Batteries and New Battery Technologies

[BertKu]

Originally Posted by FAST FRED

"I agree that Americans got caught up in cheap fuel and big cars about the same time as bad government policy made these cars too inefficient."

The new mandates from the ruler of GM is expected to cause 4000 extra deaths per year.

Efficient? For who?

FF

I assume that you like to stick to big heavy "Jerrytanks" and not help me to make an efficient super capacitor for boats. I also assume that a press release from GM now indicate that, GM will make lighter cars, while you want safer cars. What about helping me with making a very light super capacitor, you can then inform GM to make the car heavier, because the weight of the powersource is lighter. Forget oil, we will run out on the long term.

BertKu

[Submarine Tom]

Forget oil, we will run out on the long term.

BertKu[/quote]

Bertku,

We'll all (Homo sapiens) die before we run out of oil my friend, but I do

hope one day (very soon) we'll look back and say, "What a bunch of

dinosaurs (no pun intended) we were to drive around in hydrocarbon

burning vehicles for so many years."

Tom

[Jeremy Harris]

I'm far from being a boat expert, but I do have a lot of experience with batteries and battery chemistry, so can, perhaps, help dispel some of the myths.

Lead acid has been around for well over 100 years, and we know pretty much all there is to know about how to optimise this chemistry for any application. They come in various flavours, related primarily to physical and chemical plate and electrolyte construction, recombinative chemistry to prevent excessive electrolyte loss and conductivity enhancement tweaks to lower internal resistance. They are all heavy and big for the power and energy output, but are relatively cheap and last a fair time if not abused.

Nickel chemistry batteries come in several types:

Wet nickel iron cells (NiFe) last practically for ever, can deliver high currents, but are pretty much the same weight per unit power/energy as lead acid and use a very caustic electrolyte. Initial cost is high, but their long life may make up for this.

Next in the development timeline comes nickel cadmium. These are capable of high power density and a reasonably high energy density, and can last for at least as long as lead acid cells if looked after. The major downsides are that they are classed as toxic waste (due to the cadmium content) and they suffer from "memory effect", where their apparent capacity drops if they are not regularly fully discharged charged and charged. Few manufacturers make NiCd cells now, because of these problems.

The final type of nickel chemistry cell is the nickel metal hydride. These are a bit better than NiCd cells in terms of energy density, about the same for power density, but have the major advantages of having no "memory effect" and not containing a major pollutant. The most significant downside is the high self-discharge current, left for any time the cells will discharge more quickly than other types. They do have a long calendar and cycle life though, probably the greatest cycle life of any current available cell technology (barring super caps).

Finally, we have all the various flavours of lithium chemistry. All are essentially "lithium ion" cells, most use a polymer ion carrier so are sometimes called "lithium polymer". All have high energy densities, some have high power densities too. There are two main groups, the older cells that use lithium cobalt oxide, or lithium manganese oxide, as the cathode and newer cells that use lithium ferrous phosphate as the cathode. These two groups are quite different in many ways. Lithium cobalt oxide, and to a slightly lesser extent lithium manganese oxide, cells are capable of high energy and power density, but can present very significant fire and explosion risks if misused. It is the development of these chemistries, more than any other factor, that has allowed the boom in rechargeable consumer goods, and the transition of things like model aircraft from internal combustion engines to electric power. They have major downsides though. Apart from the safety issues, these cells start to age and reduce in capacity from the instant they are manufactured. They will lose 10 to 20% of their capacity every year, making their service life short. They also have a limited cycle life, around the same as lead acid.

The second, and newer, lithium cell chemistry, lithium ferrous phosphate, gets around some of the safety, calendar life and cycle life problems of other lithium ion cell types, at the cost of a slightly poorer energy density and a lot worse power density in the main (although some better forms of phosphate nano particle systems equal other lithium power density figures).

Overall, for very long cycle and calendar life NiMH is easily the best. For highest energy density, lithium cells are best, for power density, lead acid may still just have the edge, although it would be a close run thing with some of the better lithium cells.

Finally, the myth regarding Prius true environmental cost versus Hummer true environmental cost is just that, a myth. The report was paid for by US motor interests, was widely discredited as being based an false assumptions and analysed the Prius costs in great detail, whilst only doing a cursory job of the true cost of other vehicles. It was commissioned as part of a wide-spread campaign by non-hybrid automotive manufacturers to try and discredit Toyota, as the surge in the popularity of hybrids and other imported cars, together with the massive technological lead that Japan had in this area, was rightly seen as a major economic threat to the US motor industry.

