Batteries and New Battery Technologies

[masalai]

The engine I have, as it had to be installed, batteries, PV panels are open till December-2009/Jan-2010... My little piece of peace (post#773)...

[sigurd]

looks nice! too long thread for me to read, but looking fwd to more pix!

[BertKu]

Originally Posted by Submarine Tom

It's called "silica gel" and it can be rejuvinated by spreading it on a cookie sheet in a 130C oven for an hour. Great stuff, highly hydroscopic.

(Or is it hygroscopic? Anyway, it loves to absorb moisture...)

Tom

Well, I am back again from Cape Town and that silver paint is made in England. I will try it out this week and paint the batteries which were coroded after a week in the salty air.
It is fast drying conductive paint and I am not worried that it will short circuit the battery terminals. Sadly it is not paste but paint. It has a shelve life of 24 months provided it is stored in the refridgerator.

While I was driving I did a lot of thinking and your guys will tell me that I am nuts, that maybe true, but I will not connect batteries parallel without diodes to seperate them. I will try my "audit" system out on charging and discharging of LiFePO4 batteries. But I will not charge more than 90% and not discharge them of less than 30%. I have a fair chance that it will work. The problem is that everybody tries to charge the batteries 100 + % and wait untill they reached the lowest allowable voltage. Yes, then you need highly sofisticated single charge batterysystems. I have NiCad from Varta and after 35 years they are still in perfect conditions, also my Millennium batteries of 25 years. Also the NiMH GP 2,3 Amphr from 6 years ago. Why?, I don't push them till the limit.

The gentleman who will fly to China to see how they let the one battery charge the next battery, I personnally believe, that you do not allow one battery to discharge into another battery. I will use diodes to prevent that. Somehow it will balance the batteries out without all those sofisticated charging methodes, without that it will be damaging the LiFePO4 batteries.

Yes, I am nuts, but lets see whether it will work out. But again, I will use from 30 - 90% and not from 0 - 100% and thereby taking the risk that I overcharge or overdischarge the batteries.

Will let you know how the paint performs.

Bert

[portacruise]

Conductive paint should be better, as it will stay where it is put (unless it peels off and pieces fall between electrodes causing a short). There is also available a silver epoxy that is meant where soldering is not possible which is pretty good for that purpose. I don't know if maintains a good conductive surface if just put on an electrode- but suspect that it doesn't. Grease would not stay put and could possibly move around to bridge the gap between electronics or even the + and - of a cell, causing a short.

There's still a lot we don't know about Lithium cells even though everyone including the auto companies seem to be jumping in with both feet (one small toe in my case). I have seen mention of 3 or 5 year shelf life, loss of capacity if not recharged 100% (like lead systems). Cell balance seems particularly important with Lithium, but even the best BMS cannot compensate to keep cells level with changes in temperature for cells from one end of the pack to the other. BMS electronics are a possible wild card as they age and with stress from heat, cold, and from corrosive salt atmosphere. Toyota seems to have a good system with nimh though.

The old nicad systems were extremely rugged and of much higher quality than the nicads being made today. I also have some that are 25+ years old, still working well, but the newer ones I've used (Black and Decker) don't hold up more than a couple of years. Saw in an automobile posting that Ford is licensing nimh technology from Toyota and that there has already been a great improvement from the original Prius nimh cells that will be used. So nimh is fighting back strong against the Lithium push.

You may not always have the luxury of nursemaiding a battery pack when severe conditions come up at sea or on the road - to keep it between 30% and 90%. Automatic shut off battery protection switches to keep discharges below a certain level mean stranding with possible life threatening consequences. My experience with EV's has taught me to always have a back up plan and spares of everything on board as you're likely to need it....

Thanks for keeping us informed on your experiments.

Porta

Originally Posted by BertKu

Well, I am back again from Cape Town and that silver paint is made in England. I will try it out this week and paint the batteries which were coroded after a week in the salty air.
It is fast drying conductive paint and I am not worried that it will short circuit the battery terminals. Sadly it is not paste but paint. It has a shelve life of 24 months provided it is stored in the refridgerator.

While I was driving I did a lot of thinking and your guys will tell me that I am nuts, that maybe true, but I will not connect batteries parallel without diodes to seperate them. I will try my "audit" system out on charging and discharging of LiFePO4 batteries. But I will not charge more than 90% and not discharge them of less than 30%. I have a fair chance that it will work. The problem is that everybody tries to charge the batteries 100 + % and wait untill they reached the lowest allowable voltage. Yes, then you need highly sofisticated single charge batterysystems. I have NiCad from Varta and after 35 years they are still in perfect conditions, also my Millennium batteries of 25 years. Also the NiMH GP 2,3 Amphr from 6 years ago. Why?, I don't push them till the limit.

The gentleman who will fly to China to see how they let the one battery charge the next battery, I personnally believe, that you do not allow one battery to discharge into another battery. I will use diodes to prevent that. Somehow it will balance the batteries out without all those sofisticated charging methodes, without that it will be damaging the LiFePO4 batteries.

Yes, I am nuts, but lets see whether it will work out. But again, I will use from 30 - 90% and not from 0 - 100% and thereby taking the risk that I overcharge or overdischarge the batteries.

Will let you know how the paint performs.

