Batteries and New Battery Technologies

[BertKu]

Originally Posted by pistnbroke

I never had any proplems with electrics/electronics when I did my degrees ....I am trying to put you right .........(_!_)

You did still not explain about the positive electrons ....

O.K., maybe you should first give me some English lessons. Do I have a fan for this capacitor project? Actual we both are wrong. You have only electrons and if an electron is removed/added, the carrier??? (my translation) will become positive or negative. Maybe the attachement will help me.
BertKu

[BertKu]

Hai Pistnbroke

Here you can help me. I try to get people who don't have your and my knowledge to come to the table and come up with idea's. Even if they are not allways boffin's in electrics, you will be suprised what idea's could come forward, if we allow them to express themselves. By knocking them, there maybe somebody out there who has a brilliant idea, but does not want to make a fool of himself and we loosing out.
BertKu

[CDK]

Originally Posted by portacruise

As I recall, welding voltages are in the order of 40v or so? That would be 40 X 120 = 4800 watts/ 750 = 6 horsepower, not enough for the smallest auto. Correct me if I'm overlooking something, or missed your point.

One thing I wonder about with supercaps is how efficient they are in storage of electrical energy aside from their self discharge losses?

Porta

The point is that such technology is available today at reasonable cost. Yes, the voltage is 40-60 VDC because a welder doesn't want to be electrocuted. For an electric vehicle 400 volts seems to be a good value. MOSFETs for such an application cost only a little bit more than the 200 V types used in the welder. At 400 VDC the welder circuit could supply a 60 hp electric motor, enough for a medium size passenger car.

Supercaps for such an application exist on paper only. What is currently available cannot sustain the voltage needed to store the energy equivalent of a vehicle fuel tank, but that is only a matter of time.

[portacruise]

Yes, I forgot that when you buy MOSFETs and such, most times its by current rating for my 24v applications. Then you look at the voltage rating and its much higher than you really need, but of course no harm is done. Often nothing below 50v or so is available, and it is not any cheaper if you do find it.

I'd place supercaps in the niche category, still having some use in large evs. There is much confusion with their ability to deliver a huge amount of power over an extremely short period of time- something perfect for a one shot railgun power supply might be a good application. But their storage capacity will always lag good batteries in cost, size, weight, safety and complexity, IMHO. You just can't go below a pseudo vaccum for a dielectric material even with nanotechnology materials and field and other enhancements aren't likely to add much. But take that with a grain of salt, as there have been freak surprises like high temperature superconductivity for unexpected materials, etc.

Porta

Originally Posted by CDK

The point is that such technology is available today at reasonable cost. Yes, the voltage is 40-60 VDC because a welder doesn't want to be electrocuted. For an electric vehicle 400 volts seems to be a good value. MOSFETs for such an application cost only a little bit more than the 200 V types used in the welder. At 400 VDC the welder circuit could supply a 60 hp electric motor, enough for a medium size passenger car.

Supercaps for such an application exist on paper only. What is currently available cannot sustain the voltage needed to store the energy equivalent of a vehicle fuel tank, but that is only a matter of time.

[Jeremy Harris]

MOSFETs aren't well suited to high voltage, high current, applications. The problem is the effective power rating, due to internal junction temperature limits and the ability of the junction to get rid of heat through the case to a heatsink.

A look through some MOSFET spec sheets will show what I mean. The critical factor is Rdson, the FET on resistance. As the voltage rating increases, so does the Rdson value. As the power dissipated in the junction is proportional to the square of the current times the Rdson value, high voltage FETs lose out to other devices, like IGBTs, at voltages above about 120 volts or so. This is the reason that high voltage, high power controllers use IGBTs, over FETs.

As an example, the most readily available 100V high current, low Rdson FET, the IRFB4110, has a theoretical current rating of 180 amps. It's Rdson is very low, at 0.0045 ohms maximum. However, if you tried to put 180 amps through it, then the voltage drop across it's internal junction at 0.0045 ohms, would be 0.81 volts. The power that the junction would dissipate would be nearly 146 watts, which is massively greater than the device can withstand, even on an infinitely big heatsink.