For what it's worth, I don't think hybrid cars are the answer to the worlds environmental issues, but they are a darned good way of getting much needed investment into battery technology!

Jeremy

[BertKu]

Thank you both, Tom and Jeremy.

Tom, I agree with you. But would it not be nice to get some new technology without gasses or other tricky charging procedures. ??? (or should we carry on with using DOS and 8 bit computers?)

I had a very suprise offer of help from South Africa itself. We have thousands of kilometers and miles of railway lines underground between 1000 and 12000 feet below surface. They are all running on electrics and very heavy lead acid batteries.

I have been given a person and access to all materials and equipment to help me to see whether we can crack the Siemens patent from 1992 - 1995 and that from EEstor in 2008/9.

Sadly, but it seems I don't need anybody's help anymore. Thanks for the chats and jokes.

BertKu

[BertKu]

Originally Posted by Jeremy Harris

I'm far from being a boat expert, but I do have a lot of experience with batteries and battery chemistry, so can, perhaps, help dispel some of the myths.

For what it's worth, I don't think hybrid cars are the answer to the worlds environmental issues, but they are a darned good way of getting much needed investment into battery technology!

Jeremy

Hi Jeremy,
I personnaly, bet on Super Duper Capacitors. It make sense, it is logic , no gasses, long lifetime, relative cheap, safe, much more energy density than any other battery. ( A price of 50 - 64 Dollar each is quoted by EEstor for quantities of > 50.000 and this for 52Kwh at 142 Kg) China quoted me for a 1000 Farad Capacitor USA$ 12 in quantitis of 100. But 1000 Farad is not good enough, we need 100.000 Farad capacitors for a similar price.

Only this long lifetime is worrying me, as some bright engineer will find a method to make the 40 - 50 year lifetime of such Supercapacitors to a couple of years, just to please the automotive industry and battery industry.

Before the American automotive industry kills the Super capacitor battery, I hope that many other people will have come up with similar ideas and processes.

Bert

[Jeremy Harris]

Super caps do look as if they may have substantial advantages for applications that need very high charge rates and high discharge rates, this makes them ideal for hybrid power systems. The problem for non-hybrid electric vehicle/boat use is the lack of voltage stability with discharge, and particularly the non-linear relationship between terminal voltage and remaining energy. To be of practical use, super caps need to be coupled to some form of voltage regulator, which adds significant complexity and a source of added inefficiency.

The energy a capacitor can store is determined by 1/2 x C x V², where V is the terminal voltage and C is the capacity in farads, which shows that energy stored is proportional to the square of the capacitor terminal voltage.

As a worked illustrative example, let's assume that we have a motor that draws a constant 1000 watts (1000 Joules per second) and a super capacitor of 1000 F that is initially charged to 100 volts. The initial level of stored energy is 5,000,000 Joules. In theory this is enough to run the 1000 watt motor for 1 hour 23 minutes, but the voltage changes like this over time:

Initial voltage = 100V

After 10 minutes the voltage drops to 93V

After 20 minutes the voltage drops to 87V

After 30 minutes the voltage drops to 80V

After 1 hour the voltage drops to 53V

Without something to keep the voltage at a fairly constant level the motor will just run slower and slower as more energy is drained from the capacitor, unlike a chemical battery, where the terminal voltage stays fairly constant through the discharge cycle.

Jeremy

[portacruise]

WOW, great information, with similar observations to my hobby experience over 25 years with batteries. What I notice is there is sometimes a difference depending on large and small size and the quality specifications of the battery when built. Noteworthy is that some systems are very fragile as regards charging and discharging parameters. Forgive me my comments below, as I am just trying to add information, not be a jerk. Feel free to comment or correct anything that you know is wrong. I wouldn't want to repeat bad information.

Lead systems:

Discharges below 50% greatly reduce cycle life on lead systems, so you have to buy something with maybe 2X capacity if you want it to last. Undercharging permanently reduces capacity

Ni/Fe:
Good for stationary applications like remote cabins living off the grid where weight and volume are not important and cost/cycle life are.

nicads:
Quality nicads almost thrive on abuse, short of repeated cell reversal on discharge. Full rated capacity is available without affecting cycle life. Extremely high current versions were used to start jet aircraft and for military applications years back. Some of the first satelites used nicads capable of 100,000 cycles and may still be out there working. Still preferred by many in RC. I have some 20 year old "D" cell paks that still deliver 80% of design. Can be recycled to reduce environmental impact- some retailers in USA take them. Greatest cycle life in my experience, still used in TWIKE, I think.

