Rimac Releases Details On “World’s Most Power-Dense” Battery System

MAR 5 2015 BY TDILLARD 32

…well, “details” may be a little optimistic, but it’s more than we had the other day, when the car was unveiled.  It’s clear, though, Rimac, the mad-powerful and kind-of-coy super-electric-car-and-drivetrain company has collaborated with Kongisegg to make this “megacar” go.  Fast.

Rimac Power Distribution Center

Rimac Power Distribution Center

Here’s what we have, via the Rimac site.

“Geneva, March 3rd, 2015. – Rimac Automobili supplies the world’s most power-dense battery-system and other systems for the Koenigsegg Regera – the world’s most powerful production car.”

The details of the pack:

“The Rimac battery-pack is able to deliver 500 kW of power and to absorb 150 kW during regenerative braking. A standard battery-pack would weigh more than half a ton to deliver those kind of performance figures. Of course, this is not acceptable for a Koenigsegg so Rimac developed a complex Fully Flooded Thermal Management System and a fully machined structural housing in order to fulfill Koenigsegg’s radical requirements. This way, Rimac managed to develop a 9,27 kWh battery-pack consisting of over 3.000 individual parts that is able to deliver 4,35 kW per kilogram in a package that weighs 115 kg and takes only 67 liters of volume in the center of the vehicle.”

Now, just to be picky, we’re not going to run the maths on this pack, but it’s extremely unlikely that Rimac is running any new, magical battery chemistry here, since anything that amazing needs to go through at least a two-year gestation period (testing, validation, etc) before anyone is going to see it implemented in a car, and, well, we would have heard about it.  We’ll concede that this may be the most dense pack currently used in a car, and it’s certainly more dense than your Tesla Model S, since many cars are trading power density for other practicality factors, but to say it’s the “world’s most dense power system”?  That’s a stretch.

We await being proved wrong.  However.  Be advised.  Hybrid battery systems are typically using cells with significantly higher power density than PEV systems, since they need to discharge and charge faster.  A Volt pack, from the numbers that are coming out from independent tests are showing fully three times the power density of a Tesla pack, for example.  What’s likely is that Rimac is pulling cells like the Volt’s and running them more as a PEV application.  So, “world’s most power dense”?  Not even if you restrict that to the automotive world.  Don’t even get us going on the aircraft guys.

Rimac, as you may recall, has a pretty respectable showing of 1,088 horsepower, 3,800 newton-meters of torque (2,803 pound-feet) and over 300 kpm in its own little electric megacar Concept_One.

Here’s the text of the complete release:

Rimac Helps Bring World’s Most Powerful Production Car to Reality

Geneva, March 3rd, 2015. – Rimac Automobili supplies the world’s most power-dense battery-system and other systems for the Koenigsegg Regera – the world’s most powerful production car.

Koenigsegg has always been known for extreme performance and innovation. In their pursuit to push the limits even further, Koenigsegg invented a radically new powertrain concept, called Koenigsegg Direct Drive Transmission or KDD.

KDD enhances performance by combining the advantages of an electric powertrain with Koenigsegg’s cutting-edge combustion engines and thereby removing the traditional gearbox from the equation. As the expert for high-performance electric powertrains, Rimac was the obvious partner to assist Koenigsegg in this ambitious endeavor.

Koenigsegg’s KDD system, invented by Christian von Koenigsegg, uses power-dense electric motors and an innovative coupling system to replace the vehicle’s gearbox. This setup takes advantage of the characteristics of electric motors – high power density, instantaneous throttle response, full torque available from 0 RPM and wide power-band. Additionally, this configuration enables Torque Vectoring, regenerative braking (KERS) and 50 km of emission-free full electric drive.

The Rimac battery-pack is able to deliver 500 kW of power and to absorb 150 kW during regenerative braking. A standard battery-pack would weigh more than half a ton to deliver those kind of performance figures. Of course, this is not acceptable for a Koenigsegg so Rimac developed a complex Fully Flooded Thermal Management System and a fully machined structural housing in order to fulfill Koenigsegg’s radical requirements. This way, Rimac managed to develop a 9,27 kWh battery-pack consisting of over 3.000 individual parts that is able to deliver 4,35 kW per kilogram in a package that weighs 115 kg and takes only 67 liters of volume in the center of the vehicle.

