like power steering, ABS and airbags in the past. If concerns about energy constraints continue to grow, fiscal policies could increasingly encourage fuel economy and discourage gas guzzlers. "The S 400 BlueHYBRID is the first series-production model to be equipped with a Li-ion battery." The Mercedes S class has been used in the past to introduce new features which are now widely available in less expensive cars. Mercedes has already announced that the E class hybrid will follow. The E-class is sold in larger numbers and is popular as a taxi in many countries; the hybrid version will be particularly suitable for city taxis. In the E class diesel hybrid the engine is downsized from a 6 cylinder to a 2200 cc four cylinder, which facilitates highway fuel saving while the high torque of the electric motor will assist acceleration. http://en.wikipedia.org/wiki/Mercedes-Benz_W111: "The Fintail models were pioneers of the automotive safety feature of crumple zones, which absorb the energies of a collision. The idea for crumple zones came from Bela Barenyi who worked as an engineer for Mercedes-Benz." http://en.wikipedia.org/wiki/Mercedes_s_class: "In 1973, Mercedes-Benz introduced the W116 line, the first to be officially called the S-Class. The arrival of the W116 saw the introduction of much improved passive safety into the vehicle design, with features such as anti-lock brakes and a strengthened vehicle occupant shell. It was one of the first cars to be available with ABS, a driver's airbag supplemental restraint system, or a turbo diesel engine." "In 1981, the W126 introduced the modern airbag, as patented by Mercedes-Benz in 1971, to the world as an additional measure of occupant protection. Other safety innovations on the W126 included passenger side airbags (in 1986), seat-belt pretensioners, and traction control." Crumple zones, ABS, airbags, pre-tensioners and traction control are now available in much less expensive cars. Its important to note however: 385 Nm total and 160 Nm of that is from the 15KW starter motor. Thats quite a contribution! I'm not sure. They are talking about a 'starting torque', not a continuous torque. When you do the math, you'll see it can deliver this torque up to ~900 rpm, otherwise the 15 kW would be exceeded. The ICE can go up to 1000's of rpm without loosing much torque. If the electric motor delivers max 15 kW, this means that the torque at 2000 rpm is: 15.000 / ((2000 / 60) * 2 * π) ~72 Nm. and at 6000 rpm it's ~24 Nm. Actually, maximum torque is not a really useful metric. adjustable top speed for speeders? More people are speeding on residential and city streets than on interstate highways. A governor enacted to limit top speed for people with a speeding citation does nothing to keep them from driving 40mph through a school zone... Nice - an S-Class with 30 mpg average. Now if M-B uses this system with the Bluetech diesel the mileage would go to 40 mpg maybe slightly higher. Of course, if you can spend$100k+ for a car, is the fuel mileage such a consideration? However, it would put you way above the 'greenies' with the Prius!

@hansb:

I fail to see how a 30 or even 40 mpg car would put you way above a 50 mpg Prius.

Anne,
thanks for pointing out the torque drop after start up and take off.
This also suggests that the combined torque cannot be met in combination if we assume the ice meets its max torque at nearer to max power.
I dont know exactly how fast it drops but agree with your point in a conventional device.

@anne and arnold

It may be true that this hybrid system is not much more than a glorified starter motor. However, in city traffic at moderate acceleration a diesel engine rarely goes above 2000 rpm, in which case the torque contribution is substantial. Moreover, the added torque from the motor allows the ICE to run at lower rpm in order to meet the drivers requirements leading to lower fuel consumption. Btw, city driving and acceleration is where diesel engines spew out most particles (visible smoke).

I think there is some merit in designing a system that does not add much cost and take up a lot of trunk space, but actually enables real fuel savings even for at market segment that is not terribly concerned with fuel prices. I think it is quite smart to design a battery that fits into the engine compartment.

If/when this system trickles down to E and C class, the 15 kW/160 Nm contribution would be quite substantial, albeit a long shot from the 100+ mile PHEVs we all want ;-)

My previous car was a B-class (not mercedes!) size which got 8,5 L/100km gas mileage. In that respect I think it is impressive what they can to with this 2+ tonne luxury car.

Impressive - however Mercedes Blue Tech Clean Diesel already betters this efficiency - why bother with hybrids.

The CDI (Clean Diesel) Mercedes models already better 37mpg and 0-60mph in under 6.7sec — why bother with a hybrid that offers less of both? If diesel technology was losing ground to hybrid technologies, I would agree that Mercedes was on the right track with hybrid technologies — but the new Cdi Clean Diesels better this performance efficiency overall — also with 30% less C02 production compared with gasoline powered vehicles.

For US consumers (who have fewer choices with Clean Diesel technology) there is also an alternative to premium models like Mercedes — try driving the new 2009 VW Jetta Tdi - quiet, good performance and EPA mpg of 41 (likely to be higher). I drove Jetta Tdi demo after renting a Prius for a week — the Jetta Tdi drove much more like a "normal" car — as quiet as any gas power car or hybrid (the Mercedes CDI is even more impressive — at a price).

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