Nimh:
I don't have any experience with auto size nimh, but the off the shelf "F" size and smaller have not had good cycle life in my applications. Sanyo "eneloops" and other LSD designs have very good charge retention times to one year. Not as resilient to deep discharge as nicad and higher internal resistance in general mean not good at high currents applications. Prius charges these within seconds or hours of shallow discharges, so maybe this explains long life in that application? This one seems contrary to your observations, what am I overlooking?

Li:
FINALLY, someone that agrees with my observations! Manufacturers continue to claim these to have the LONGEST cycle life- claiming 2000+! Each Li CELL must have individual electronic monitoring because they are sensitive to even a single charge or discharge limit failure, last I heard.

Do you believe the 2000 cycle life cordless tool people are claiming for the nano technolgy Li?

Prius comments:

AMEN

Disclaimer:

Take me and my observations with a grain of salt. I mean no disrespect to anyone in any of my comments. Just curious and trying to get feedback on my observations.....

Porta

Originally Posted by Jeremy Harris

I'm far from being a boat expert, but I do have a lot of experience with batteries and battery chemistry, so can, perhaps, help dispel some of the myths.

Lead acid has been around for well over 100 years, and we know pretty much all there is to know about how to optimise this chemistry for any application. They come in various flavours, related primarily to physical and chemical plate and electrolyte construction, recombinative chemistry to prevent excessive electrolyte loss and conductivity enhancement tweaks to lower internal resistance. They are all heavy and big for the power and energy output, but are relatively cheap and last a fair time if not abused.

Nickel chemistry batteries come in several types:

Wet nickel iron cells (NiFe) last practically for ever, can deliver high currents, but are pretty much the same weight per unit power/energy as lead acid and use a very caustic electrolyte. Initial cost is high, but their long life may make up for this.
Next in the development timeline comes nickel cadmium. These are capable of high power density and a reasonably high energy density, and can last for at least as long as lead acid cells if looked after. The major downsides are that they are classed as toxic waste (due to the cadmium content) and they suffer from "memory effect", where their apparent capacity drops if they are not regularly fully discharged charged and charged. Few manufacturers make NiCd cells now, because of these problems.

The final type of nickel chemistry cell is the nickel metal hydride. These are a bit better than NiCd cells in terms of energy density, about the same for power density, but have the major advantages of having no "memory effect" and not containing a major pollutant. The most significant downside is the high self-discharge current, left for any time the cells will discharge more quickly than other types. They do have a long calendar and cycle life though, probably the greatest cycle life of any current available cell technology (barring super caps).
Finally, we have all the various flavours of lithium chemistry. All are essentially "lithium ion" cells, most use a polymer ion carrier so are sometimes called "lithium polymer". All have high energy densities, some have high power densities too. There are two main groups, the older cells that use lithium cobalt oxide, or lithium manganese oxide, as the cathode and newer cells that use lithium ferrous phosphate as the cathode. These two groups are quite different in many ways. Lithium cobalt oxide, and to a slightly lesser extent lithium manganese oxide, cells are capable of high energy and power density, but can present very significant fire and explosion risks if misused. It is the development of these chemistries, more than any other factor, that has allowed the boom in rechargeable consumer goods, and the transition of things like model aircraft from internal combustion engines to electric power.
They have major downsides though. Apart from the safety issues, these cells start to age and reduce in capacity from the instant they are manufactured. They will lose 10 to 20% of their capacity every year, making their service life short.
They also have a limited cycle life, around the same as lead acid.

The second, and newer, lithium cell chemistry, lithium ferrous phosphate, gets around some of the safety, calendar life and cycle life problems of other lithium ion cell types, at the cost of a slightly poorer energy density and a lot worse power density in the main (although some better forms of phosphate nano particle systems equal other lithium power density figures).

Overall, for very long cycle and calendar life NiMH is easily the best. For highest energy density, lithium cells are best, for power density, lead acid may still just have the edge, although it would be a close run thing with some of the better lithium cells.

Finally, the myth regarding Prius true environmental cost versus Hummer true environmental cost is just that, a myth. The report was paid for by US motor interests, was widely discredited as being based an false assumptions and analysed the Prius costs in great detail, whilst only doing a cursory job of the true cost of other vehicles. It was commissioned as part of a wide-spread campaign by non-hybrid automotive manufacturers to try and discredit Toyota, as the surge in the popularity of hybrids and other imported cars, together with the massive technological lead that Japan had in this area, was rightly seen as a major economic threat to the US motor industry.

For what it's worth, I don't think hybrid cars are the answer to the worlds environmental issues, but they are a darned good way of getting much needed investment into battery technology!