FETs can be used at very high currents by paralleling them up, but this then adds another problem. As you add FETs in parallel, the gate charge needed to switch them on and off increases. With just a handful of FETs in parallel the gate charge switching requirements get to be so high as to slow down the maximum switching speed. Slowing the switching speed reduces efficiency, not desirable in an electric power application.

IGBTs also have problems, even though they are able to withstand high voltages and high currents and can get rid of junction heat more effectively, as they have a fairly fixed voltage drop when they are on of around 0.6V or so. This means, for example, that an IGBT carrying 200 amps will need to dissipate about 120 watts, which causes a significant efficiency loss. A good example of how this heat generation is managed in practice is the Toyota Prius controller. It uses it's own liquid cooling system, with a separate radiator at the front of the car, just to cool the IGBTs down.

As I mentioned before, just because something is possible doesn't mean that is desirable as a practical energy storage solution for an electric boat.

Jeremy

[CDK]

Originally Posted by Jeremy Harris

As an example, the most readily available 100V high current, low Rdson FET, the IRFB4110, has a theoretical current rating of 180 amps. It's Rdson is very low, at 0.0045 ohms maximum. However, if you tried to put 180 amps through it, then the voltage drop across it's internal junction at 0.0045 ohms, would be 0.81 volts. The power that the junction would dissipate would be nearly 146 watts, which is massively greater than the device can withstand, even on an infinitely big heatsink.

Jeremy

The IRFB4110 is not made to statically conduct at 180 amps, but in a switch mode application with a lower duty cycle, there are no thermal problems.
Imho it is irrelevant which technology will be used for future supercaps; I only wanted to point out that once a reliable storage capacitor has been developed, the electronics to turn the continuously falling voltage into a stable one will not be the problem.

[Jeremy Harris]

OK, poor example, but the principle is the thing I was trying to illustrate.

The bottom line is that FETs are not efficient for high voltage, high current, switching applications, whichever device you choose to use. The current favourite device for operating in this regime is the IGBT, although there are still significant power losses when using these.

When you look at a chemical battery, then compare it with the complex stuff needed to make a capacitor energy storage system work, then it's no contest as to which is simpler. Some may take the view that complex systems on a boat are not a problem. My take is different, I'd want any electrical system to be as simple as possible, as experience has taught me that complex usually means unreliable.

Jeremy

[Guest625101138]

Originally Posted by Jeremy Harris

........ My take is different, I'd want any electrical system to be as simple as possible, as experience has taught me that complex usually means unreliable.

Jeremy

In the early 70s when Philips marketed their first colour TV in Australia they made a big point on how easily all the electronics could be accessed because they had done a comprehensive failure analysis based on component-by-component reliability. It had so many components that the estimated MTBF was less than a year. The panels all folded or slid in and out in a marvelous display of electronic origami. As it turned out they got the estimates wrong and the added mechanical complexity made them expensive; as I recall about AUD800 in 1974 (AUD5800 in today's terms).

I now have a solar powered watch that has a higher active element count than those early colour TVs. I can wear it without much consideration for how it is handled. I would not throw it onto the ground or submerge it in deep water but it has handled accidental bumps and dunkings for 7 years and hopefully it will continue for a decade or more. It always keeps accurate time.

As complexity goes up there is certainly scope for more things to go wrong but it does not mean it needs to be less reliable. It is a matter of the design detail and the level of testing and development.

I would much prefer a 3-phase motor with a DC to AC controller than a brushed motor using a resistance controller. The brushes suffer both electrical and mechanical losses as well as mechanical wear to produce dusty debris. They run at relatively high temperature. Hence I view the brushes as a significant source of problems that are compounding over time and eliminating these provides a huge leap in reliability.

Designing for efficiency with adequate cooling to reduce high temperature and good packaging to seal out moisture are the prime factors in achieving reliable operation with electrics and electronics. Attention to these details, as in my watch and most modern consumer electronics, will reduce failure rate considerably.

I agree that keeping it simple is a priority but complexity is not in itself a cause of unreliability.

