Batteries and New Battery Technologies

Discussion in 'Boat Design' started by brian eiland, Mar 28, 2008.

  1. BertKu
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    BertKu Senior Member

    No sigurd, now it starts becoming a nice heated conversation.

    CDK and me are both thinking negative.

    Me, because I do not think the oil industry and some investers in the automotive industry like, engine builders, will allow anybody to come up with some new battery development which will have, let say 1,5 x the energy of 1 liter of Diesel, petrol, gas etc. They will buy up the patents, they will bribe Obama, twice as much as they have done Bush. I am expressing my personal opinion here. In your terms it means" Lobying the governement".

    CDK thinks negative, because that is just him.
    I mention, conductive paste, he says impossible, I proved it by giving the name and source were to buy it. I buy LiFePo4 batteries and he hints that it is most likeley electrolytic capacitors, I prove it with copies of the e-mails to the supplier. etc. etc. CDK , you are an exellent thinker and writer and I wish that you would be willing to turn that energy into positive development of making a new type of battery. CDK, There are truly people who do develop and are making new inroads of new battery technologies.

    But lets philosophy what would happen if somebody would create a super battery, superior than any other battery. A battery which could be build within a few months in mass production of millions per month.

    First at all, the sales of diesel, gas, petrol will drop and all those pensioners who have put their money into gasoline supply stations would loose out The oil companies collapess, Obama will bring his soldiers back from Middle East.

    There is no need anymore to grab the oild fields. The rest is all a smokescreen. Maybe he would transfer the soldiers to Zimbabwe, were the poor people are in a bad shape, but lets make it clear, the Americans don't drink tea, and that is all what Zimbabwe has to offer. Tea leaves, not oil.

    Some clever entrepeneurs will make a conversion kit for every car to convert to electric motion. some 50 Kw with 300 Kwh battery bank.

    But unfortunately, it takes 10 years before more Atomic powerstations could be put into operation. That is also, what it takes to build more 500 Mw - 2 GW powerplants. How are we going to charge all those batteries from? Solar ? wind?

    Thus, Sigrid, CDK and all others, the moral of the story is, why don't we just make a powerfull battery for the yachting industry, at least we will be left alone by the big boys. Masalai, would we both not be very happy !!
    Masalai, what about making your boat also with some folding up solar panels!!! Maybe solar energy is not that crazy to pursue. A solar-cell-battery just for the yachting industry. The solarboat on the second photo (solar2) operates already for 9 years in Australia. It is an Australian patent.

    Have a nice New Year and that we all may have fun in 2010.
     

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  2. CDK
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    CDK retired engineer

    The incredible A123 battery.

    Sorry Sigurd, I overlooked your post.

    The datasheet for the ANR26650 gives an internal resistance of 10 mOhm, excellent for a 2.3 Ah cell.
    Unfortunately it is immediately followed by the word "typical" and a guaranteed value is not given.

    As usual, the Ri is only valid for a fully charged cell and during 1 second with a 10 Amps load.
    The discharge graph shows a voltage drop of approx. 0.7 V at 40 Amps, so then the Ri is already 17.5 mOhm.
    The useful capacity is 2 Ah because that is where the graph drops sharply.
    Because this is only a small cell, I translate 2 Ah to 120 Am(inutes). It can deliver 40 Amps @ 2.6V for exactly 3 minutes.

    Although the sheet says that 70 Amps continuous discharge is allowed they didn't draw the line for that load because it would surely be well below 2.5 V and wouldn't reach the 120 Am point. The pulse discharge characteristics at 120 Amp I estimate to be well under 1.5 V within 10 seconds.

    All data is based on average values for a brand new battery, nothing guaranteed. At a modest 5A discharge rate, the capacity has dropped to 80% after 600 cycles. That seems to be an acceptable discharge rate for this battery: can keep that up for 24 minutes @ 3 V minimum when new.

