Use of ultracapacitors for engine starting

[the mad cyclist]

While looking again at the above two links, I came across this:


Using a large capacitor to start a Ford truck. http://www.sunfrost.com/batteryless_car.html


Edit- Sorry this was supposed to be a follow-up to my post in Catweazle’s topic: Electric Shower Heat Exchangers.

[adam2]

I suspect that we will see more of this technology.
The amount of energy stored in a capacitor is very much less than that stored in a similar size battery, therefore no good for energy storeage for off grid homes.
However for engine starting, many kilowatts are needed for only a few seconds, for which ultracapacitors are ideal.
The working life of these units is unknown but probably greater than a vehicle battery.
For some application a battery would still be needed in order that lights, radio, and the like may be utilised without running the engine.

In other cases as noted above, a capacitor alone could serve.

The cost is very considerable at present but should reduce with qauntity production.

[the mad cyclist]

I suspect that we will see more of this technology.
The amount of energy stored in a capacitor is very much less than that stored in a similar size battery, therefore no good for energy storeage for off grid homes.

Would the size of a capacitor be a problem in an off grid system? I can’t think why they couldn’t be buried.

[Pepperman]

I believe it's more to do with the way they deliver power which is much quicker than a battery? Could be wrong about that though.

Of course if EEstor have actually cracked it in which case we will see low cost, high cycle life off-grid applications in a few years. In fact if EEstor have cracked it then all our transportation problems are solved too.

But then I'm not holding my breath

[adam2]

I suspect that we will see more of this technology.
The amount of energy stored in a capacitor is very much less than that stored in a similar size battery, therefore no good for energy storeage for off grid homes.

Would the size of a capacitor be a problem in an off grid system? I can’t think why they couldn’t be buried.

It is not just the dimensions of the capacitor bank that are a problem, but the costs.
Qauntity production should reduce prices, but I doubt that they will become affordable for bulk energy storeage.

In the example above, the capacitor has a capacity of 150 Farads.
One F can supply 1 amp for one second, for a voltage drop of one volt.
If we start at 14 volts, then 150F will supply one amp for 150 seconds, for one volt drop in voltage, i.e. down to 13 volts.
If we allow 4 volts drop in voltage, from 14 volts down to 10 volts, then the 1 amp load can be supplied for 600 seconds, or 10 minutes.
A vehicle battery could supply one amp for a couple of days.

[the mad cyclist]

I wonder how practical it would be to use very large voltage drops?

[adam2]

I wonder how practical it would be to use very large voltage drops?

By use a switched mode power supply a very wide range of voltages could be accomadated, but the gain would be fairly limited.
In the example given above, about half the energy has been already extracted thereby limiting furthur gains.
The first volt of discharge gives 13.5 X of energy
The next 3 volts of discharge give 12.5, 11.5 and 10.5 X each.
Therefore discharging from 14 volts to 10 volts has released 48X of energy.
The next 6 volts of discharge would give
9.5X, 8.5, 7.5, 6.5, 5.5, and 4.5X of energy or another 42X in total, less losses in the electronics.

[the mad cyclist]

By use a switched mode power supply

Well if you remember, I love those switch mode power supplies.

[thecoalthief]

This looks promising.
http://news.cnet.com/8301-11128_3-20022639-54.html

[the mad cyclist]

And this from technology review.

On the other hand, EEStor's system--called an Electrical Energy Storage Unit, or EESU--is based on an ultracapacitor architecture that appears to escape the traditional limitations of such devices. The company has developed a ceramic ultracapacitor with a barium-titanate dielectric, or insulator, that can achieve an exceptionally high specific energy--that is, the amount of energy in a given unit of mass.

For example, the company's system claims a specific energy of about 280 watt hours per kilogram, compared with around 120 watt hours per kilogram for lithium-ion and 32 watt hours per kilogram for lead-acid gel batteries. This leads to new possibilities for electric vehicles and other applications, including for the military.

"It's really tuned to the electronics we attach to it," explains Weir. "We can go all the way down from pacemakers to locomotives and direct-energy weapons."

The trick is to modify the composition of the barium-titanate powders to allow for a thousandfold increase in ultracapacitor voltage--in the range of 1,200 to 3,500 volts, and possibly much higher.

EEStor claims that, using an automated production line and existing power electronics, it will initially build a 15-kilowatt-hour energy-storage system for a small electric car weighing less than 100 pounds, and with a 200-mile driving range. The vehicle, the company says, will be able to recharge in less than 10 minutes.
http://www.technologyreview.com/business/18086/page2/

[Catweazle]

I like the idea of a big capacitor driving a starter motor, charged by hand-driven dynamo. This would allow a vehicle to run without a battery, requiring just 5 or 10 minutes hand-cranking to start, ideal for tractors and other occasional use vehicles.

[adam2]

I like the idea of a big capacitor driving a starter motor, charged by hand-driven dynamo. This would allow a vehicle to run without a battery, requiring just 5 or 10 minutes hand-cranking to start, ideal for tractors and other occasional use vehicles.

Agree entirely, as oil depletes, tractors and the like wont vanish but will have to be used much more carefully.
Limited use is liable to result in a discharged or defective battery, capacitor starting has much to commend it in such circumstances.
The capacitor could be charged by hand as suggested above, or by a small PV module, or by a small and easily carried battery.