Batteries and New Battery Technologies

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

 

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

 

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.

 

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...

 

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.

 

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?)

 

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 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...

 

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..

 

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/m...ctive-product-selector-guide/17407-13428.html

 

Please tell me where grease is mentioned on that page!

 

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

 

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

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

 

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

 

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.