Bert

[BertKu]

Originally Posted by portacruise

Conductive paint should be better, as it will stay where it is put (unless it peels off and pieces fall between electrodes causing a short). There is also available a silver epoxy that is meant where soldering is not possible which is pretty good for that purpose.
Porta

Absolute true. That stuff is called "Electrolube" and is available from

http://www.electrolube.com

I need a week to see how it performs. But this stuff is definitely NOT hygroscopic.

Bert

[BertKu]

Originally Posted by portacruise

There's still a lot we don't know about Lithium cells even though everyone including the auto companies seem to be jumping in with both feet (one small toe in my case). I have seen mention of 3 or 5 year shelf life, loss of capacity if not recharged 100% (like lead systems). Cell balance seems particularly important with Lithium, but even the best BMS cannot compensate to keep cells level with changes in temperature for cells from one end of the pack to the other. BMS electronics are a possible wild card as they age and with stress from heat, cold, and from corrosive salt atmosphere. Toyota seems to have a good system with nimh though.Porta

I am not so worried about cell balancing, one can at regular intervals take a 18 battery group of a cell, out for maintenance. But shelf life and special if one forget to re-charge the LiFePO4 batteries are a great worrrie to me.

Originally Posted by portacruise

Saw in an automobile posting that Ford is licensing nimh technology from Toyota and that there has already been a great improvement from the original Prius nimh cells that will be used. So nimh is fighting back strong against the Lithium push. Porta

It is such a pitty that the weight/Price is high and the voltage is only 1,2 Volt. NiMH has such tremendious advantages

Originally Posted by portacruise

My experience with EV's has taught me to always have a back up plan and spares of everything on board as you're likely to need it....

Porta

Sure, one must allways have a backup plan, special at sea

Bert

[BertKu]

Originally Posted by sigurd

(bert, what is EMK?)

Hi Masalai, EMK is actual Afrikaans/Dutch. It is the energy which produces a voltage spike when a coil is cut off from the supply line very fast. How faster the cutt-off, how greater the voltage spike and energy.

Sorry I was enjoying myself driving 450km to CapeTown through the dessert without too much traffic. Hence, the late reply.

Bert

[capt vimes]

bert - you might be interested in some new technologies coming our way relatively soon...
http://www.edn.com/blog/1470000147/post/1940019194.html

there is also a different approach to increase capacity found from the tech. university in graz... they do not feature nano-wires but a simple gel araound the carbon kathode and thus increasing the capacity dramatically - 10x is probagated...

[BertKu]

Originally Posted by capt vimes

bert - you might be interested in some new technologies coming our way relatively soon...
http://www.edn.com/blog/1470000147/post/1940019194.html

there is also a different approach to increase capacity found from the tech. university in graz... they do not feature nano-wires but a simple gel araound the carbon kathode and thus increasing the capacity dramatically - 10x is probagated...

The first one seem to be already 2 years old, where can we read some information on the Graz story. To me, it seems to be a more practical approach and faster put into production.
Bert

[capt vimes]

i only found an article on one of the austrian online newspapers today with no reference to further information and details... and it is unfortunately in german...
http://derstandard.at/1256256051528/...ere-Verwendung

nevertheless - it is also about silicium which is in both examples the way to increase capacity....
here a link translated by google...
http://translate.google.com/translat...009-10-29.html

[BertKu]

[quote=capt vimes;312283]i only found an article on one of the austrian online newspapers today with no reference to further information and details... and it is unfortunately in german...
[[/url]

Very interesting. I do speak German and trust that Varta will soon come out with this new technology. Should I freely translate this and put it as a reply?

Bert

[sigurd]

yes, please?

[BertKu]

Originally Posted by sigurd

yes, please?

Freely translated.

New battery generation for long usage

28 October 2009

Researchers at Graz University process silicon for Lithium-ion batteries.

Graz: Modern appliances requires more energy and also the automotive industry is waiting for more efficient stored power.
“ In developing a new generation, new idea’s are necessary. We need new storage materials for Lithium-ion batteries” explained Stefan Koller, researcher on battery technology of the Institute for Chemical Materials at the University of Graz.
Together with the industry and other academics, he has developed a different material to be used for electrochemical reactions.

This new process makes silicon usable for Lithium-ion batteries, in a statement of the Graz University on Wednesday. Its storage capacity is increased by 10 fold higher than the up to now used graphite process. The user can thus expect significant improvements.
The researcher put a silicon containing gel onto the graphite as carrier material. Thereby performs the graphite as the buffer to enable to transfer large volumes Lithium-ions in and out., explained Koller

Silicon shows an approx 10 fold higher Lithium-ions-absorption versus the at present commercial used graphite. This new material can by unchanged life of the battery store more than double the quantity of Lithium-ions. With their industry partner Varta microbattery GmbH, a patent is applied for, for this new process.

Bert

[BertKu]

Well, I had the impression that some of you thought that we were nuts to have 8000 batteries in serial/parallel. To my pleasant surprise somebody showed me a picture of a submarine which has 5000 type "D" batteries and did 480 km under the ice.

I have now more than ever confidence that this project may fly.

Bert

[capt vimes]

Originally Posted by BertKu

I have now more than ever confidence that this project may fly.

Bert

i never had any doubts...

if you are still following your goal, consider taking larger tubes where you could place 4 of the cells in one level...
would have the advantage that with an not too large increase in diameter the length of the tubes would be shortened dramatically...

1 cell diameter 3,5 cm
4 cells placed side by side would require a tube with ~8,5 cm of diameter but the length would be cut down to a quarter....
saving tube material and weight...
best option with a manageable diameter would be 5 cells in one level....