Batteries and New Battery Technologies

[BertKu]

Originally Posted by PBW

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

That is indeed vey interesting. Trust that you have a fruitfull visit. Any chance to be cheeky and ask your 3 suppliers what they think of Everwin Tech No Limited. Specific about their quality. I have a good impression about them, but need all help to take the jump and place an order with them. It is the language barrier what is probably my biggest concern. I work with a computer translator and they probably also. Appreciated, when you come back with some good news for yourself, to share this with us. I think Rick will also be very interested.


In horspepower, your 36 Kw electric is comparible to +/- 120 Hp if I am right. That boat will move fast.

Bert

[BertKu]

Hi PBW

No objection if you discuss this concept with those 3 suppliers and see what they think about it. Whether they give the tumb up.

a) modular in power size and voltage
b) standard type "D" batteries or cylindrical batteries
c) conductive paste between batteries if needed

Attached 2 more photo's
One showing the bottom with the inter connnections
One showing the top with the rubber feet or rubber balls

bert

[sigurd]

Originally Posted by masalai

In keeping with the "tongue-in-cheek" mood to hide the truth and any pretence at qualified knowledge on my part.... - - How about terminating the wires to a pair of 1" wide and 1/8th" thick copper bars and fitting a neat bolt hole in each so, at a fixed base with a bolt, and a spring washer with a wing-nut, you could hold the bars electrically together simply and effectively... One could even paint the matching ends red and green respectively, (so the + and -/earth? could be correctly paired), over the shrink wrap on the tinned copper cables - - - - Am I useful sometimes (don't answer that)

so that is where my tongue was. I thought the cat had taken it.
douesn't sound either waterproof or super quick, but seems solid.

[masalai]

I was more, - think "waterproof"? - and - "the Titanic did not sink" - - - so how about a robust workaround where the "water" in small occasional droplets, does not have significant immediate adverse impact, and the join mechanism is relatively straight forward and quick to effect (when putting on a trailer and going home)... and regularly wipe the exposed areas with 'petroleum jelly' (Vaseline?)

Glad you found your tongue, and that it was not "the cat" as that would have been very painful and possibly give you some nasty disease...

[sigurd]

bertku, how about filling the pipes with oil? thermal equalisation and conduction, no corrosion.

seems right on, those chinese D or 3/2 D you found. For me the operating and storage lower temp limit is too high. I also note that the measured 1000 0.5C cycles reduced capacity to 70% not 80% as is more common.
Also, lipo / lico chargers are not allowable (unlike with some other LiFePo, I heard) because they terminate at 4.2v and these cells at 3.65.

[sigurd]

Originally Posted by masalai

I was more, - think "waterproof"? - and - "the Titanic did not sink" - - - so how about a robust workaround where the "water" in small occasional droplets, does not have significant immediate adverse impact, and the join mechanism is relatively straight forward and quick to effect (when putting on a trailer and going home)... and regularly wipe the exposed areas with 'petroleum jelly' (Vaseline?)

Glad you found your tongue, and that it was not "the cat" as that would have been very painful and possibly give you some nasty disease...

you should count yourself lucky that my cat is outside and did not read that.
I know what you mean regarding water"proof". Some things actually ARE waterproof though. for instance, the bottles of soda. It is difficult for me to understand why waterproof to this standard, in a connexion, should be so infinitely hard to produce. And, if titanic had had enough empty soda bottles onboard, it never would have sunk!

Anyhow, how would you make sure, in your connexion suggestion, that the battery poles did not meet each other?

(bert, what is EMK?)

[CDK]

Originally Posted by BertKu

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

I cannot believe that this is the product you need. It is a silicone or similar grease filled with silver flakes, used to obtain both low friction and conductance between mobile objects, like the top end of a wave guide in a radar transmitter.
But I read that you ordered a sample, so you can soon determine its usefulness yourself; I fear the resistance will be disappointing.

[masalai]

The oil filled cylinders to exclude water (corrosion) and for thermal dissipation is nice, but the stuff used in power-line transformers for that purpose, is VERY toxic and a thermal runaway explosion could cause more problems than any other option... Not on the list as far as I am concerned...

[sigurd]

bad idea then... no other suitable fluid? But those little dehumidifier pellet bags, they put them with computers and such when shipping; that would be a good idea..

[capt vimes]

Originally Posted by CDK

I cannot believe that this is the product you need. It is a silicone or similar grease filled with silver flakes, used to obtain both low friction and conductance between mobile objects, like the top end of a wave guide in a radar transmitter.
But I read that you ordered a sample, so you can soon determine its usefulness yourself; I fear the resistance will be disappointing.

the restinstances of such conductive greases or adhesives are in the range of less than 10^-3 ohm per cm....
http://pdf.directindustry.com/pdf/ma...407-13428.html

[CDK]

Originally Posted by capt vimes

the restinstances of such conductive greases or adhesives are in the range of less than 10^-3 ohm per cm....
http://pdf.directindustry.com/pdf/ma...407-13428.html

Please tell me where grease is mentioned on that page!

[portacruise]

I must be missing something, here. Even if the grease IS conducting, what's to prevent it from causing a short circuit between cells. All grease I know of does not stay in the exact spot it is placed. You wind up with a big mess due to vibration, gravity, etc. Removing a cell to replace with be a slippery endeavor at the very least, as well.

Porta

Originally Posted by CDK

I cannot believe that this is the product you need. It is a silicone or similar grease filled with silver flakes, used to obtain both low friction and conductance between mobile objects, like the top end of a wave guide in a radar transmitter.
But I read that you ordered a sample, so you can soon determine its usefulness yourself; I fear the resistance will be disappointing.

[capt vimes]

Originally Posted by CDK

Please tell me where grease is mentioned on that page!

happy with that:
http://www.2spi.com/catalog/vac/silv...-techdata.html

this was the only exmaple i found in a hurry... having < 0.01 ohm per cm...

[Submarine Tom]

Originally Posted by sigurd

bad idea then... no other suitable fluid? But those little dehumidifier pellet bags, they put them with computers and such when shipping; that would be a good idea..

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

[sigurd]

Masalai, by the time you are going to launch the boat, you can probably buy much better genset than the noisy IC you talked about. What about a Cyclone engine for instance? burns anything, and is more silent and compact, probably. They are not in mass production yet, far as I know, but will probably be by that time?
I've a soft spot for thermoacoustic devices - should be even more cheap, compact, quieter and burn anything. I know, off topic, ssshhh.