    Conclusion: This battery performs more or less like 3 NiMh 2500 mAh cells in series but weighs only 70 grams (NiMh = 90 grams), so for an airborne application they would be first choice.
    But is this a breakthrough? No, absolutely not! The NiMh cells can happily supply 5 Amps for 24 minutes while staying well above 3 volts. In US$ at the current exchange rate, they cost $0.83 each and are available in supermarkets in most European countries....
     
  3. CDK
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    CDK retired engineer

    Bert, I sometimes do my very best not to be negative, but believing was never in my nature.
    How far are you with the LiFe battery bank?
     
  4. BertKu
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    BertKu Senior Member

    Well CDK, You may not believe, but I believe you are an excellent electronics man. no doubt, and we certainly hope to tap into your vast logical knowledge.

    I screwed my development computer up and I am strugling for days now to get it working again. I am getting "Disk error". You know what that means for me.

    I bought some microchips PIC24 and a development board DM240001 and figured out that the brushless motor development board was forgotten by me. Will have to wait untill New Year. Also I need some very powerfull MOSFETS , any suggestion on type number something like 60 - 100 Ampere 80 Volt?

    I ordered from New Zealand the Hartley Flareline 18 boat design. I got excellent service from them. Also ordered a 2,1 Kw brushless motor (474 gram !!!!!!) Do you believe this?? from HobbyCity. Just to experiment with brushless motors.

    The battery bank is fine, I used shrink sleeving for keeping unwanted dirt from creeping between the cells. Also I bought 2 meters of 50 x 25 mm rubber tape. I cut it up in 25mm pieces and they are my springs between my top rubber stop and 1st battery cell. To avoid movement between the pvc pipe wall and the LiFePo4 cells, I use drinking straws to buffer any vibrations.

    I have solved in this way, all arguments from all the readers. Shock, dirt, pressure, movement. etc. No, I am quite happy with the batterybank, but will definitely not buy for Rand 60.000 more LifePO4 batteries. Will stick like Masalai with old fashion sealed LAB's , cost only Rand 6000. Will not use troqeedo's motors. also too expensive, but will have to come up with some design for brushless motors.

    Hope everybody had a nice Christmas. I did, it was, even on the water, some 28 degrees with blue sky.
     
  5. BertKu
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    BertKu Senior Member

    Solar Panels

    We all know that, we can get only 26% Photo Volaic energy from 1 square meter under laboratory conditions. i.e. per square meter is a 1000 watt and we will only be able to get 260 watt.

    But in the real world, we will only get between 14 and 16% i.e. 140 - 160 watt. There are a few tricks to get 18%, but than it gets very difficult.

    If we could thus enlarge that 1 square meter solar panel with reflecting the photons via mirrors onto the solar panel, and we would build 2 square meter of reflecting mirror stuff, which does not let the photons go through, we should be able to get 300 watt out of that same square meter solar panel.

    Unfortunately, I have to build the boat first (refer the Flareline 18 feet) http://www.hartley-boats.com/flare18.html and cannot test this theory.

    Anybody out there willing to try it out?

    Lets be realistic, 2 square meter of mirrors is much cheaper than a solar panel of the same size. Yes, we all have space problems, but maybe folding up mirrors would be a solution? The reflector is not allowed to let the photons go through !!!

    First I thought, a plastic panel with half ball lenses would help, but that will only focus the photons, but does not add extra photons to the panel.

    Anybody on the southern Hemosphere who is quickly willing to try it out? In the Northern Hemosphere, they have only snow and rain.
     

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  6. BertKu
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    BertKu Senior Member

    I am naughty now, but Lufthansa did find the suitcase after 6 weeks, everybody was flabbergasted, just because I took some photo's at home, before she boarded the plane. Much easier to find a lost item from a photo.
    Lufthansa paid her not only all her expenses, but quite some extra for all the hardship she had. Moral of the story, make a photo from your luggage before flying.

    bert
     
  7. JonathanCole
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    JonathanCole imagineer

    More complicated that it looks!

