Flybrids

[cootuk]

Looking at Torotrak and Flybrid Systems, there seems to be a good push for KERS flywheel energy capture.

Volvo, Ford, and Jaguar look to be developing systems that should give a minimum 20% fuel economy boost whilst using fairly (cheap?) conventional components rather than large batteries.

I would love to see how these stack up against a Battery hybrid as the cost savings may be quite substantial?

[AEO]

Looking at Torotrak and Flybrid Systems, there seems to be a good push for KERS flywheel energy capture.

Volvo, Ford, and Jaguar look to be developing systems that should give a minimum 20% fuel economy boost whilst using fairly (cheap?) conventional components rather than large batteries.

I would love to see how these stack up against a battery hybrid as the cost savings may be quite substantial?

But a flywheelmust be of considerable weight to be functional?

I think a hybrid will perform better.

[cbcdesign]

Looking at Torotrak and Flybrid Systems, there seems to be a good push for KERS flywheel energy capture.

Volvo, Ford, and Jaguar look to be developing systems that should give a minimum 20% fuel economy boost whilst using fairly (cheap?) conventional components rather than large batteries.

I would love to see how these stack up against a battery hybrid as the cost savings may be quite substantial?

But a flywheelmust be of considerable weight to be functional?

I think a hybrid will perform better.

The Flybrid is supposed to be small, light and powerfull too so it has a lot of potential certainly.

[Sagitar]

Looking at Torotrak and Flybrid Systems, there seems to be a good push for KERS flywheel energy capture.

Volvo, Ford, and Jaguar look to be developing systems that should give a minimum 20% fuel economy boost whilst using fairly (cheap?) conventional components rather than large batteries.

I would love to see how these stack up against a battery hybrid as the cost savings may be quite substantial?

Have a look here

[cootuk]

I can see two disadvantages of kers.

The first is the flywheel will spin down when stationary, the second that air con etc will still need their engines running.

Talking to a few people about the Prius I think most of the general public are still unaware how the Prius operates seamlessly and how reliable the regen side is. Kers could be added to cars without the rhetoric and pack of lies spread against the Prius by Detroit/Top Gear.

[Cyker]

I think they may become complementary techs; Battery systems are mostly used as Prime Movers in things like the HSD, but KERS systems are not designed to be prime movers.

The biggest disadvantage with batteries is you can't dump or pull loads of energy into/out of them quickly as they will catch fire. (This is why current Battery systems have hundreds/thousands of them in parallel to spread the load)

Flywheels (And compressed air) are much better at this, but lack the capacity of batteries (You couldn't drive 200-odd miles on them unlike the Tesla!)

I've seen Flywheels and Compressed air used purely for KERS - There is a Chevy concept car that uses braking energy to compress air in a small cylinder; When you accelerate again, this air charge is used to power most of the acceleration.

As we know, acceleration is where you use the most energy so just having that system in place will save a lot!

[cbcdesign]

I think they may become complementary techs; Battery systems are mostly used as Prime Movers in things like the HSD, but KERS systems are not designed to be prime movers.

The biggest disadvantage with batteries is you can't dump or pull loads of energy into/out of them quickly as they will catch fire. (This is why current battery systems have hundreds/thousands of them in parallel to spread the load)

Not so. You can draw very large currents from batteries in fact, in milliseconds if necessary. Switch tripping applications do precisely that. Charging them takes more time but even that can be done quite quickly if certain conditions are met.

The main reason cells are in parallel is in fact for convenience and ease of connection. It has very little to do with limited current capabilities. You can make single cells in VERY large capacities but they are not very practical in such formats. Victron for example manufacture a 2V 2000AH Battery which can deliver plenty of current but you need 6 of them to make a 12V Battery and that makes the pack large.

Also, the connections become a problem as cables and connectors become cumbersome above certain sizes. This is why higher voltages tend to come into play where lots of power is required. A 600V Battery can have cables and connectors that are 1/100th the size of a 6V battery for the same amount of available power.

[Cyker]

Only if we're talking Pb+ or NiCd/MH batteries; Sorry, I should have clarified I'm talking about the Lithium Ion cells used in most current hybrids.

I know from experience with model aircraft, you typically use NiMH cells in series for extra voltage, but with LiIon you have to use a mixture of series and parallel because they can't deal with high current draws and get extremely hot to the point of being a fire hazard!

High current also kills the Battery really quickly, which is why trickle-charging is seen as much better for a Battery than fast-charging.

Laptops are a good example; They tend to need a lot of power from their packs, and the chargers try and charge them as fast as possible. This is why well used laptop batteries seem to loose a huge chunk of capacity after only a year and are often useless after only 2.

To be fair, this applies to most types of rechargeable Battery! :(

For the LiIon batteries used in the Tesla and HSD, I'm certain the reason for having so many cells in parallel is to cope with the current draw without the batteries degrading badly, otherwise they'd put them all in series and have much higher voltages (As you say; Higher voltages are more efficient!)

I know in F1, they use the bare minimum number of cells to deliver the power they need, and because of this the KERS battery pack has to be scrapped after every race because it's completely wrecked from the high-current charge/discharge cycles.

One thing I haven't seen much about recently has been nano/super-capacitors; I had expected we'd see more of a presence as they can cope with repeated cycles of huge currents and voltages with almost no degradation (Heck, they use banks of them to start nuclear reactions! :D) and would make a great complement for battery-based KERS/hybrid drives!

[cbcdesign]

I think LiIon are more trouble than they worth quite honestly. They are sooooo finicky where temperature is concerned. They cannot be charged if they are too cold, cannot be charged if they are too hot, give me a break! NiMh are far easier to work with.

[Cyker]

Hahaha! I totally agree!

Even charging LiIon to 'real' full capacity is risky as they don't have a delta peak like NiMH/Cd. Ugh... they need so many safety devices because they're so temperamental!

Unfortunately they are still (AFAIK) the highest energy density Battery chemistry we have so we have to put up with its idiosyncrasies...