Volvo S60 KERS Hybrid Prototype: Brief First Drive Page 2

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Volvo S60 KERS Engineering Prototype

Volvo S60 KERS Engineering Prototype

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It’s fun, but is it efficient?

Addictive as it is in sport mode, is KERS really a green solution? Volvo says yes. 

The prototype -- designed in conjunction with KERS specialist Flybrid Systems -- can store somewhere in the region of 150 watt-hours of energy. That's about one-third the energy in the very smallest hybrid-electric battery packs.

While that doesn’t sound much -- about the equivalent of 6 seconds of full-throttle boost -- it makes a massive difference to performance figures. 

As Volvo detailed earlier this year, the current KERS system has the potential to reduce fuel consumption by up to 25 percent, because it gives a turbocharged four-cylinder the same performance characteristics as a turbocharged six-cylinder engine. 

Less cylinders means less fuel and less pollution. 

Interestingly too, while great fun on the track, KERS is best suited to city driving, where lots of stop and go driving, combined with overall low speeds means the gasoline engine can turn off completely. 

Driven carefully, a fully charged KERS system of similar size to Volvo’s prototype could easily take you a few blocks in a busy city rush hour without burning a drop of gasoline.

For heavily congested cities with hour-long traffic jams like New York City however, KERS may not work so well. That’s because the system slowly loses energy over time, due to its mechanical nature, taking about 30 minutes to go from fully charged to empty even if no energy has been sent to the wheels. 

A promising future

Volvo S60 KERS Engineering Prototype

Volvo S60 KERS Engineering Prototype

Enlarge Photo

Despite some of its more obvious drawbacks however, KERS seems to have a rosy future. While Volvo is careful to not comment on KERS’ place in future models, its interest in flywheel technology goes beyond a single-year test program. 

In fact, Volvo’s full-scale test was part of a $3 million research project, jointly funded by the Swedish government, Volvo Cars, SKF, Flybrid and Volvo Trucks. 

So far, the results are promising: while Volvo won’t talk price, it assured us that the KERS system was far cheaper than a comparable hybrid-electric system. 

It’s lighter too: at a little over 132 pounds for the entire system and 13 pounds for the 7.87 inch diameter wheel, Volvo’s KERS system could easily be integrated into its existing production line using the same mounting system used for its all-wheel drive and V60 Plug-in Hybrid cars. 

Combined with Volvo’s all-new Scalable Platform Architecture (SPA) -- which Volvo says could shed up to 330 pounds per car compared to previous models -- and Volvo’s commitment to lowering its fleet-wide average CO2 output to under 0.32 pounds per mile, we think KERS will be making an appearance in a production car some time soon. 

But what do you think? Let us know your thoughts in the Comments below.

Volvo provided airfare, lodging and refreshments to High Gear Media to enable us to bring you this first-person report.


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Comments (15)
  1. Any thoughts on how this considerable angular momentum affected handling when it was at full spin?

  2. done properly it should have counter-rotating drums to neutralize that.

  3. Wonder if the KERS vacuum fly wheel could be fitted to the front end of a Fiero using the GM X car steering, independent suspension, differential and constant velocity joints connected to the KERS storage unit. While the rear engine and transmission would remain independently operating. Has Volvo or anyone tried that? What else would be needed.

  4. Great to see you back at GCR

  5. The problem wtih KERS system is that you can't spin it up without driving/braking first. Then once you pull into your garage that spinning wheel is just a waste at that point. Not to mention the gyro effect on the turns or over the bump.

    However, it is more compact and lighter than the typical hybrid system. I am NOT sure this 60,000 rpm high speed wheel will last as long or cost less to service after some signficant miles.

  6. it may be better for delivery vans.

  7. So the first take off in a trip has no energy and the last stop is wasted., doesn't seem like a big deal to me. The only way that would make a big difference is if you literally make a trip with no stops and little speed variation. In which case you picked the wrong technology to save fuel with. Regarding the gyro effect, would it be any worse than the spinning crankshaft, gearbox and drive shafts?

  8. I don't think any of the powertrain parts that you mentioned spin at 60,000rpm. Assuming that KERS system actually holds some power, it will be a lot of momentum that spinning disk holds...

  9. True, but they do have a lot of mass. The article doesn't make mention of the weight of the flywheel, but it does give rpm and power so assume one of the engineers on here can deduce the weight from the other info. Would be interesting to know.

  10. LOL never mind, info was on page 2

  11. As a layman this would appear to be well suited for pickup trucks, capturing energy during braking and helping to get that heavy truck moving again at stop lights? Yes/No?

  12. Actually, it was hinted that a larger system could be used in Busses, where the duty cycle requires lots of heavy stop/start driving. Of course, it could also be used with any existing drivetrain: gasoline, diesel, electric, hybrid...

  13. Since it's fairly light, scale it down a bit and combine it with a regular electric hybrid system. Some components could be shared. Hard braking spins up the KERS, light braking charges the battery (and any ratio in between). Same goes for acceleration. Turn off the car and any remaining KERS motion charges the battery.
    For bonus points: let me plug the car in to an outlet for 30 seconds to spin up the KERS system to 100% before I leave.

  14. Rich, you're right. It could work that way. But in all honesty, I think any smaller and the system would cost more than the benefits it gives...

  15. For full hybrids, I'd reckon that instead of adding a whole new system (and lots of parts, plus soundproofing), it's probably simpler to beef up the electric motor(s) and complement the batteries with supercapacitors for whatever extra instantaneous power is desired.

    A typical bank of supercaps capable of supplying or absorbing 60kW (~80hp) weights only ~20kg (e.g.

    Re pre-charging this KERS: it'd take an ordinary 120V outlet ~5 minutes to deliver 150W*h, which then may be good for roughly 1/2 mile, saving like 5~10 cents in gas.
    I don't think many people would bother to either wait that long, or get some higher-power circuit installed (30s would require 240V 80A), for so little benefit.

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