Mercedes new ISG system, with 48V lithium battery

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spinningmagnets   100 GW

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Mercedes new ISG system, with 48V lithium battery

Post by spinningmagnets » Jun 23 2019 9:36pm

I'll find some pics and load them. Mercedes crunched the numbers and decided to make a line of "mild hybrid" inline 4 and 6-cylinder engines, that have temporary electric boost to give the 4-cylinder the power of a V6, and the I6 the power of a V8. The I6 now provides 380-lb/ft, 420 HP.

It has a 900-WH 48V lithium battery. The A/C motor looks interesting, I need to find dimensions on it. Rather than run the A/C off of a traditional belt that is connected to the crankshaft, a motor turns it. The steering power assist is also electric, as is the liquid coolant pump for the engine.

As I'm sure everyone here already knows, certain types of motors and generators are very similar in construction, and with a small amount of adjustment to their designs, one device can work well as both a motor or a generator as needed. ISG is Integrated Starter and Generator.

A single thin pancake device is attached to the rear of the crankshaft, and it functions as the starter motor. Once the motor is running, it begins performing the function of the alternator. It also has a third function...when you try to accelerate, it instantly reverts to a motor for a few moments to add electric boost to the crank.
MercedesISG2.jpg (131.31 KiB) Viewed 616 times
The engine also has a turbocharger, but some turbo designs have a small amount of "lag" between pressing the accelerator pedal, and when the added boost of the turbo takes effect. This turbo also has a 48V motor on it to spin it up to it's designed RPMs much faster.
MercedesAC48V.jpg (184.88 KiB) Viewed 614 times
If you look at the split in the case [on the pic above] the A/C compressor is the upper 40%, and the bottom 60% is the 48V motor...coming soon to a salvage yard near you ?...

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Re: Mercedes new ISG system, with 48V lithium battery

Post by Grantmac » Jun 24 2019 12:45am

I've heard rumor of that turbo pre-spool coming for large trucks, but this is the first automotive application I've heard of it. The combination of that plus the ISG should make for some impressive bottom end.

Hybrid tech is coming to rally cars in 2022 and I can foresee a version of the turbo going into them along with a KERS type of energy capture device.

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Re: Mercedes new ISG system, with 48V lithium battery

Post by Deafcat » Jun 24 2019 10:38am

Ah yea, this is actually a feature that many manufacturers could take advantage of, since most of them are using ZF transmissions... They have integrated electric motor into the transmission unit as a modular option:

Dynastart motor:

Hybrid Clutch:

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Re: Mercedes new ISG system, with 48V lithium battery

Post by Lebowski » Jun 24 2019 11:18am

Sounds very much like what Suzuki does, but they have an alternator style device coupled to the motor via a normal belt. It can act as starter, generator and motor, but it all goes through the belt.

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Re: Mercedes new ISG system, with 48V lithium battery

Post by stan.distortion » Jun 24 2019 11:35am

The same thing was used very early on with hybrid designs, around 1910 to 1920 several used a generator/motor between engine and gearbox that also worked as a starter motor. The turbo spooling motor's interesting, was thinking of testing a motor driven turbo compressor section but it would need a huge alternator (or several regular) for decent pressures.

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Re: Mercedes new ISG system, with 48V lithium battery

Post by Hillhater » Jun 24 2019 6:21pm

The latest variation of the many “48v Mild Hybrid” systems anounced several years ago
I believe Audi/VW have some on the market
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Re: Mercedes new ISG system, with 48V lithium battery

Post by markz » Jun 30 2019 4:13pm

The pre spooling of the turbo is interesting, I wonder if Gale Banks has done one, or has tested it out for his turbo's. They spin so fast, 100k+ rpm

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Re: Mercedes new ISG system, with 48V lithium battery

Post by dustNbone » Jun 30 2019 5:06pm

It makes sense to use a motor for initial turbo spin-up.

Turbines are really inefficient at stall, so just getting it moving into the speed range where the exhaust turbine can take over is a huge hurdle overcome.

But once it's spun up and actually compressing air, the amount of input power needed goes up substantially, making driving it with a motor at that point probably not a very efficient option, especially compared to the mostly free energy the exhaust turbine recovers.

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