The result is a staggering 1500 hp combined ICE+E power output, 2000 Nm of torque, under 20 second acceleration from 0 to 400 km/h and only 88 kg added weight compared to a powertrain with a 7-speed DTC transmission. The Regera will be handcrafted in 80 units in Koenigsegg’s newly upgraded and refurbished production facility.

The saying goes: “Never meet your heroes. You will be disappointed.” Mate Rimac, Founder and CEO of Rimac Automobili disagrees:” That saying doesn’t apply to Christian von Koenigsegg, who was and still is on the top of my hero list. His work and achievements are a great inspiration and his support and friendship are invaluable for me. To work on such an ambitious and forward-thinking project together with Koenigsegg, is a dream come true for us as a company and for me personally. The Koenigsegg Regera combines Koenigsegg’s engine technology with an innovative electric powertrain in a perfect way to enhance performance. It is a perfect example how technology can improve driving dynamics and enhance performance without compromises, while reducing emissions at the same time.”

Christian von Koenigsegg, Founder and CEO of Koenigsegg Automotive said: “Rimac acted quickly and efficiently and managed to create a suitable battery pack that fitted our demanding needs, specification and packaging constrains. As we enjoy working together and appreciate each other’s technology, Rimac is also looking at integrating technologies developed by Koenigsegg. In a sense, two Davids working together against Goliaths of the automotive world – back to back.”

Working with Koenigsegg is an incredible opportunity for Rimac Automobili to learn from one of the best and most innovative companies in the industry. Both companies hope to further expand their collaboration in various fields.

Categories: Battery Tech, General

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32 Comments on "Rimac Releases Details On “World’s Most Power-Dense” Battery System"

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Ahhh! At last! Some serious competition to stimulate Elon Musk for the Roadster II.

Does any ICE car can go that fast quicker?

Re: ICE
Stock? No.
Mod? Yes. There are 2,000 hp street cars, cars that do 8 sec 1/4 miles. Full roll cage, Tubbed wheelwells and DOT slicks (yes, street legal), some with the ‘chute on them on the street. Old, pre-1973 cars (basically just use the VIN) also have the benefit of being smog exempt.

Despite ICE being less efficient (but EVs also loose efficiency too at high rpms) and hell of a lot more complex to tune or modify, gasoline is just so power dense.

I think we’ll see more of performance modification in the EV world once battery tech improves. People may be going to EV-west and other shops instead of Tesla as an alternative. I predict kit cars with pre-built chassis and pre-configured drivetrain set combos would become as popular as they are in the ICE world.

You may even see tubbed cars like the Assault & Battery EV Miatas on the street.

500/9.27 = 53.9
That’s a hell of a C number for anything short of nanotech lipo isn’t it?

Yes that is VERY high, but that battery would be completely depleted after only 11 seconds. looks like the battery only needs to produce that kind of power for a brief period until the ICE/gen set starts and dumps power to the electric motors.

50C means it’ll theoretically last 72 seconds at that rate, not 11.

A PHEV doesn’t really need more than that. At 200 mph, a 5000 lb car only has 2.5kWh of kinetic energy.

“A PHEV doesn’t really need more than that. At 200 mph, a 5000 lb car only has 2.5kWh of kinetic energy”

Huh? What does kinetic energy have anything to do with the kind of power you need to get there or cruise at that speed?

The kinetic energy is meaningless here since it doesn’t account for the tire drag or the aerodynamic drag at 200mph…

Sorry, I should have been more specific. A PHEV *hypercar* doesn’t really need more than that.

Koenigsegg isn’t trying to save the environment with this car. Their goal is performance.

Double checked your math which is correct, but as MMF states, its pretty irrelevant. Also you assume zero electrical and zero mechanical losses in the car which, having a fast car myself, I can tell you that if you floor the gas, most of the battery will end up in unwanted heat.

That’s why TOP GEAR got their Roadster dead after 55 miles by driving the thing too fast. I’ve seen this happen to my Roadster and the battery capacity eaten up by high-performance really has to be seen to be believed.

Now, someone could probably make this much more efficient. But the cars we have to day, act much more like the number given (11 seconds) than the theoretical number you came up with. Its an interesting number, but it doesn’t practically apply.

Actually, Top Gear never got the Roadster dead. That would have been too much work. Instead they simulated what it looked like, prompting a deserved lawsuit from Tesla, which they ultimately won, because Top Gear is an entertainment show, not a car test show.

That’s sharpening the pencil point a bit too fine.

With all the outrage on these blogs that particular point has been covered ad nauseum.