    Hi Bert,

    The problem with what you are proposing is that it is founded on incomplete information. Flat solar collectors will harvest photons most efficiently if the photon's path is 90 degrees incident to the flat collector surface. This would happen at noon on a horizontal (in two axes) collector on June 21 (approx) in the northern hemisphere and Dec. 21 in the southern hemisphere and then only on a cloudless, unhazy day. Any other conditions will require a tracker to keep the flat panel perpendicular to the sun. Of course on boats, since they are constantly rocking and rolling, this is not really practical. In any case, the durablity of such tracking mechanisms at sea is poor. Therefore it is always more cost effective to add more flat panels than to add tracking mechanisms. But to do that, of course you need un-shadowed space to mount them. This means a relatively flat roof. It also means that such flat panel collectors can not be optimized on sail boats because the shadow from the sail is constantly changing. And by the way, the idea of mounting panels on sail surfaces is not a good one because such panels will receive a small fraction of the light that they get when perpendicular to the suns rays. Focusing collectors like your half ball (hemispherical) concentrators can only work when they are not moving. A hemispherical collector focuses light on a line and not a spot, so the photovoltaic devices would have to be arranged around the focal line. Other types of concentrators also do not work well on a moving boat. However, the idea of reflecting additional light onto a flat collector, let's say when on flat water while moored has merit. You could use a stretch mylar blanket or sheet. But remember that the sun is constantly moving so the angle of the sheet will have to be frequently adjusted.

    Generally speaking, flat plate collector panels can have 2 suns concentrated on them without too much problem. But they will have to dissipate more heat, so plenty of ventilation is required.

    Jonathan
    http://www.lightontheearth.org/
     
  8. BertKu
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    BertKu Senior Member

    Hi Jonathan,

    Thank you, input very much appreciated. I was actually not thinking of a tracking device at all, but merely saving money for all of us, if we are aware that reflecting can help. Your input confirm my thoughts and let see whether other users cannot do some "Reflecting" and maybe come up with an idee we haven't thought about. I am more thinking about my own problem as I want to make my boat an electric (headache) boat. Thus any extra watt is welcome.

    Thanks, I am not worried about heat if one makes his own panel. Aluminium, glass, PhotoVoltaic cells can handle 200 degrees. It is just the soldering and any plastic used must be of high standard. Shrink wire can handle reasonable temperatures. Indeed one should find out from the solar panel manufacturer what was used in their product, before shining twice or three times sun energy on their costly solar panel.

    Hope you had a good time during the festive season.
     
  9. JonathanCole
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    JonathanCole imagineer

    Hi Burt,

    Happy new year to you too!!

    One concern of reflecting additional light, however, is that photovoltaics become less efficient, the hotter they get. I believe the optimal temperature is below 120 degrees Fahrenheit.

    Making your own panels is possible but difficult. Hundreds of solder connections to very narrow trace conductors. It is very easy to break the cells or the connections. Then, they need to potted in a clear rubberized material that will not darken in response to infrared or ultraviolet light. It can be done but it is an extremely labor intensive project requiring great care and skill. If you calculate the cost of a ready made panel with the likely time and materials cost required to build one from scratch you will probably be valuing your time at about $1 an hour.

    Cheers,

    Jonathan
     
  10. BertKu
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    BertKu Senior Member

    Yes, indeed, the silicon characteristics will change at higher temperatures. However, I was more thinking in "Double sided tape solution" i.e 2 panels mounted against each other and then a reflector reflecting it against the bottom one. Only PV panel manufacturers will be able to tell us whether there is a cost advantage. (like on my sketch on thread 800)
    When I made a panel (some 25 years ago) I vacuum sealed the contacts to each other instead of soldering it. The panel was not that big, made of rejects half cells, 36 of them and I placed a plastic sheeting at the back and slowly with a vacuum pump sucked the air out. I had to do it a few times, as the connections moved. But it did work at the end. I used it to open my gate, as it was only powered by a battery and this homemade solar panel.