Jeremy

[BertKu]

Hi Jeremy,

I fully agree with you. But I think that EEstor solved the problem as follows:
One needs a Voltage reference regulator. Somewhere I still have a circuitdiagram when I made one. What it does, it regulates the output voltage by measuring the input Voltage, the pulse is very narrow and repeated not that often. The output voltage has a second large capacitor. When the input voltage drops (i.e. the capacitor start being discharged) the pulse becomes wider and the output voltage stays constant within the designed parameters.

Lets assume that the fully charged capacitor is 40 Volt ( a number of ultra caps in serial) However the output Voltage is 12 Volt. The pulse is narrow and not so often repeated. As soon the 40 Volt drops to 30 Volt. The narrow pulse becomes wider and the output capacitor remains 12 Volt.

The efficiency is high when using MosFets.

What I need to do, is first to make a super capacitor of 100.000 Farad and than to experiment with regulators.

Trust that the above explanation will makes you an enthousiast future supercapacitor believer as I am. If I have problems and the fellow who is seconded to me is strugling, I hope I can approach you for some inputs.

Thanks Jeremy

BertKu

[Jeremy Harris]

Porta,

I've found the same for some older NiCd cells. I have a set of mass plate cells running a portable radio that must be well over 30 years old now, yet are still going strong. Unfortunately I've never had such a good experience with newer sintered NiCd cells for some reason. I've lost count of the cells that have died on me, plus I must have replaced dozens of dead NiCd cells in peoples hand held radios over the years (much cheaper than buying the proprietary "sealed" packs!).

The comment about NiMH longevity was based mainly on the hybrid car experience, where calendar life of greater than ten years, plus cycle life of many tens of thousands of cycles, seems well-proven. Cycle life certainly seems related strongly to discharge depth for NiMH, the Prius only uses about half of it's effective capacity I understand.

Lithium cell life is generally poor, I've found. Claims of thousand cycles plus for older lithium chemistry seems way off, I doubt many go as far a 500 cycles before losing serious amount of capacity. The exception seems to be LiFePO4 cells, where greater than 1000 full cycles seems well proven. I suspect that these will be good for two or three thousand full cycles, but that's yet to be well proven in the field as far as I know.

The need for a complex, and accurate, electronic battery management system for all lithium chemistries cells is a pain, as it adds complexity to what should be a simple and reliable component.


BertKu,

What you're describing is a type of switched mode converter; it sounds to me like a form of charge pump. These can have high efficiency (95% or so is common) but it still adds complexity to what should be a simple power delivery system. To be able to run high voltage power systems, (good from the point of view of low I²R losses) you really need to use a boost type switch mode topology, using an inductor as an energy storage device, to keep the system voltage higher than the capacitor voltage.

I agree that it can work, but I'm not convinced that it's the answer for a pure electric power source. The real advantage of capacitor power storage is the very fast charge time, which is ideally suited to hybrid vehicles, or those that can produce a lot of regenerative power (heavy trucks with regenerative "plug brakes" for example). I'm pretty sure that it's the tight patent control on NiMH cell chemistry that is driving the development of super caps for hybrids. The patents are stopping the supply of cells of more than a few Ah in capacity at the moment, which limits the maximum charge/discharge current.

Jeremy

[BertKu]

Hi Jeremy,

Any details on the patent restrictions for NiMH batteries? That is very interesting that a patent can restrict the outputpower of such batteries.

I absolute fully agree in what you say, but there must be a clever way to stabilize the output voltage of a capacitor. Either in the way we have suggested or maybe a brandnew idea.

I remember when my competitor was strugling in making transistors and had a yield of 23% only. One day some sod invited the production manager to show off our production line. Within 2 months I lost 30% market share. Why?? We first put a "cellotape" on the wafer and thereafter it was cut. Thus picking and placing was easy and fast. The competitor cut the wafer first and was battling to pick and place the cut up chips.

What I try to say is, somebody may have a very clever idea we both haven't thought about. But I love big capacitors, it has potential, even by using it at low current.

BertKu

[Jeremy Harris]

BertKu,

Although I don't always trust Wikipedia, in this instance they have the story pretty well correct. Take a look here: http://en.wikipedia.org/wiki/Patent_...NiMH_batteries

It won't come as a surprise to find that Toyota had to use lots of small capacity NiMH cells, when you read who controls the patents for large capacity cells................

Jeremy

[portacruise]

My impression is there are already existing small scale supercap applications where the output voltage is stabilized. Clock backups for VCRs/computers, standlights- bicycle tail light dynamo backup systems, and maybe some survival flashlights that use supercaps instead of batteries. If that is the case, may be its just a matter of scaling up the concept to power vehicles.