Yeah, that’s why I said 10 kWh is decent, despite my calcs showing 2.5 kWh. A factor of 4 is pretty good to cover losses.

I know watts is watts; but it just seems like the amps being pulled from the 620 V battery pack would be “less of a load” since it’s not going to be pulling mega amperage.

Imagine a Tesla pack if every cell in it was in series.

“Imagine a Tesla pack if every cell in it was in series”

Assume that Tesla pack has about 8,000 individual 18650 cells. then if you put them in series, you would have about 29,600 volts and only capable of pumping out 30amps at most. So, you would trade high voltage for low amperage…

The particular connections to the cells don’t make any theoretical difference.

The batteries will heat just as much if you draw a certain amount of power from them and it will be the same whether you connect all the cells in parallel for a HUGE amperage, or you connect all the cells in series and its a huge voltage, but the theoretical loss and heating of the collective cells will all be the same.

But that can make a difference when fast charge is concerned because if you increase the voltage you will be able to give a higher power for a same amperage and the directly associated charging cable section. At 400 v that is about 74 parallel circuits, with only 5 parallel circuits you have 5920v which is a much higher voltage but still manageable for high power charging.

That has absolutely nothing to do with my answer. Ryan had proffered that the load would be ‘less’.

Just showing THAT is untrue, it would be the same regardless of the battery configuration.

“A Volt pack, from the numbers that are coming out from independent tests are showing fully three times the power density of a Tesla pack”

Even if that is true, that is still only around 30 C, not the 50C claimed here…

I think most Lithium ion cells can handle more if you can get the heat out. That is the key.

The question is how reliable and durable is this battery at those charging/discharging rate

Most lithium ion cells are not capable of this power density even for short pulse where heat is not an issue.

And the actual discharge C rate must be much higher than 50 C due to voltage sag.

Li-ion battery characteristics are a tradeoff. You can maximize for one characteristic by sacrificing the others.

We’ve seen many reports of lab demos of batteries with very high energy density or power density… but in cells which are worn out in only 10 or so charge/discharge cycles. If that’s what Rimac has done, then it’s nothing more than a publicity stunt. Who would buy a car which can only be charged up 10-15 times before you need to buy a new battery pack?

It’s pretty silly to assume that’s what Rimac has done.

For example, A123 claims 1000 full DoD cycles at continuous 10C discharge, and 100C pulse capability. They’ve advertised this for years. I’m sure others are making similar, if not better, cells.

Remember that this car has a 1100 hp ICE in it, so the pack is mostly going to be doing burst cycles. There’s no doubt in my mind that a decent life is possible in a lower density cell.

This is good reminder why all thouse who complain that electric cars are slow charging are just tech-ignorant and they utterly fail to understand the consept of innovation potential of technology.

Actually charging rate can be increased indefinitely if there is just properly designed cooling system. And properly designed does not mean expensive. Properly designed is just something that is opposite to Nissan LEAF battery cooling system.

Therefore, when affordable long range electric cars are starting to pop into markets in Early 2020’s, we can expect 250 kW to 350 kW peak charging rates. This can deliver 200 km added range in mere 5 minutes or 400 km added range in 20 minutes.

Rimac’s claim is:

“Geneva, March 3rd, 2015. – Rimac Automobili supplies the world’s most power-dense battery-system”

Power density is kW per Liter. Their battery pack is 500 kW in 67 liters of space, or 7.46 kW/l.

This is sometimes confused with specific power, measured in kW/kg. Rimac’s pack is 115 kG, making its specific power 4.35 kW/kg.

Both are very good specifications, and Rimac should be proud of their work.

Density is measured grams per liter, and has nothing to do with Rimac’s claim. Rimac is NOT claiming “the world’s most dense power system.”

GSP

To get 500 kW from a 9.27 kWh pack requires a C rating of 500/9.27= 54 C.

The spreadsheet above that concluded that 20 C was enough has a 25 kWh pack. 20 x 25 = 500 kW. But the Rimac pack only has 9.27 kWh, which requires a 54 C discharge to get 500 kW.

GSP

The inaccuracy here is the assumption in all these posts that the battery will remain 9.27 kwh (3 significant digits, no less!!) capacity at an 11 second discharge rate.

A higher discharge rate will lower the useable output from the battery, unless you consider heat a desirable output.

Its total ‘electrical’ energy output at such a high discharge will be LOW.

Call me back when they’ve invented a practical superconducting battery. Until then, I’m not holding my breath.