    I do know that some manufacturers put 2 layers on top of each other. The first layer catches the photons in their fork conductors. The second one catches the photons which misses the fork and get collected on the second fork. I have no idee, what the efficiency is of such panel, probably 20 - 22%.

    I found a small solar panel and will do some experiments, and see what I can come up with. It is only 8 Volt and 15 milli ampere, but the principles of reflecting can be established. I forgot about it, that I still had something like this.
     
  11. CDK
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    CDK retired engineer

    Photovoltaic output vs. temperature.

    With increasing temperature, the efficiency of solar panels drops.
    My personal experience is with Siemens mono-crystalline cells, but there is no indication that the inferior technologies like vacuum deposit will not suffer from it. As with all semiconductor junctions, the leakage current rises with temperature, more so if the material is heavily doped or contaminated.
    The silicon wafers used for photovoltaic use are far less clean than those for integrated circuits (except for the cells Nasa uses).

    When I developed a computer program to predict power output for fixed installations in Europe, Siemens solar systems supplied me with lots of data from existing arrays. It showed that the best performing installations were those positioned at bearings between 150 and 170 degrees. They receive more morning light so have lower mean cell temperature. Although they didn't receive the radiation at a 90 degrees angle when the sun is at zenith, the average output was better.

    Recently I drove through Slovenia and saw a building with a large solar array with pivoting panels. The top of the panels could rotate only, the bottoms were connected to a row of short levers that both rotated and lifted the panels. All were connected to a long spindle with a small gearbox and electric motor. Not a real tracking system but one that lines up the panels to obtain a better output than a fixed installation. Only a few panels had a stainless steel mirror, each with a different design, so I think this is an experimental system.
     
  12. BertKu
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    BertKu Senior Member

    Hi CDK, Nice to have your vast knowledge on this topic.
    Do you mean that the inferior technologies may not have the disadvantage of an higher leakage current, then the mono crystalline cells?

    Did you get also the data of the Telkom Betty's Bay Siemens installation here by Cape Town?. That was the first installation we did, with the worst condition selected as a testing site. Always fog, it was between the mountains and only a few hours sun per day. It is still working fine. The real problems we experienced was the birds droppings on the panels.

    Any chance to have a sketch made by you of what you remember of this installation?. maybe we can learn from it. Special the stainless steel reflectors. Thus, reflectors is a solution!
     
  13. CDK
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    CDK retired engineer

    No Bert, they supplied data from the Sinai desert in Israel, several TV and communication transponders in the Alps and from their test site near Toledo in Spain.
    At the time I knew of course there was a southern hemisphere too, but somehow the European industry did not include it in their research.

    I will explain a friend who lives in Slovenia what I saw and where exactly, so he can take a few pictures. The installation is new and looks quite spectacular, so he will have no trouble finding it.
     
  14. BertKu
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    BertKu Senior Member

    Hi CDK, We did that installation some 25 years ago, I assume it was before they put this report together.

    That would be very much appreciated by many boat users. Thanks if you are willing to do that.
     

  15. BertKu
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    BertKu Senior Member

    Actually, I was a little disappointed when I did some primitive test today at 18h15 with the sun shining brithly over the low horizon.

    The good thing is, indeed you can raise the Voltage and thus still charge your battery a little longer. Most boat owners have their solarpanel mounted on a fixed place and in a fixed position. By shinig the sun via a mirror onto your solar panel, you will increase the Voltage and therefore will charge your batteries a little further. You, yourself have to figure out how to mount the stainless steel mirror or any mirror for that purpose.

    The bad thing is that I excepted to have the shortcircuit current to double, by shining a mirror onto the small solar panel. That was not true. It only raised the current from 108 mA to 116 mA and the Voltage from 15.15 to 16.20 Volt. (open voltage) At noon I will be able to compare.

    Tomorrow at noon, I will do again the same test and see what the difference will be. But my conclusion is already to have a stainless steel mirror at hand. You will prolong the charging.
     

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