Somewhere on the forum there is an argument put that boats should only use hydraulics for distributed power to avoid having electrics. You then ask well how do you start the diesel that drives the hydraulics? And it goes on to who is producing a hydraulic GPS, radar, lights, safety beacon and so forth that a modern vessel requires.

There are many extremely complex devices and systems that work reliably. It would take me a lifetime to even count the number of components required for me to post this message to this forum and yet I expect to be able to do it at will. I rarely give the system reliability a second thought because it just works despite its huge complexity that I know no single person would have a chance of understanding if they spent a lifetime learning. In fact I know for sure that there is no single person in Microsoft who understands how MS Office works.

Other example of complex systems that we take for granted are our own bodies. Massively complex and no one understands how they work but we expect to get about 80 years out of them. Whether it is primarily intelligent design or a prolonged development period is a topic for another forum.

Rick W

[BertKu]

Hi guys,

Unfortunately I disagree with most of you in many statements made by you, except Rick. He got it right. I am making also electronics for underwater hockey and use electronics in properly sealed potted casings. I will never take a household designed product and dive into the sea. But the people who are doing underwater hockey not only do it in Ph of 7 , but also in beach pools with sea water. Refer to my website http://gqrsoftware.isat.co.za

The electronics/radiotransmitters I am planning to throw hunderds of meter of cable away on a boat, will be potted with 2 terminals and 1 pin. The pin allows me to programme it. The aerial is potted in. If it ever fails, I will throw it away, the cost will be only $18. (I make my own pcb's). I use "raiilway" safety software. i.e. if the unit fails, it must not affect the safety of what the item should do and thus the boat. How do I switch the transmitter on/off under water? Simple, with a read switch and a magnet. How do a 12 year old rider align a beam for the horsy showjumping, simple you look through a little pipe and if you see the other pole, you are aligned. simple, effective.( not my idea, but came from somebody who was allowed to speak out. Pistnbroke please note!)

I had to sign a non disclosure agreement and have to sign off. Although I may have only a 5% chance on success, lets recap.

a) Why should a company like Lockheed sign a contract with EEstor and put their name at risk without some gain.
b) Why should a third party company who audit this product, state that the capacitor battery works well, according to specs and put their name at risk.
c) Why can't we assume that this EEstor capacitor may have different discharge curve by having 3 terminals, ground, charging and usage terminal, instead of 2 terminals like a normal battery. Therefore not need all the electronics we are arguing about.
d) Why can't we assume that the production line will be a fully automated one and this will take time to put it together. They are quoting prices for 50.000 units upwards. Instead of worrying that the economy is so bad, that they have to shelve their plans.
e) I have the suspicion that the development in 1996 by the Germans was put on ice because of the oilcompanies. The same with the water engine from Philips. The same with solarpanels. I don't know what made the owner of the NiMH batteries patent decide not to allow to make large batteries with his patent. Politics can be very powerfull.

I love to have super duper capacitors on my boat, while everybody else use that smelly diesel oil, or other dangerous fuel. Waterproving of terminals probably could work and thus I can go back to a normal hull like Rick suggested.

BertKu

[Jeremy Harris]

I'm not arguing against the use of electronic technology, far from it. In fact I've built electric vehicles, and am currently building an electric boat, with three phase brushless motor and electronic speed control.

One thing I've learned from working with high power electronic components is that reliability is only achieved with very careful and conservative design. Doubling the high power component parts count, just to use a capacitor instead of a battery as a power source, doesn't seem to stack up to me, both for reasons of reliability and also cost, volume and weight.

Capacitor energy storage makes a great deal of sense for some applications, no doubt about it. I don't think it makes such good sense for applications that don't need the primary advantages that it offers (very rapid charge times and exceptionally high peak discharge current), especially as even the very best super capacitor technology is way behind the sort of energy density provided by current technology batteries, especially when the added volume and mass of the required voltage regulation systems are included.

I'm a great fan of Eestor and their excellent developments, primarily as I think they will be the key to easing road vehicles over to more effective hybrids with a better electric power bias, which will probably help to wean consumers further away from their love of hydrocarbon fuelled vehicles.

