Batteries and New Battery Technologies

Thanks Rick,

I could replace 2 x 91mm for 3 x normal size "D" type. in an emergency situation. Thus you would go for the 5 Ah type?
That is interesting. I was always under the impression that it has to be by surface freight. 500 batteries x +/- 200 gram ? 5Ah. = 100 kg. I don't know what the airline would think about this. Was your charged, Rick?
Bert

 

It was partially charged - maybe 20%.

Rick

 

Thanks. Bert

 

Anybody knows this product and where it can be bought? I assume it is quite expensive, because it is only a few grams. (6.5 gram)

http://www.chemtronics.com/products/product.asp?id=197

Capt Vimes, is this the one you had in mind?

Bert

 

Hi Masalai,

What about this one for you. What you save, you spend on LiFePO4

http://www.greendiyenergy.com/index2.php

I have made my own, a very long time ago. The main problem I had, was to solder the cells. You first take some unbreakable glass, glass you can walk on and then you lay your cells out and with a tiny litlle bit of gluegun glue keep them at their place, solder the cells in serial with wire and bring the wires out. (34 please not 30 !!!) Then you use lots of glue. Thereafter you place some of that silver lined heat reflecting stuff (What they use in the cealings) over the cells. Find a way to seal it nicely and make sure you use lots of glue. Bingo, your very own solar battery.

Bert P.S. They don't tell you were to buy broken half cells. It is true, I also used them, may not look as nice, but they give the normal energy per cm2

 

Sorry but I am self financed on a prof's salary, so I always proceed slowly on large orders. That means I would not buy anything without doing extensive research as to quality from various independent sources. I always start with a small, sample order to verify that all dimensions and capacities as well as quality check out. China stuff is particularly suspect in my previous experience- expect defects, out of spec dimensions, delays, no customer service after the sale, and no economical way to return defects or receive missing pieces from a shorted order. If I were in your situation, I would completely build and test a prototype from what ever cells can be obtained locally (even at higher prices) before wasting time and money on something that might fall through.

Please don't take this in the wrong way, just trying to help based on my years of experience.


Porta

 

Hi Porta,

Thanks for your very concerned advise. Yes, it is true, but the problem is that those types are not available anywhere, other than in China or maybe in the USA (I doubt). In anyway I would not have parted with all that money before a more in depth look at this company and references. To tell you the truth I was not planning to part with more than $ 500 and most likely I will only order 60 pieces to do a trial run. Whether they will accept this, is a question mark. But time will learn. I first have to solve the contact problem in anyway. I have only been in Hong Kong, but I have friends who do visit china 4 @ 5 times per year for electronics and was planning to involve them. The reason why I like to see others involved in buying as well, we could then together make some sound business decisions. I do appreciate however your concern. Sometimes one has to make calculated risk decisions. Unfortunately I have better experience with companies from the far east, then with companies from other countries. I have 7 faxes and e-mails on which I haven't even received a reply. I have on all my e-mails and faxes to the far East sent in my life, received, either a short negative or a positive reply. My sincere apology to you, but that is my experience. However I do agree that I have to assume some potential losses in quality, but again it will be a calculated risk and a learning curve.

On a lighter note, Lufthansa still hassn't found her luggage. I told my wife to go out on a buying spree. Will sort the bills out afterwards. I wonder how deep the dent will be in my bankbalance.

Bert

 

Hi Porta,

Would you know of this product and who can help me were to buy this.

http://www.chemtronics.com/products/product.asp?id=197

If it fails and it goes to the home site,
select: your country
select : electronics
click on product >>> you get the overview
click on "circuitworks" TM >>> you get the overview >> go to the bottom
click on "circuitworks - Silver conductive grease

This could be the product I am looking for and could be the long term connection between batteries, even at 4 or 5 Ampere per "cell".

Bert

 

LiFePO4 specs and testprocedures

I received the test procedure and specifications of those type "D" batteries.

The file is quite large, 1,42 MB. The translation with adobe translator has some flaws, but all in all the specs are good. If we have 50 "cells" of each max 5C discharge and the current is drawn via 50 diodes from those "cells" (each cell = 14 batteries in series) the law of the average will draw approx 2 Ampere of each cell at a motor current of 50 Ampere. At 100 Ampere approx 4 Ampere. This is well within the specs.

Please note:
The short circuit at 25 degree and 60 degree, NO FIRE OR EXPLOSION. It certainly gives me the confidence to use them on a boat.
Bert

 

yes - i was thinking of somethng like this..... found a supplier for europe for 35,24 € a tube....
http://www.pkelektronik.com/index.asp?ProductID=579

sorry for answering to this post of yours but the other link didn't work without your description for me...

 

Not a problem,

On my Internet computer it went straight to the correct page, but when I checked on another computer, I realized the problem.

I wonder how much is needed per battery. If I have 700 batteries, the cost may go through the roof. In that case I have to re-direct and use the same batteries but with a soldering slug and just solder the chain of 14 batteries together and then place it into the pipes. I will still be reasonable flexible, but the contact between batteries is then secured. It will just take a little longer to replace a faulty battery. How often will that happen? Not often. This will be thus my backup plan.

Bert

P.S. I found a local supplier, he does not have them in stock, but can order. He has other products from the same company. I was able to locate this supplier due to your link to the German Website. Thanks, it certainly helped

 

i bet they are a lot cheaper in SA.... europe is f**** expensive....
and it is very comforting that the salaries here are comparetively f**** low....

 

Hi , Did you mean Flipping? You may say so !!!
Bert

 

Hi Capt Vimes,

I found it and bought it. Not that much cheaper!.

Hi Bert.

We can get from Farnell in the UK.
Price : R 326.00 ea + vat ( del +/- 10 days )
Farnell Order No: 170-2759
Mnf Part No: CW7100

We also keep the ELECTROLUBE 3gram.
Part No: SCP003 ( spec sheet available from Farnell's web-site )
- supplied in a small bottle
Price: R 171.00 ea + vat

Regards: Gordon

Lets hope the 3 gram will be doing its job.

Bert

 

Hello, just to say the tread is very interesting, and to let you know i am going to china in the next week for a factory visit to 3 of the main lithium suppliers,
personally we are building a 36kw launch running at 300v,
having built a few lithium boats of reasonable power before,(15 to 24kw) it is the management system thats key to performance, and life-span,
one company we are seeing, reckons they have a new system that can take power from one cell and put it in another, constantly balancing the pack,
sounds to good to be true ( hence the visit) but will report back on my return,
one of our boats is on line, see www.pattersonboatworks.co.uk, and look for Elektra in the new boats section