Porta

Originally Posted by BertKu

Hi Jeremy,

Any details on the patent restrictions for NiMH batteries? That is very interesting that a patent can restrict the outputpower of such batteries.

I absolute fully agree in what you say, but there must be a clever way to stabilize the output voltage of a capacitor. Either in the way we have suggested or maybe a brandnew idea.

I remember when my competitor was strugling in making transistors and had a yield of 23% only. One day some sod invited the production manager to show off our production line. Within 2 months I lost 30% market share. Why?? We first put a "cellotape" on the wafer and thereafter it was cut. Thus picking and placing was easy and fast. The competitor cut the wafer first and was battling to pick and place the cut up chips.

What I try to say is, somebody may have a very clever idea we both haven't thought about. But I love big capacitors, it has potential, even by using it at low current.

BertKu

[BertKu]

Originally Posted by Jeremy Harris

BertKu,

Although I don't always trust Wikipedia, in this instance they have the story pretty well correct. Take a look here: http://en.wikipedia.org/wiki/Patent_...NiMH_batteries

It won't come as a surprise to find that Toyota had to use lots of small capacity NiMH cells, when you read who controls the patents for large capacity cells................

Jeremy

Woohw, there we go again. At one stage I was chairman of the solar society here and we had plans on the table to make as an industry solar cells and panels. We have the best silicon sand by Polokwani and we could make it for USA$ 1 per watt, and we made a profit on paper. Electricity was cheap at that time.
Suddenly Shell, BP and other oil companies moved in and took the chair over. Needles to say what happened.

I truly hope that Toyota has a concept whereby maybe it is even better to have small cells than one large battery. Special when a battery has to be "repaired" after a few years of usage. It would teach the big boys a lesson. Any comment on having lots of small batteries combined? apart from 10% space increase? Manufacturing cost would also be cheaper as one can make those smaller batteries on a fully automated production line.

BertKu

[Jeremy Harris]

It's easy enough to use some fairly clever electronics to stabilise the voltage, particularly for very low power applications such as those you've mentioned. However, this gets to be quite complex and expensive for the sort of power levels needed for an electrically powered vehicle/boat.

The only sensible way to do it with present technology, is a switched mode converter. This works in a similar way to the units you can get to run high voltage appliances from car batteries, but with the ability to accept a very wide input voltage range and deliver the sort of high power levels needed. To illustrate the challenge, let's assume that we have a 1000 watt motor running at 50V. Let's also assume that the power converter works at 95% overall efficiency (probably a reasonable estimate).

With a fully charged capacitor at 50V, the converter draws about 21 amps to run the motor at 50V, 20 amps.

With the capacitor voltage down to 25V, the converter draws about 42 amps to run the motor at 50V, 20 amps.

With the capacitor voltage down at 10V, the converter draws about 105 amps to run the motor at 50V, 20 amps.

This is a modest power application, just 1.25hp, but it illustrates well how the converter circuitry has to be designed to run at very high current, even for such a modest power level. The I²R losses also mount up on the input side as the capacitor terminal voltage drops, so practical efficiency almost certainly gets worse as the charge level drops.

My personal view is that, although it's possible to make this sort of system work, it adds a lot of complexity to something that should, in my view, be as simple as a fuel tank, particularly for power levels in the multi-kilowatt region.

Jeremy

Originally Posted by portacruise

My impression is there are already existing small scale supercap applications where the output voltage is stabilized. Clock backups for VCRs/computers, standlights- bicycle tail light dynamo backup systems, and maybe some survival flashlights that use supercaps instead of batteries. If that is the case, may be its just a matter of scaling up the concept to power vehicles.

Porta

[portacruise]

Thanks, Jeremy, I see your point. It would seem to make supercaps viable they would have to exceed the capacity of the best batteries by a significant measure in the first place. Do we even have that as a possibility other than theoretically or maybe in special lab prototypes at the present? Also, it would seem to require special high power electrical recharge stations to take advantage of supercaps ability to charge up instantly. Supercaps probably good for niche uses in auto size EVs maybe as pointed with regenerative.

Did you have any experience with the Zn- oxygen battery systems? Not really rechargable but the Zn can be electrolyzed back at "service" fueling stations. You drop in Zn anodes at each fillup, and drop off the oxidized Zn to be reprocessed. There was supposed to be a weight advantage because oxygen comes from the air and is not carried aboard. Pie in the sky right now with no infrastructure, though.

Porta