Jeremy

[BertKu]

Originally Posted by Jeremy Harris

Capacitor energy storage makes a great deal of sense for some applications, no doubt about it. I don't think it makes such good sense for applications that don't need the primary advantages that it offers (very rapid charge times and exceptionally high peak discharge current), especially as even the very best super capacitor technology is way behind the sort of energy density provided by current technology batteries, especially when the added volume and mass of the required voltage regulation systems are included.

Jeremy

Here I disagree with you Jeremy on one point (only!), Just because one is a millionair, he or she should spent all that money in one day.
The same with super duper capacitors, just you have the ability to charge and discharge at high rates, does not mean yopu have to do it. The real advantage I see in capacitor technology, it last for years and millions of charge and discharge cycles. Should I ever be on the sea, I don't have to worrie about my flipping heavy lead acid battery having packed up. All what I have to worry about is to charge the capacitor again.

BertKu

[masalai]

BertKu, as a user of batteries and not an expert, I feel that it will be a long while before they (capacitor style) or even the Ni series come into consideration - AGM only got the nod because of their reduced gassing if charged close to manufacturers specs., else I would be using 2v cells as used in forklifts... - - BMPC07 from the "Classic" range http://www.forklift-batteries.com.au/classic-range/ may loose out to M83CHP12V27, from the "Element" range http://www.forklift-batteries.com.au/monoblocs/ just on bang for the buck, 'redundancy', and convenience...

The C3 rate, weight and amp-hours available are very similar...

[portacruise]

Yes, I agree with the concept of using latest advances in technology WHEN they can be reliably applied, Jeremy! But I try to avoid falling in love with any EXPENSIVE brand NEW hammer, because then EVERYTHING looks like a nail. For many of us, being on the water can very quickly turn into a life threatening situation. So I mostly go slowly, using things that have proven dead cinch reliable over the years. But I will experiment with, and substitute newer technology, as lower prices become attractive and reliable models for my applications evolve. Just can't afford large blocks of time or money spent on dead ends. I love to tinker, so IF I can see something new that can be quickly and cheaply modified, then I go for it. That's why I love a community like this, many bright people to point out things I hadn't considered.

I know from experience that my closed can brushed motor will survive at least 30 seconds of being submerged in fresh water. That's because I've accidently dropped one overboard and quickly retrieved several times over the years-no moisture gets inside during that time. I know driving rain and even salt water splashing have no effect- on my motor and casually shielded resistor control and batteries. I know all of these will absorb moderate shock of being dropped on a hard surface from about 2 feet. I know all can be overdriven for 30 minutes when emergency power is required to quickly get back to shore. I don't know about venting, shock, temperature, moisture etc. effects on brushless motors, contols, batteries and how vulnerable the integrated electronics inside are at this point. That's what I hope to discover as I read in a community like this.

Porta

Originally Posted by Jeremy Harris

I'm not arguing against the use of electronic technology, far from it. In fact I've built electric vehicles, and am currently building an electric boat, with three phase brushless motor and electronic speed control.

One thing I've learned from working with high power electronic components is that reliability is only achieved with very careful and conservative design. Doubling the high power component parts count, just to use a capacitor instead of a battery as a power source, doesn't seem to stack up to me, both for reasons of reliability and also cost, volume and weight.

Capacitor energy storage makes a great deal of sense for some applications, no doubt about it. I don't think it makes such good sense for applications that don't need the primary advantages that it offers (very rapid charge times and exceptionally high peak discharge current), especially as even the very best super capacitor technology is way behind the sort of energy density provided by current technology batteries, especially when the added volume and mass of the required voltage regulation systems are included.

I'm a great fan of Eestor and their excellent developments, primarily as I think they will be the key to easing road vehicles over to more effective hybrids with a better electric power bias, which will probably help to wean consumers further away from their love of hydrocarbon fuelled vehicles.

Jeremy

[Landlubber]

Just in case anyone ever wondered if cars could go fast electrically....
http://www.youtube.com/watch?v=lMGom...rom=PL&index=9

They use Zillas controllers, allowing massive 1200A at 360V to the motors.

[Guest625101138]

This one is quicker:
http://www.youtube.com/watch?v=BrHXdM9f13k
Also has Bill Dube and his bike.

Rick W